pyspark.rdd — PySpark 3.5.5 documentation (original) (raw)
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import copy import sys import os import operator import shlex import warnings import heapq import bisect import random from subprocess import Popen, PIPE from threading import Thread from collections import defaultdict from itertools import chain from functools import reduce from math import sqrt, log, isinf, isnan, pow, ceil from typing import ( Any, Callable, Dict, Generic, Hashable, Iterable, Iterator, IO, List, NoReturn, Optional, Sequence, Tuple, Union, TypeVar, cast, overload, TYPE_CHECKING, )
from pyspark.java_gateway import local_connect_and_auth from pyspark.serializers import ( AutoBatchedSerializer, BatchedSerializer, NoOpSerializer, CartesianDeserializer, CloudPickleSerializer, PairDeserializer, CPickleSerializer, Serializer, pack_long, read_int, write_int, ) from pyspark.join import ( python_join, python_left_outer_join, python_right_outer_join, python_full_outer_join, python_cogroup, ) from pyspark.statcounter import StatCounter from pyspark.rddsampler import RDDSampler, RDDRangeSampler, RDDStratifiedSampler from pyspark.storagelevel import StorageLevel from pyspark.resource.requests import ExecutorResourceRequests, TaskResourceRequests from pyspark.resource.profile import ResourceProfile from pyspark.resultiterable import ResultIterable from pyspark.shuffle import ( Aggregator, ExternalMerger, get_used_memory, ExternalSorter, ExternalGroupBy, ) from pyspark.traceback_utils import SCCallSiteSync from pyspark.util import fail_on_stopiteration, _parse_memory from pyspark.errors import PySparkRuntimeError
if TYPE_CHECKING: import socket import io
from pyspark._typing import NonUDFType
from pyspark._typing import S, NumberOrArray
from pyspark.context import SparkContext
from pyspark.sql.pandas._typing import (
PandasScalarUDFType,
PandasGroupedMapUDFType,
PandasGroupedAggUDFType,
PandasWindowAggUDFType,
PandasScalarIterUDFType,
PandasMapIterUDFType,
PandasCogroupedMapUDFType,
ArrowMapIterUDFType,
PandasGroupedMapUDFWithStateType,
)
from pyspark.sql.dataframe import DataFrame
from pyspark.sql.types import AtomicType, StructType
from pyspark.sql._typing import (
AtomicValue,
RowLike,
SQLArrowBatchedUDFType,
SQLArrowTableUDFType,
SQLBatchedUDFType,
SQLTableUDFType,
)
from py4j.java_gateway import JavaObject
from py4j.java_collections import JavaArrayT = TypeVar("T") T_co = TypeVar("T_co", covariant=True) U = TypeVar("U") K = TypeVar("K", bound=Hashable) V = TypeVar("V") V1 = TypeVar("V1") V2 = TypeVar("V2") V3 = TypeVar("V3")
all = ["RDD"]
class PythonEvalType: """ Evaluation type of python rdd.
These values are internal to PySpark.
These values should match values in org.apache.spark.api.python.PythonEvalType.
"""
NON_UDF: "NonUDFType" = 0
SQL_BATCHED_UDF: "SQLBatchedUDFType" = 100
SQL_ARROW_BATCHED_UDF: "SQLArrowBatchedUDFType" = 101
SQL_SCALAR_PANDAS_UDF: "PandasScalarUDFType" = 200
SQL_GROUPED_MAP_PANDAS_UDF: "PandasGroupedMapUDFType" = 201
SQL_GROUPED_AGG_PANDAS_UDF: "PandasGroupedAggUDFType" = 202
SQL_WINDOW_AGG_PANDAS_UDF: "PandasWindowAggUDFType" = 203
SQL_SCALAR_PANDAS_ITER_UDF: "PandasScalarIterUDFType" = 204
SQL_MAP_PANDAS_ITER_UDF: "PandasMapIterUDFType" = 205
SQL_COGROUPED_MAP_PANDAS_UDF: "PandasCogroupedMapUDFType" = 206
SQL_MAP_ARROW_ITER_UDF: "ArrowMapIterUDFType" = 207
SQL_GROUPED_MAP_PANDAS_UDF_WITH_STATE: "PandasGroupedMapUDFWithStateType" = 208
SQL_TABLE_UDF: "SQLTableUDFType" = 300
SQL_ARROW_TABLE_UDF: "SQLArrowTableUDFType" = 301def portable_hash(x: Hashable) -> int: """ This function returns consistent hash code for builtin types, especially for None and tuple with None.
The algorithm is similar to that one used by CPython 2.7
Examples
--------
>>> portable_hash(None)
0
>>> portable_hash((None, 1)) & 0xffffffff
219750521
"""
if "PYTHONHASHSEED" not in os.environ:
raise PySparkRuntimeError(
error_class="PYTHON_HASH_SEED_NOT_SET",
message_parameters={},
)
if x is None:
return 0
if isinstance(x, tuple):
h = 0x345678
for i in x:
h ^= portable_hash(i)
h *= 1000003
h &= sys.maxsize
h ^= len(x)
if h == -1:
h = -2
return int(h)
return hash(x)class BoundedFloat(float): """ Bounded value is generated by approximate job, with confidence and low bound and high bound.
Examples
--------
>>> BoundedFloat(100.0, 0.95, 95.0, 105.0)
100.0
"""
confidence: float
low: float
high: float
def __new__(cls, mean: float, confidence: float, low: float, high: float) -> "BoundedFloat":
obj = float.__new__(cls, mean)
obj.confidence = confidence
obj.low = low
obj.high = high
return objdef _create_local_socket(sock_info: "JavaArray") -> "io.BufferedRWPair": """ Create a local socket that can be used to load deserialized data from the JVM
Parameters
----------
sock_info : tuple
Tuple containing port number and authentication secret for a local socket.
Returns
-------
sockfile file descriptor of the local socket
"""
sockfile: "io.BufferedRWPair"
sock: "socket.socket"
port: int = sock_info[0]
auth_secret: str = sock_info[1]
sockfile, sock = local_connect_and_auth(port, auth_secret)
# The RDD materialization time is unpredictable, if we set a timeout for socket reading
# operation, it will very possibly fail. See SPARK-18281.
sock.settimeout(None)
return sockfiledef _load_from_socket(sock_info: "JavaArray", serializer: Serializer) -> Iterator[Any]: """ Connect to a local socket described by sock_info and use the given serializer to yield data
Parameters
----------
sock_info : tuple
Tuple containing port number and authentication secret for a local socket.
serializer : class:`Serializer`
The PySpark serializer to use
Returns
-------
result of meth:`Serializer.load_stream`,
usually a generator that yields deserialized data
"""
sockfile = _create_local_socket(sock_info)
# The socket will be automatically closed when garbage-collected.
return serializer.load_stream(sockfile)def _local_iterator_from_socket(sock_info: "JavaArray", serializer: Serializer) -> Iterator[Any]: class PyLocalIterable: """Create a synchronous local iterable over a socket"""
def __init__(self, _sock_info: "JavaArray", _serializer: Serializer):
port: int
auth_secret: str
jsocket_auth_server: "JavaObject"
port, auth_secret, self.jsocket_auth_server = _sock_info
self._sockfile = _create_local_socket((port, auth_secret))
self._serializer = _serializer
self._read_iter: Iterator[Any] = iter([]) # Initialize as empty iterator
self._read_status = 1
def __iter__(self) -> Iterator[Any]:
while self._read_status == 1:
# Request next partition data from Java
write_int(1, self._sockfile)
self._sockfile.flush()
# If response is 1 then there is a partition to read, if 0 then fully consumed
self._read_status = read_int(self._sockfile)
if self._read_status == 1:
# Load the partition data as a stream and read each item
self._read_iter = self._serializer.load_stream(self._sockfile)
for item in self._read_iter:
yield item
# An error occurred, join serving thread and raise any exceptions from the JVM
elif self._read_status == -1:
self.jsocket_auth_server.getResult()
def __del__(self) -> None:
# If local iterator is not fully consumed,
if self._read_status == 1:
try:
# Finish consuming partition data stream
for _ in self._read_iter:
pass
# Tell Java to stop sending data and close connection
write_int(0, self._sockfile)
self._sockfile.flush()
except Exception:
# Ignore any errors, socket is automatically closed when garbage-collected
pass
return iter(PyLocalIterable(sock_info, serializer))class Partitioner: def init(self, numPartitions: int, partitionFunc: Callable[[Any], int]): self.numPartitions = numPartitions self.partitionFunc = partitionFunc
def __eq__(self, other: Any) -> bool:
return (
isinstance(other, Partitioner)
and self.numPartitions == other.numPartitions
and self.partitionFunc == other.partitionFunc
)
def __call__(self, k: Any) -> int:
return self.partitionFunc(k) % self.numPartitions[docs]class RDD(Generic[T_co]):
"""
A Resilient Distributed Dataset (RDD), the basic abstraction in Spark.
Represents an immutable, partitioned collection of elements that can be
operated on in parallel.
"""
def __init__(
self,
jrdd: "JavaObject",
ctx: "SparkContext",
jrdd_deserializer: Serializer = AutoBatchedSerializer(CPickleSerializer()),
):
self._jrdd = jrdd
self.is_cached = False
self.is_checkpointed = False
self.has_resource_profile = False
self.ctx = ctx
self._jrdd_deserializer = jrdd_deserializer
self._id = jrdd.id()
self.partitioner: Optional[Partitioner] = None
def _pickled(self: "RDD[T]") -> "RDD[T]":
return self._reserialize(AutoBatchedSerializer(CPickleSerializer()))[docs] def id(self) -> int: """ A unique ID for this RDD (within its SparkContext).
.. versionadded:: 0.7.0
Returns
-------
int
The unique ID for this :class:`RDD`
Examples
--------
>>> rdd = sc.range(5)
>>> rdd.id() # doctest: +SKIP
3
"""
return self._id
def __repr__(self) -> str:
return self._jrdd.toString()
def __getnewargs__(self) -> NoReturn:
# This method is called when attempting to pickle an RDD, which is always an error:
raise PySparkRuntimeError(
error_class="RDD_TRANSFORM_ONLY_VALID_ON_DRIVER",
message_parameters={},
)
@property
def context(self) -> "SparkContext":
"""
The :class:`SparkContext` that this RDD was created on.
.. versionadded:: 0.7.0
Returns
-------
:class:`SparkContext`
The :class:`SparkContext` that this RDD was created on
Examples
--------
>>> rdd = sc.range(5)
>>> rdd.context
<SparkContext ...>
>>> rdd.context is sc
True
"""
return self.ctx[docs] def cache(self: "RDD[T]") -> "RDD[T]":
"""
Persist this RDD with the default storage level (MEMORY_ONLY).
.. versionadded:: 0.7.0
Returns
-------
:class:`RDD`
The same :class:`RDD` with storage level set to `MEMORY_ONLY`
See Also
--------
:meth:`RDD.persist`
:meth:`RDD.unpersist`
:meth:`RDD.getStorageLevel`
Examples
--------
>>> rdd = sc.range(5)
>>> rdd2 = rdd.cache()
>>> rdd2 is rdd
True
>>> str(rdd.getStorageLevel())
'Memory Serialized 1x Replicated'
>>> _ = rdd.unpersist()
"""
self.is_cached = True
self.persist(StorageLevel.MEMORY_ONLY)
return self[docs] def persist(self: "RDD[T]", storageLevel: StorageLevel = StorageLevel.MEMORY_ONLY) -> "RDD[T]":
"""
Set this RDD's storage level to persist its values across operations
after the first time it is computed. This can only be used to assign
a new storage level if the RDD does not have a storage level set yet.
If no storage level is specified defaults to (MEMORY_ONLY).
.. versionadded:: 0.9.1
Parameters
----------
storageLevel : :class:`StorageLevel`, default `MEMORY_ONLY`
the target storage level
Returns
-------
:class:`RDD`
The same :class:`RDD` with storage level set to `storageLevel`.
See Also
--------
:meth:`RDD.cache`
:meth:`RDD.unpersist`
:meth:`RDD.getStorageLevel`
Examples
--------
>>> rdd = sc.parallelize(["b", "a", "c"])
>>> rdd.persist().is_cached
True
>>> str(rdd.getStorageLevel())
'Memory Serialized 1x Replicated'
>>> _ = rdd.unpersist()
>>> rdd.is_cached
False
>>> from pyspark import StorageLevel
>>> rdd2 = sc.range(5)
>>> _ = rdd2.persist(StorageLevel.MEMORY_AND_DISK)
>>> rdd2.is_cached
True
>>> str(rdd2.getStorageLevel())
'Disk Memory Serialized 1x Replicated'
Can not override existing storage level
>>> _ = rdd2.persist(StorageLevel.MEMORY_ONLY_2)
Traceback (most recent call last):
...
py4j.protocol.Py4JJavaError: ...
Assign another storage level after `unpersist`
>>> _ = rdd2.unpersist()
>>> rdd2.is_cached
False
>>> _ = rdd2.persist(StorageLevel.MEMORY_ONLY_2)
>>> str(rdd2.getStorageLevel())
'Memory Serialized 2x Replicated'
>>> rdd2.is_cached
True
>>> _ = rdd2.unpersist()
"""
self.is_cached = True
javaStorageLevel = self.ctx._getJavaStorageLevel(storageLevel)
self._jrdd.persist(javaStorageLevel)
return self[docs] def unpersist(self: "RDD[T]", blocking: bool = False) -> "RDD[T]": """ Mark the RDD as non-persistent, and remove all blocks for it from memory and disk.
.. versionadded:: 0.9.1
Parameters
----------
blocking : bool, optional, default False
whether to block until all blocks are deleted
.. versionadded:: 3.0.0
Returns
-------
:class:`RDD`
The same :class:`RDD`
See Also
--------
:meth:`RDD.cache`
:meth:`RDD.persist`
:meth:`RDD.getStorageLevel`
Examples
--------
>>> rdd = sc.range(5)
>>> rdd.is_cached
False
>>> _ = rdd.unpersist()
>>> rdd.is_cached
False
>>> _ = rdd.cache()
>>> rdd.is_cached
True
>>> _ = rdd.unpersist()
>>> rdd.is_cached
False
>>> _ = rdd.unpersist()
"""
self.is_cached = False
self._jrdd.unpersist(blocking)
return self[docs] def checkpoint(self) -> None:
"""
Mark this RDD for checkpointing. It will be saved to a file inside the
checkpoint directory set with :meth:SparkContext.setCheckpointDir and
all references to its parent RDDs will be removed. This function must
be called before any job has been executed on this RDD. It is strongly
recommended that this RDD is persisted in memory, otherwise saving it
on a file will require recomputation.
.. versionadded:: 0.7.0
See Also
--------
:meth:`RDD.isCheckpointed`
:meth:`RDD.getCheckpointFile`
:meth:`RDD.localCheckpoint`
:meth:`SparkContext.setCheckpointDir`
:meth:`SparkContext.getCheckpointDir`
Examples
--------
>>> rdd = sc.range(5)
>>> rdd.is_checkpointed
False
>>> rdd.getCheckpointFile() == None
True
>>> rdd.checkpoint()
>>> rdd.is_checkpointed
True
>>> rdd.getCheckpointFile() == None
True
>>> rdd.count()
5
>>> rdd.is_checkpointed
True
>>> rdd.getCheckpointFile() == None
False
"""
self.is_checkpointed = True
self._jrdd.rdd().checkpoint()[docs] def isCheckpointed(self) -> bool: """ Return whether this RDD is checkpointed and materialized, either reliably or locally.
.. versionadded:: 0.7.0
Returns
-------
bool
whether this :class:`RDD` is checkpointed and materialized, either reliably or locally
See Also
--------
:meth:`RDD.checkpoint`
:meth:`RDD.getCheckpointFile`
:meth:`SparkContext.setCheckpointDir`
:meth:`SparkContext.getCheckpointDir`
"""
return self._jrdd.rdd().isCheckpointed()[docs] def localCheckpoint(self) -> None: """ Mark this RDD for local checkpointing using Spark's existing caching layer.
This method is for users who wish to truncate RDD lineages while skipping the expensive
step of replicating the materialized data in a reliable distributed file system. This is
useful for RDDs with long lineages that need to be truncated periodically (e.g. GraphX).
Local checkpointing sacrifices fault-tolerance for performance. In particular, checkpointed
data is written to ephemeral local storage in the executors instead of to a reliable,
fault-tolerant storage. The effect is that if an executor fails during the computation,
the checkpointed data may no longer be accessible, causing an irrecoverable job failure.
This is NOT safe to use with dynamic allocation, which removes executors along
with their cached blocks. If you must use both features, you are advised to set
`spark.dynamicAllocation.cachedExecutorIdleTimeout` to a high value.
The checkpoint directory set through :meth:`SparkContext.setCheckpointDir` is not used.
.. versionadded:: 2.2.0
See Also
--------
:meth:`RDD.checkpoint`
:meth:`RDD.isLocallyCheckpointed`
Examples
--------
>>> rdd = sc.range(5)
>>> rdd.isLocallyCheckpointed()
False
>>> rdd.localCheckpoint()
>>> rdd.isLocallyCheckpointed()
True
"""
self._jrdd.rdd().localCheckpoint()[docs] def isLocallyCheckpointed(self) -> bool: """ Return whether this RDD is marked for local checkpointing.
Exposed for testing.
.. versionadded:: 2.2.0
Returns
-------
bool
whether this :class:`RDD` is marked for local checkpointing
See Also
--------
:meth:`RDD.localCheckpoint`
"""
return self._jrdd.rdd().isLocallyCheckpointed()[docs] def getCheckpointFile(self) -> Optional[str]: """ Gets the name of the file to which this RDD was checkpointed
Not defined if RDD is checkpointed locally.
.. versionadded:: 0.7.0
Returns
-------
str
the name of the file to which this :class:`RDD` was checkpointed
See Also
--------
:meth:`RDD.checkpoint`
:meth:`SparkContext.setCheckpointDir`
:meth:`SparkContext.getCheckpointDir`
"""
checkpointFile = self._jrdd.rdd().getCheckpointFile()
return checkpointFile.get() if checkpointFile.isDefined() else None[docs] def cleanShuffleDependencies(self, blocking: bool = False) -> None: """ Removes an RDD's shuffles and it's non-persisted ancestors.
When running without a shuffle service, cleaning up shuffle files enables downscaling.
If you use the RDD after this call, you should checkpoint and materialize it first.
.. versionadded:: 3.3.0
Parameters
----------
blocking : bool, optional, default False
whether to block on shuffle cleanup tasks
Notes
-----
This API is a developer API.
"""
self._jrdd.rdd().cleanShuffleDependencies(blocking)[docs] def map(self: "RDD[T]", f: Callable[[T], U], preservesPartitioning: bool = False) -> "RDD[U]": """ Return a new RDD by applying a function to each element of this RDD.
.. versionadded:: 0.7.0
Parameters
----------
f : function
a function to run on each element of the RDD
preservesPartitioning : bool, optional, default False
indicates whether the input function preserves the partitioner,
which should be False unless this is a pair RDD and the input
Returns
-------
:class:`RDD`
a new :class:`RDD` by applying a function to all elements
See Also
--------
:meth:`RDD.flatMap`
:meth:`RDD.mapPartitions`
:meth:`RDD.mapPartitionsWithIndex`
:meth:`RDD.mapPartitionsWithSplit`
Examples
--------
>>> rdd = sc.parallelize(["b", "a", "c"])
>>> sorted(rdd.map(lambda x: (x, 1)).collect())
[('a', 1), ('b', 1), ('c', 1)]
"""
def func(_: int, iterator: Iterable[T]) -> Iterable[U]:
return map(fail_on_stopiteration(f), iterator)
return self.mapPartitionsWithIndex(func, preservesPartitioning)[docs] def flatMap( self: "RDD[T]", f: Callable[[T], Iterable[U]], preservesPartitioning: bool = False ) -> "RDD[U]": """ Return a new RDD by first applying a function to all elements of this RDD, and then flattening the results.
.. versionadded:: 0.7.0
Parameters
----------
f : function
a function to turn a T into a sequence of U
preservesPartitioning : bool, optional, default False
indicates whether the input function preserves the partitioner,
which should be False unless this is a pair RDD and the input
Returns
-------
:class:`RDD`
a new :class:`RDD` by applying a function to all elements
See Also
--------
:meth:`RDD.map`
:meth:`RDD.mapPartitions`
:meth:`RDD.mapPartitionsWithIndex`
:meth:`RDD.mapPartitionsWithSplit`
Examples
--------
>>> rdd = sc.parallelize([2, 3, 4])
>>> sorted(rdd.flatMap(lambda x: range(1, x)).collect())
[1, 1, 1, 2, 2, 3]
>>> sorted(rdd.flatMap(lambda x: [(x, x), (x, x)]).collect())
[(2, 2), (2, 2), (3, 3), (3, 3), (4, 4), (4, 4)]
"""
def func(_: int, iterator: Iterable[T]) -> Iterable[U]:
return chain.from_iterable(map(fail_on_stopiteration(f), iterator))
return self.mapPartitionsWithIndex(func, preservesPartitioning)[docs] def mapPartitions( self: "RDD[T]", f: Callable[[Iterable[T]], Iterable[U]], preservesPartitioning: bool = False ) -> "RDD[U]": """ Return a new RDD by applying a function to each partition of this RDD.
.. versionadded:: 0.7.0
Parameters
----------
f : function
a function to run on each partition of the RDD
preservesPartitioning : bool, optional, default False
indicates whether the input function preserves the partitioner,
which should be False unless this is a pair RDD and the input
Returns
-------
:class:`RDD`
a new :class:`RDD` by applying a function to each partition
See Also
--------
:meth:`RDD.map`
:meth:`RDD.flatMap`
:meth:`RDD.mapPartitionsWithIndex`
:meth:`RDD.mapPartitionsWithSplit`
:meth:`RDDBarrier.mapPartitions`
Examples
--------
>>> rdd = sc.parallelize([1, 2, 3, 4], 2)
>>> def f(iterator): yield sum(iterator)
...
>>> rdd.mapPartitions(f).collect()
[3, 7]
"""
def func(_: int, iterator: Iterable[T]) -> Iterable[U]:
return f(iterator)
return self.mapPartitionsWithIndex(func, preservesPartitioning)[docs] def mapPartitionsWithIndex( self: "RDD[T]", f: Callable[[int, Iterable[T]], Iterable[U]], preservesPartitioning: bool = False, ) -> "RDD[U]": """ Return a new RDD by applying a function to each partition of this RDD, while tracking the index of the original partition.
.. versionadded:: 0.7.0
Parameters
----------
f : function
a function to run on each partition of the RDD
preservesPartitioning : bool, optional, default False
indicates whether the input function preserves the partitioner,
which should be False unless this is a pair RDD and the input
Returns
-------
:class:`RDD`
a new :class:`RDD` by applying a function to each partition
See Also
--------
:meth:`RDD.map`
:meth:`RDD.flatMap`
:meth:`RDD.mapPartitions`
:meth:`RDD.mapPartitionsWithSplit`
:meth:`RDDBarrier.mapPartitionsWithIndex`
Examples
--------
>>> rdd = sc.parallelize([1, 2, 3, 4], 4)
>>> def f(splitIndex, iterator): yield splitIndex
...
>>> rdd.mapPartitionsWithIndex(f).sum()
6
"""
return PipelinedRDD(self, f, preservesPartitioning)[docs] def mapPartitionsWithSplit( self: "RDD[T]", f: Callable[[int, Iterable[T]], Iterable[U]], preservesPartitioning: bool = False, ) -> "RDD[U]": """ Return a new RDD by applying a function to each partition of this RDD, while tracking the index of the original partition.
.. versionadded:: 0.7.0
.. deprecated:: 0.9.0
use meth:`RDD.mapPartitionsWithIndex` instead.
Parameters
----------
f : function
a function to run on each partition of the RDD
preservesPartitioning : bool, optional, default False
indicates whether the input function preserves the partitioner,
which should be False unless this is a pair RDD and the input
Returns
-------
:class:`RDD`
a new :class:`RDD` by applying a function to each partition
See Also
--------
:meth:`RDD.map`
:meth:`RDD.flatMap`
:meth:`RDD.mapPartitions`
:meth:`RDD.mapPartitionsWithIndex`
Examples
--------
>>> rdd = sc.parallelize([1, 2, 3, 4], 4)
>>> def f(splitIndex, iterator): yield splitIndex
...
>>> rdd.mapPartitionsWithSplit(f).sum()
6
"""
warnings.warn(
"mapPartitionsWithSplit is deprecated; use mapPartitionsWithIndex instead",
FutureWarning,
stacklevel=2,
)
return self.mapPartitionsWithIndex(f, preservesPartitioning)[docs] def getNumPartitions(self) -> int: """ Returns the number of partitions in RDD
.. versionadded:: 1.1.0
Returns
-------
int
number of partitions
Examples
--------
>>> rdd = sc.parallelize([1, 2, 3, 4], 2)
>>> rdd.getNumPartitions()
2
"""
return self._jrdd.partitions().size()[docs] def filter(self: "RDD[T]", f: Callable[[T], bool]) -> "RDD[T]": """ Return a new RDD containing only the elements that satisfy a predicate.
.. versionadded:: 0.7.0
Parameters
----------
f : function
a function to run on each element of the RDD
Returns
-------
:class:`RDD`
a new :class:`RDD` by applying a function to each element
See Also
--------
:meth:`RDD.map`
Examples
--------
>>> rdd = sc.parallelize([1, 2, 3, 4, 5])
>>> rdd.filter(lambda x: x % 2 == 0).collect()
[2, 4]
"""
def func(iterator: Iterable[T]) -> Iterable[T]:
return filter(fail_on_stopiteration(f), iterator)
return self.mapPartitions(func, True)[docs] def distinct(self: "RDD[T]", numPartitions: Optional[int] = None) -> "RDD[T]": """ Return a new RDD containing the distinct elements in this RDD.
.. versionadded:: 0.7.0
Parameters
----------
numPartitions : int, optional
the number of partitions in new :class:`RDD`
Returns
-------
:class:`RDD`
a new :class:`RDD` containing the distinct elements
See Also
--------
:meth:`RDD.countApproxDistinct`
Examples
--------
>>> sorted(sc.parallelize([1, 1, 2, 3]).distinct().collect())
[1, 2, 3]
"""
return (
self.map(lambda x: (x, None))
.reduceByKey(lambda x, _: x, numPartitions)
.map(lambda x: x[0])
)[docs] def sample( self: "RDD[T]", withReplacement: bool, fraction: float, seed: Optional[int] = None ) -> "RDD[T]": """ Return a sampled subset of this RDD.
.. versionadded:: 0.7.0
Parameters
----------
withReplacement : bool
can elements be sampled multiple times (replaced when sampled out)
fraction : float
expected size of the sample as a fraction of this RDD's size
without replacement: probability that each element is chosen; fraction must be [0, 1]
with replacement: expected number of times each element is chosen; fraction must be >= 0
seed : int, optional
seed for the random number generator
Returns
-------
:class:`RDD`
a new :class:`RDD` containing a sampled subset of elements
See Also
--------
:meth:`RDD.takeSample`
:meth:`RDD.sampleByKey`
:meth:`pyspark.sql.DataFrame.sample`
Notes
-----
This is not guaranteed to provide exactly the fraction specified of the total
count of the given :class:`DataFrame`.
Examples
--------
>>> rdd = sc.parallelize(range(100), 4)
>>> 6 <= rdd.sample(False, 0.1, 81).count() <= 14
True
"""
if not fraction >= 0:
raise ValueError("Fraction must be nonnegative.")
return self.mapPartitionsWithIndex(RDDSampler(withReplacement, fraction, seed).func, True)[docs] def randomSplit( self: "RDD[T]", weights: Sequence[Union[int, float]], seed: Optional[int] = None ) -> "List[RDD[T]]": """ Randomly splits this RDD with the provided weights.
.. versionadded:: 1.3.0
Parameters
----------
weights : list
weights for splits, will be normalized if they don't sum to 1
seed : int, optional
random seed
Returns
-------
list
split :class:`RDD`\\s in a list
See Also
--------
:meth:`pyspark.sql.DataFrame.randomSplit`
Examples
--------
>>> rdd = sc.parallelize(range(500), 1)
>>> rdd1, rdd2 = rdd.randomSplit([2, 3], 17)
>>> len(rdd1.collect() + rdd2.collect())
500
>>> 150 < rdd1.count() < 250
True
>>> 250 < rdd2.count() < 350
True
"""
if not all(w >= 0 for w in weights):
raise ValueError("Weights must be nonnegative")
s = float(sum(weights))
if not s > 0:
raise ValueError("Sum of weights must be positive")
cweights = [0.0]
for w in weights:
cweights.append(cweights[-1] + w / s)
if seed is None:
seed = random.randint(0, 2**32 - 1)
return [
self.mapPartitionsWithIndex(RDDRangeSampler(lb, ub, seed).func, True)
for lb, ub in zip(cweights, cweights[1:])
]
# this is ported from scala/spark/RDD.scala[docs] def takeSample( self: "RDD[T]", withReplacement: bool, num: int, seed: Optional[int] = None ) -> List[T]: """ Return a fixed-size sampled subset of this RDD.
.. versionadded:: 1.3.0
Parameters
----------
withReplacement : bool
whether sampling is done with replacement
num : int
size of the returned sample
seed : int, optional
random seed
Returns
-------
list
a fixed-size sampled subset of this :class:`RDD` in an array
See Also
--------
:meth:`RDD.sample`
Notes
-----
This method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
Examples
--------
>>> import sys
>>> rdd = sc.parallelize(range(0, 10))
>>> len(rdd.takeSample(True, 20, 1))
20
>>> len(rdd.takeSample(False, 5, 2))
5
>>> len(rdd.takeSample(False, 15, 3))
10
>>> sc.range(0, 10).takeSample(False, sys.maxsize)
Traceback (most recent call last):
...
ValueError: Sample size cannot be greater than ...
"""
numStDev = 10.0
maxSampleSize = sys.maxsize - int(numStDev * sqrt(sys.maxsize))
if num < 0:
raise ValueError("Sample size cannot be negative.")
elif num > maxSampleSize:
raise ValueError("Sample size cannot be greater than %d." % maxSampleSize)
if num == 0 or self.getNumPartitions() == 0:
return []
initialCount = self.count()
if initialCount == 0:
return []
rand = random.Random(seed)
if (not withReplacement) and num >= initialCount:
# shuffle current RDD and return
samples = self.collect()
rand.shuffle(samples)
return samples
fraction = RDD._computeFractionForSampleSize(num, initialCount, withReplacement)
samples = self.sample(withReplacement, fraction, seed).collect()
# If the first sample didn't turn out large enough, keep trying to take samples;
# this shouldn't happen often because we use a big multiplier for their initial size.
# See: scala/spark/RDD.scala
while len(samples) < num:
# TODO: add log warning for when more than one iteration was run
seed = rand.randint(0, sys.maxsize)
samples = self.sample(withReplacement, fraction, seed).collect()
rand.shuffle(samples)
return samples[0:num]
@staticmethod
def _computeFractionForSampleSize(
sampleSizeLowerBound: int, total: int, withReplacement: bool
) -> float:
"""
Returns a sampling rate that guarantees a sample of
size >= sampleSizeLowerBound 99.99% of the time.
How the sampling rate is determined:
Let p = num / total, where num is the sample size and total is the
total number of data points in the RDD. We're trying to compute
q > p such that
- when sampling with replacement, we're drawing each data point
with prob_i ~ Pois(q), where we want to guarantee
Pr[s < num] < 0.0001 for s = sum(prob_i for i from 0 to
total), i.e. the failure rate of not having a sufficiently large
sample < 0.0001. Setting q = p + 5 * sqrt(p/total) is sufficient
to guarantee 0.9999 success rate for num > 12, but we need a
slightly larger q (9 empirically determined).
- when sampling without replacement, we're drawing each data point
with prob_i ~ Binomial(total, fraction) and our choice of q
guarantees 1-delta, or 0.9999 success rate, where success rate is
defined the same as in sampling with replacement.
"""
fraction = float(sampleSizeLowerBound) / total
if withReplacement:
numStDev = 5
if sampleSizeLowerBound < 12:
numStDev = 9
return fraction + numStDev * sqrt(fraction / total)
else:
delta = 0.00005
gamma = -log(delta) / total
return min(1, fraction + gamma + sqrt(gamma * gamma + 2 * gamma * fraction))[docs] def union(self: "RDD[T]", other: "RDD[U]") -> "RDD[Union[T, U]]": """ Return the union of this RDD and another one.
.. versionadded:: 0.7.0
Parameters
----------
other : :class:`RDD`
another :class:`RDD`
Returns
-------
:class:`RDD`
the union of this :class:`RDD` and another one
See Also
--------
:meth:`SparkContext.union`
:meth:`pyspark.sql.DataFrame.union`
Examples
--------
>>> rdd = sc.parallelize([1, 1, 2, 3])
>>> rdd.union(rdd).collect()
[1, 1, 2, 3, 1, 1, 2, 3]
"""
if self._jrdd_deserializer == other._jrdd_deserializer:
rdd: "RDD[Union[T, U]]" = RDD(
self._jrdd.union(other._jrdd), self.ctx, self._jrdd_deserializer
)
else:
# These RDDs contain data in different serialized formats, so we
# must normalize them to the default serializer.
self_copy = self._reserialize()
other_copy = other._reserialize()
rdd = RDD(self_copy._jrdd.union(other_copy._jrdd), self.ctx, self.ctx.serializer)
if (
self.partitioner == other.partitioner
and self.getNumPartitions() == rdd.getNumPartitions()
):
rdd.partitioner = self.partitioner
return rdd[docs] def intersection(self: "RDD[T]", other: "RDD[T]") -> "RDD[T]": """ Return the intersection of this RDD and another one. The output will not contain any duplicate elements, even if the input RDDs did.
.. versionadded:: 1.0.0
Parameters
----------
other : :class:`RDD`
another :class:`RDD`
Returns
-------
:class:`RDD`
the intersection of this :class:`RDD` and another one
See Also
--------
:meth:`pyspark.sql.DataFrame.intersect`
Notes
-----
This method performs a shuffle internally.
Examples
--------
>>> rdd1 = sc.parallelize([1, 10, 2, 3, 4, 5])
>>> rdd2 = sc.parallelize([1, 6, 2, 3, 7, 8])
>>> rdd1.intersection(rdd2).collect()
[1, 2, 3]
"""
return (
self.map(lambda v: (v, None))
.cogroup(other.map(lambda v: (v, None)))
.filter(lambda k_vs: all(k_vs[1]))
.keys()
)
def _reserialize(self: "RDD[T]", serializer: Optional[Serializer] = None) -> "RDD[T]":
serializer = serializer or self.ctx.serializer
if self._jrdd_deserializer != serializer:
self = self.map(lambda x: x, preservesPartitioning=True)
self._jrdd_deserializer = serializer
return self
def __add__(self: "RDD[T]", other: "RDD[U]") -> "RDD[Union[T, U]]":
"""
Return the union of this RDD and another one.
Examples
--------
>>> rdd = sc.parallelize([1, 1, 2, 3])
>>> (rdd + rdd).collect()
[1, 1, 2, 3, 1, 1, 2, 3]
"""
if not isinstance(other, RDD):
raise TypeError
return self.union(other)
@overload
def repartitionAndSortWithinPartitions(
self: "RDD[Tuple[S, V]]",
numPartitions: Optional[int] = ...,
partitionFunc: Callable[["S"], int] = ...,
ascending: bool = ...,
) -> "RDD[Tuple[S, V]]":
...
@overload
def repartitionAndSortWithinPartitions(
self: "RDD[Tuple[K, V]]",
numPartitions: Optional[int],
partitionFunc: Callable[[K], int],
ascending: bool,
keyfunc: Callable[[K], "S"],
) -> "RDD[Tuple[K, V]]":
...
@overload
def repartitionAndSortWithinPartitions(
self: "RDD[Tuple[K, V]]",
numPartitions: Optional[int] = ...,
partitionFunc: Callable[[K], int] = ...,
ascending: bool = ...,
*,
keyfunc: Callable[[K], "S"],
) -> "RDD[Tuple[K, V]]":
...[docs] def repartitionAndSortWithinPartitions( self: "RDD[Tuple[Any, Any]]", numPartitions: Optional[int] = None, partitionFunc: Callable[[Any], int] = portable_hash, ascending: bool = True, keyfunc: Callable[[Any], Any] = lambda x: x, ) -> "RDD[Tuple[Any, Any]]": """ Repartition the RDD according to the given partitioner and, within each resulting partition, sort records by their keys.
.. versionadded:: 1.2.0
Parameters
----------
numPartitions : int, optional
the number of partitions in new :class:`RDD`
partitionFunc : function, optional, default `portable_hash`
a function to compute the partition index
ascending : bool, optional, default True
sort the keys in ascending or descending order
keyfunc : function, optional, default identity mapping
a function to compute the key
Returns
-------
:class:`RDD`
a new :class:`RDD`
See Also
--------
:meth:`RDD.repartition`
:meth:`RDD.partitionBy`
:meth:`RDD.sortBy`
:meth:`RDD.sortByKey`
Examples
--------
>>> rdd = sc.parallelize([(0, 5), (3, 8), (2, 6), (0, 8), (3, 8), (1, 3)])
>>> rdd2 = rdd.repartitionAndSortWithinPartitions(2, lambda x: x % 2, True)
>>> rdd2.glom().collect()
[[(0, 5), (0, 8), (2, 6)], [(1, 3), (3, 8), (3, 8)]]
"""
if numPartitions is None:
numPartitions = self._defaultReducePartitions()
memory = self._memory_limit()
serializer = self._jrdd_deserializer
def sortPartition(iterator: Iterable[Tuple[K, V]]) -> Iterable[Tuple[K, V]]:
sort = ExternalSorter(memory * 0.9, serializer).sorted
return iter(sort(iterator, key=lambda k_v: keyfunc(k_v[0]), reverse=(not ascending)))
return self.partitionBy(numPartitions, partitionFunc).mapPartitions(sortPartition, True)
@overload
def sortByKey(
self: "RDD[Tuple[S, V]]",
ascending: bool = ...,
numPartitions: Optional[int] = ...,
) -> "RDD[Tuple[K, V]]":
...
@overload
def sortByKey(
self: "RDD[Tuple[K, V]]",
ascending: bool,
numPartitions: int,
keyfunc: Callable[[K], "S"],
) -> "RDD[Tuple[K, V]]":
...
@overload
def sortByKey(
self: "RDD[Tuple[K, V]]",
ascending: bool = ...,
numPartitions: Optional[int] = ...,
*,
keyfunc: Callable[[K], "S"],
) -> "RDD[Tuple[K, V]]":
...[docs] def sortByKey( self: "RDD[Tuple[K, V]]", ascending: Optional[bool] = True, numPartitions: Optional[int] = None, keyfunc: Callable[[Any], Any] = lambda x: x, ) -> "RDD[Tuple[K, V]]": """ Sorts this RDD, which is assumed to consist of (key, value) pairs.
.. versionadded:: 0.9.1
Parameters
----------
ascending : bool, optional, default True
sort the keys in ascending or descending order
numPartitions : int, optional
the number of partitions in new :class:`RDD`
keyfunc : function, optional, default identity mapping
a function to compute the key
Returns
-------
:class:`RDD`
a new :class:`RDD`
See Also
--------
:meth:`RDD.sortBy`
:meth:`pyspark.sql.DataFrame.sort`
Examples
--------
>>> tmp = [('a', 1), ('b', 2), ('1', 3), ('d', 4), ('2', 5)]
>>> sc.parallelize(tmp).sortByKey().first()
('1', 3)
>>> sc.parallelize(tmp).sortByKey(True, 1).collect()
[('1', 3), ('2', 5), ('a', 1), ('b', 2), ('d', 4)]
>>> sc.parallelize(tmp).sortByKey(True, 2).collect()
[('1', 3), ('2', 5), ('a', 1), ('b', 2), ('d', 4)]
>>> tmp2 = [('Mary', 1), ('had', 2), ('a', 3), ('little', 4), ('lamb', 5)]
>>> tmp2.extend([('whose', 6), ('fleece', 7), ('was', 8), ('white', 9)])
>>> sc.parallelize(tmp2).sortByKey(True, 3, keyfunc=lambda k: k.lower()).collect()
[('a', 3), ('fleece', 7), ('had', 2), ('lamb', 5),...('white', 9), ('whose', 6)]
"""
if numPartitions is None:
numPartitions = self._defaultReducePartitions()
memory = self._memory_limit()
serializer = self._jrdd_deserializer
def sortPartition(iterator: Iterable[Tuple[K, V]]) -> Iterable[Tuple[K, V]]:
sort = ExternalSorter(memory * 0.9, serializer).sorted
return iter(sort(iterator, key=lambda kv: keyfunc(kv[0]), reverse=(not ascending)))
if numPartitions == 1:
if self.getNumPartitions() > 1:
self = self.coalesce(1)
return self.mapPartitions(sortPartition, True)
# first compute the boundary of each part via sampling: we want to partition
# the key-space into bins such that the bins have roughly the same
# number of (key, value) pairs falling into them
rddSize = self.count()
if not rddSize:
return self # empty RDD
maxSampleSize = numPartitions * 20.0 # constant from Spark's RangePartitioner
fraction = min(maxSampleSize / max(rddSize, 1), 1.0)
samples = self.sample(False, fraction, 1).map(lambda kv: kv[0]).collect()
samples = sorted(samples, key=keyfunc)
# we have numPartitions many parts but one of the them has
# an implicit boundary
bounds = [
samples[int(len(samples) * (i + 1) / numPartitions)]
for i in range(0, numPartitions - 1)
]
def rangePartitioner(k: K) -> int:
p = bisect.bisect_left(bounds, keyfunc(k))
if ascending:
return p
else:
return numPartitions - 1 - p # type: ignore[operator]
return self.partitionBy(numPartitions, rangePartitioner).mapPartitions(sortPartition, True)[docs] def sortBy( self: "RDD[T]", keyfunc: Callable[[T], "S"], ascending: bool = True, numPartitions: Optional[int] = None, ) -> "RDD[T]": """ Sorts this RDD by the given keyfunc
.. versionadded:: 1.1.0
Parameters
----------
keyfunc : function
a function to compute the key
ascending : bool, optional, default True
sort the keys in ascending or descending order
numPartitions : int, optional
the number of partitions in new :class:`RDD`
Returns
-------
:class:`RDD`
a new :class:`RDD`
See Also
--------
:meth:`RDD.sortByKey`
:meth:`pyspark.sql.DataFrame.sort`
Examples
--------
>>> tmp = [('a', 1), ('b', 2), ('1', 3), ('d', 4), ('2', 5)]
>>> sc.parallelize(tmp).sortBy(lambda x: x[0]).collect()
[('1', 3), ('2', 5), ('a', 1), ('b', 2), ('d', 4)]
>>> sc.parallelize(tmp).sortBy(lambda x: x[1]).collect()
[('a', 1), ('b', 2), ('1', 3), ('d', 4), ('2', 5)]
"""
return (
self.keyBy(keyfunc) # type: ignore[type-var]
.sortByKey(ascending, numPartitions)
.values()
)[docs] def glom(self: "RDD[T]") -> "RDD[List[T]]": """ Return an RDD created by coalescing all elements within each partition into a list.
.. versionadded:: 0.7.0
Returns
-------
:class:`RDD`
a new :class:`RDD` coalescing all elements within each partition into a list
Examples
--------
>>> rdd = sc.parallelize([1, 2, 3, 4], 2)
>>> sorted(rdd.glom().collect())
[[1, 2], [3, 4]]
"""
def func(iterator: Iterable[T]) -> Iterable[List[T]]:
yield list(iterator)
return self.mapPartitions(func)[docs] def cartesian(self: "RDD[T]", other: "RDD[U]") -> "RDD[Tuple[T, U]]":
"""
Return the Cartesian product of this RDD and another one, that is, the
RDD of all pairs of elements (a, b) where a is in self and
b is in other.
.. versionadded:: 0.7.0
Parameters
----------
other : :class:`RDD`
another :class:`RDD`
Returns
-------
:class:`RDD`
the Cartesian product of this :class:`RDD` and another one
See Also
--------
:meth:`pyspark.sql.DataFrame.crossJoin`
Examples
--------
>>> rdd = sc.parallelize([1, 2])
>>> sorted(rdd.cartesian(rdd).collect())
[(1, 1), (1, 2), (2, 1), (2, 2)]
"""
# Due to batching, we can't use the Java cartesian method.
deserializer = CartesianDeserializer(self._jrdd_deserializer, other._jrdd_deserializer)
return RDD(self._jrdd.cartesian(other._jrdd), self.ctx, deserializer)[docs] def groupBy( self: "RDD[T]", f: Callable[[T], K], numPartitions: Optional[int] = None, partitionFunc: Callable[[K], int] = portable_hash, ) -> "RDD[Tuple[K, Iterable[T]]]": """ Return an RDD of grouped items.
.. versionadded:: 0.7.0
Parameters
----------
f : function
a function to compute the key
numPartitions : int, optional
the number of partitions in new :class:`RDD`
partitionFunc : function, optional, default `portable_hash`
a function to compute the partition index
Returns
-------
:class:`RDD`
a new :class:`RDD` of grouped items
See Also
--------
:meth:`RDD.groupByKey`
:meth:`pyspark.sql.DataFrame.groupBy`
Examples
--------
>>> rdd = sc.parallelize([1, 1, 2, 3, 5, 8])
>>> result = rdd.groupBy(lambda x: x % 2).collect()
>>> sorted([(x, sorted(y)) for (x, y) in result])
[(0, [2, 8]), (1, [1, 1, 3, 5])]
"""
return self.map(lambda x: (f(x), x)).groupByKey(numPartitions, partitionFunc)[docs] def pipe( self, command: str, env: Optional[Dict[str, str]] = None, checkCode: bool = False ) -> "RDD[str]": """ Return an RDD created by piping elements to a forked external process.
.. versionadded:: 0.7.0
Parameters
----------
command : str
command to run.
env : dict, optional
environment variables to set.
checkCode : bool, optional
whether to check the return value of the shell command.
Returns
-------
:class:`RDD`
a new :class:`RDD` of strings
Examples
--------
>>> sc.parallelize(['1', '2', '', '3']).pipe('cat').collect()
['1', '2', '', '3']
"""
if env is None:
env = dict()
def func(iterator: Iterable[T]) -> Iterable[str]:
pipe = Popen(shlex.split(command), env=env, stdin=PIPE, stdout=PIPE)
def pipe_objs(out: IO[bytes]) -> None:
for obj in iterator:
s = str(obj).rstrip("\n") + "\n"
out.write(s.encode("utf-8"))
out.close()
Thread(target=pipe_objs, args=[pipe.stdin]).start()
def check_return_code() -> Iterable[int]:
pipe.wait()
if checkCode and pipe.returncode:
raise PySparkRuntimeError(
error_class="PIPE_FUNCTION_EXITED",
message_parameters={
"func_name": command,
"error_code": str(pipe.returncode),
},
)
else:
for i in range(0):
yield i
return (
cast(bytes, x).rstrip(b"\n").decode("utf-8")
for x in chain(
iter(cast(IO[bytes], pipe.stdout).readline, b""), check_return_code()
)
)
return self.mapPartitions(func)[docs] def foreach(self: "RDD[T]", f: Callable[[T], None]) -> None: """ Applies a function to all elements of this RDD.
.. versionadded:: 0.7.0
Parameters
----------
f : function
a function applied to each element
See Also
--------
:meth:`RDD.foreachPartition`
:meth:`pyspark.sql.DataFrame.foreach`
:meth:`pyspark.sql.DataFrame.foreachPartition`
Examples
--------
>>> def f(x): print(x)
...
>>> sc.parallelize([1, 2, 3, 4, 5]).foreach(f)
"""
f = fail_on_stopiteration(f)
def processPartition(iterator: Iterable[T]) -> Iterable[Any]:
for x in iterator:
f(x)
return iter([])
self.mapPartitions(processPartition).count() # Force evaluation[docs] def foreachPartition(self: "RDD[T]", f: Callable[[Iterable[T]], None]) -> None: """ Applies a function to each partition of this RDD.
.. versionadded:: 1.0.0
Parameters
----------
f : function
a function applied to each partition
See Also
--------
:meth:`RDD.foreach`
:meth:`pyspark.sql.DataFrame.foreach`
:meth:`pyspark.sql.DataFrame.foreachPartition`
Examples
--------
>>> def f(iterator):
... for x in iterator:
... print(x)
...
>>> sc.parallelize([1, 2, 3, 4, 5]).foreachPartition(f)
"""
def func(it: Iterable[T]) -> Iterable[Any]:
r = f(it)
try:
return iter(r) # type: ignore[call-overload]
except TypeError:
return iter([])
self.mapPartitions(func).count() # Force evaluation[docs] def collect(self: "RDD[T]") -> List[T]: """ Return a list that contains all the elements in this RDD.
.. versionadded:: 0.7.0
Returns
-------
list
a list containing all the elements
Notes
-----
This method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
See Also
--------
:meth:`RDD.toLocalIterator`
:meth:`pyspark.sql.DataFrame.collect`
Examples
--------
>>> sc.range(5).collect()
[0, 1, 2, 3, 4]
>>> sc.parallelize(["x", "y", "z"]).collect()
['x', 'y', 'z']
"""
with SCCallSiteSync(self.context):
assert self.ctx._jvm is not None
sock_info = self.ctx._jvm.PythonRDD.collectAndServe(self._jrdd.rdd())
return list(_load_from_socket(sock_info, self._jrdd_deserializer))[docs] def collectWithJobGroup( self: "RDD[T]", groupId: str, description: str, interruptOnCancel: bool = False ) -> "List[T]": """ When collect rdd, use this method to specify job group.
.. versionadded:: 3.0.0
.. deprecated:: 3.1.0
Use :class:`pyspark.InheritableThread` with the pinned thread mode enabled.
Parameters
----------
groupId : str
The group ID to assign.
description : str
The description to set for the job group.
interruptOnCancel : bool, optional, default False
whether to interrupt jobs on job cancellation.
Returns
-------
list
a list containing all the elements
See Also
--------
:meth:`RDD.collect`
:meth:`SparkContext.setJobGroup`
"""
warnings.warn(
"Deprecated in 3.1, Use pyspark.InheritableThread with "
"the pinned thread mode enabled.",
FutureWarning,
)
with SCCallSiteSync(self.context):
assert self.ctx._jvm is not None
sock_info = self.ctx._jvm.PythonRDD.collectAndServeWithJobGroup(
self._jrdd.rdd(), groupId, description, interruptOnCancel
)
return list(_load_from_socket(sock_info, self._jrdd_deserializer))[docs] def reduce(self: "RDD[T]", f: Callable[[T, T], T]) -> T: """ Reduces the elements of this RDD using the specified commutative and associative binary operator. Currently reduces partitions locally.
.. versionadded:: 0.7.0
Parameters
----------
f : function
the reduce function
Returns
-------
T
the aggregated result
See Also
--------
:meth:`RDD.treeReduce`
:meth:`RDD.aggregate`
:meth:`RDD.treeAggregate`
Examples
--------
>>> from operator import add
>>> sc.parallelize([1, 2, 3, 4, 5]).reduce(add)
15
>>> sc.parallelize((2 for _ in range(10))).map(lambda x: 1).cache().reduce(add)
10
>>> sc.parallelize([]).reduce(add)
Traceback (most recent call last):
...
ValueError: Can not reduce() empty RDD
"""
f = fail_on_stopiteration(f)
def func(iterator: Iterable[T]) -> Iterable[T]:
iterator = iter(iterator)
try:
initial = next(iterator)
except StopIteration:
return
yield reduce(f, iterator, initial)
vals = self.mapPartitions(func).collect()
if vals:
return reduce(f, vals)
raise ValueError("Can not reduce() empty RDD")[docs] def treeReduce(self: "RDD[T]", f: Callable[[T, T], T], depth: int = 2) -> T: """ Reduces the elements of this RDD in a multi-level tree pattern.
.. versionadded:: 1.3.0
Parameters
----------
f : function
the reduce function
depth : int, optional, default 2
suggested depth of the tree (default: 2)
Returns
-------
T
the aggregated result
See Also
--------
:meth:`RDD.reduce`
:meth:`RDD.aggregate`
:meth:`RDD.treeAggregate`
Examples
--------
>>> add = lambda x, y: x + y
>>> rdd = sc.parallelize([-5, -4, -3, -2, -1, 1, 2, 3, 4], 10)
>>> rdd.treeReduce(add)
-5
>>> rdd.treeReduce(add, 1)
-5
>>> rdd.treeReduce(add, 2)
-5
>>> rdd.treeReduce(add, 5)
-5
>>> rdd.treeReduce(add, 10)
-5
"""
if depth < 1:
raise ValueError("Depth cannot be smaller than 1 but got %d." % depth)
# Use the second entry to indicate whether this is a dummy value.
zeroValue: Tuple[T, bool] = ( # type: ignore[assignment]
None,
True,
)
def op(x: Tuple[T, bool], y: Tuple[T, bool]) -> Tuple[T, bool]:
if x[1]:
return y
elif y[1]:
return x
else:
return f(x[0], y[0]), False
reduced = self.map(lambda x: (x, False)).treeAggregate(zeroValue, op, op, depth)
if reduced[1]:
raise ValueError("Cannot reduce empty RDD.")
return reduced[0][docs] def fold(self: "RDD[T]", zeroValue: T, op: Callable[[T, T], T]) -> T: """ Aggregate the elements of each partition, and then the results for all the partitions, using a given associative function and a neutral "zero value."
The function ``op(t1, t2)`` is allowed to modify ``t1`` and return it
as its result value to avoid object allocation; however, it should not
modify ``t2``.
This behaves somewhat differently from fold operations implemented
for non-distributed collections in functional languages like Scala.
This fold operation may be applied to partitions individually, and then
fold those results into the final result, rather than apply the fold
to each element sequentially in some defined ordering. For functions
that are not commutative, the result may differ from that of a fold
applied to a non-distributed collection.
.. versionadded:: 0.7.0
Parameters
----------
zeroValue : T
the initial value for the accumulated result of each partition
op : function
a function used to both accumulate results within a partition and combine
results from different partitions
Returns
-------
T
the aggregated result
See Also
--------
:meth:`RDD.reduce`
:meth:`RDD.aggregate`
Examples
--------
>>> from operator import add
>>> sc.parallelize([1, 2, 3, 4, 5]).fold(0, add)
15
"""
op = fail_on_stopiteration(op)
def func(iterator: Iterable[T]) -> Iterable[T]:
acc = zeroValue
for obj in iterator:
acc = op(acc, obj)
yield acc
# collecting result of mapPartitions here ensures that the copy of
# zeroValue provided to each partition is unique from the one provided
# to the final reduce call
vals = self.mapPartitions(func).collect()
return reduce(op, vals, zeroValue)[docs] def aggregate( self: "RDD[T]", zeroValue: U, seqOp: Callable[[U, T], U], combOp: Callable[[U, U], U] ) -> U: """ Aggregate the elements of each partition, and then the results for all the partitions, using a given combine functions and a neutral "zero value."
The functions ``op(t1, t2)`` is allowed to modify ``t1`` and return it
as its result value to avoid object allocation; however, it should not
modify ``t2``.
The first function (seqOp) can return a different result type, U, than
the type of this RDD. Thus, we need one operation for merging a T into
an U and one operation for merging two U
.. versionadded:: 1.1.0
Parameters
----------
zeroValue : U
the initial value for the accumulated result of each partition
seqOp : function
a function used to accumulate results within a partition
combOp : function
an associative function used to combine results from different partitions
Returns
-------
U
the aggregated result
See Also
--------
:meth:`RDD.reduce`
:meth:`RDD.fold`
Examples
--------
>>> seqOp = (lambda x, y: (x[0] + y, x[1] + 1))
>>> combOp = (lambda x, y: (x[0] + y[0], x[1] + y[1]))
>>> sc.parallelize([1, 2, 3, 4]).aggregate((0, 0), seqOp, combOp)
(10, 4)
>>> sc.parallelize([]).aggregate((0, 0), seqOp, combOp)
(0, 0)
"""
seqOp = fail_on_stopiteration(seqOp)
combOp = fail_on_stopiteration(combOp)
def func(iterator: Iterable[T]) -> Iterable[U]:
acc = zeroValue
for obj in iterator:
acc = seqOp(acc, obj)
yield acc
# collecting result of mapPartitions here ensures that the copy of
# zeroValue provided to each partition is unique from the one provided
# to the final reduce call
vals = self.mapPartitions(func).collect()
return reduce(combOp, vals, zeroValue)[docs] def treeAggregate( self: "RDD[T]", zeroValue: U, seqOp: Callable[[U, T], U], combOp: Callable[[U, U], U], depth: int = 2, ) -> U: """ Aggregates the elements of this RDD in a multi-level tree pattern.
.. versionadded:: 1.3.0
Parameters
----------
zeroValue : U
the initial value for the accumulated result of each partition
seqOp : function
a function used to accumulate results within a partition
combOp : function
an associative function used to combine results from different partitions
depth : int, optional, default 2
suggested depth of the tree
Returns
-------
U
the aggregated result
See Also
--------
:meth:`RDD.aggregate`
:meth:`RDD.treeReduce`
Examples
--------
>>> add = lambda x, y: x + y
>>> rdd = sc.parallelize([-5, -4, -3, -2, -1, 1, 2, 3, 4], 10)
>>> rdd.treeAggregate(0, add, add)
-5
>>> rdd.treeAggregate(0, add, add, 1)
-5
>>> rdd.treeAggregate(0, add, add, 2)
-5
>>> rdd.treeAggregate(0, add, add, 5)
-5
>>> rdd.treeAggregate(0, add, add, 10)
-5
"""
if depth < 1:
raise ValueError("Depth cannot be smaller than 1 but got %d." % depth)
if self.getNumPartitions() == 0:
return zeroValue
def aggregatePartition(iterator: Iterable[T]) -> Iterable[U]:
acc = zeroValue
for obj in iterator:
acc = seqOp(acc, obj)
yield acc
partiallyAggregated = self.mapPartitions(aggregatePartition)
numPartitions = partiallyAggregated.getNumPartitions()
scale = max(int(ceil(pow(numPartitions, 1.0 / depth))), 2)
# If creating an extra level doesn't help reduce the wall-clock time, we stop the tree
# aggregation.
while numPartitions > scale + numPartitions / scale:
numPartitions /= scale # type: ignore[assignment]
curNumPartitions = int(numPartitions)
def mapPartition(i: int, iterator: Iterable[U]) -> Iterable[Tuple[int, U]]:
for obj in iterator:
yield (i % curNumPartitions, obj)
partiallyAggregated = (
partiallyAggregated.mapPartitionsWithIndex(mapPartition)
.reduceByKey(combOp, curNumPartitions)
.values()
)
return partiallyAggregated.reduce(combOp)
@overload
def max(self: "RDD[S]") -> "S":
...
@overload
def max(self: "RDD[T]", key: Callable[[T], "S"]) -> T:
...[docs] def max(self: "RDD[T]", key: Optional[Callable[[T], "S"]] = None) -> T: """ Find the maximum item in this RDD.
.. versionadded:: 1.0.0
Parameters
----------
key : function, optional
A function used to generate key for comparing
Returns
-------
T
the maximum item
See Also
--------
:meth:`RDD.min`
Examples
--------
>>> rdd = sc.parallelize([1.0, 5.0, 43.0, 10.0])
>>> rdd.max()
43.0
>>> rdd.max(key=str)
5.0
"""
if key is None:
return self.reduce(max) # type: ignore[arg-type]
return self.reduce(lambda a, b: max(a, b, key=key)) # type: ignore[arg-type]
@overload
def min(self: "RDD[S]") -> "S":
...
@overload
def min(self: "RDD[T]", key: Callable[[T], "S"]) -> T:
...[docs] def min(self: "RDD[T]", key: Optional[Callable[[T], "S"]] = None) -> T: """ Find the minimum item in this RDD.
.. versionadded:: 1.0.0
Parameters
----------
key : function, optional
A function used to generate key for comparing
Returns
-------
T
the minimum item
See Also
--------
:meth:`RDD.max`
Examples
--------
>>> rdd = sc.parallelize([2.0, 5.0, 43.0, 10.0])
>>> rdd.min()
2.0
>>> rdd.min(key=str)
10.0
"""
if key is None:
return self.reduce(min) # type: ignore[arg-type]
return self.reduce(lambda a, b: min(a, b, key=key)) # type: ignore[arg-type][docs] def sum(self: "RDD[NumberOrArray]") -> "NumberOrArray": """ Add up the elements in this RDD.
.. versionadded:: 0.7.0
Returns
-------
float, int, or complex
the sum of all elements
See Also
--------
:meth:`RDD.mean`
:meth:`RDD.sumApprox`
Examples
--------
>>> sc.parallelize([1.0, 2.0, 3.0]).sum()
6.0
"""
return self.mapPartitions(lambda x: [sum(x)]).fold( # type: ignore[return-value]
0, operator.add
)[docs] def count(self) -> int: """ Return the number of elements in this RDD.
.. versionadded:: 0.7.0
Returns
-------
int
the number of elements
See Also
--------
:meth:`RDD.countApprox`
:meth:`pyspark.sql.DataFrame.count`
Examples
--------
>>> sc.parallelize([2, 3, 4]).count()
3
"""
return self.mapPartitions(lambda i: [sum(1 for _ in i)]).sum()[docs] def stats(self: "RDD[NumberOrArray]") -> StatCounter:
"""
Return a :class:StatCounter object that captures the mean, variance
and count of the RDD's elements in one operation.
.. versionadded:: 0.9.1
Returns
-------
:class:`StatCounter`
a :class:`StatCounter` capturing the mean, variance and count of all elements
See Also
--------
:meth:`RDD.stdev`
:meth:`RDD.sampleStdev`
:meth:`RDD.variance`
:meth:`RDD.sampleVariance`
:meth:`RDD.histogram`
:meth:`pyspark.sql.DataFrame.stat`
"""
def redFunc(left_counter: StatCounter, right_counter: StatCounter) -> StatCounter:
return left_counter.mergeStats(right_counter)
return self.mapPartitions(lambda i: [StatCounter(i)]).reduce( # type: ignore[arg-type]
redFunc
)[docs] def histogram( self: "RDD[S]", buckets: Union[int, List["S"], Tuple["S", ...]] ) -> Tuple[Sequence["S"], List[int]]: """ Compute a histogram using the provided buckets. The buckets are all open to the right except for the last which is closed. e.g. [1,10,20,50] means the buckets are [1,10) [10,20) [20,50], which means 1<=x<10, 10<=x<20, 20<=x<=50. And on the input of 1 and 50 we would have a histogram of 1,0,1.
If your histogram is evenly spaced (e.g. [0, 10, 20, 30]),
this can be switched from an O(log n) insertion to O(1) per
element (where n is the number of buckets).
Buckets must be sorted, not contain any duplicates, and have
at least two elements.
If `buckets` is a number, it will generate buckets which are
evenly spaced between the minimum and maximum of the RDD. For
example, if the min value is 0 and the max is 100, given `buckets`
as 2, the resulting buckets will be [0,50) [50,100]. `buckets` must
be at least 1. An exception is raised if the RDD contains infinity.
If the elements in the RDD do not vary (max == min), a single bucket
will be used.
.. versionadded:: 1.2.0
Parameters
----------
buckets : int, or list, or tuple
if `buckets` is a number, it computes a histogram of the data using
`buckets` number of buckets evenly, otherwise, `buckets` is the provided
buckets to bin the data.
Returns
-------
tuple
a tuple of buckets and histogram
See Also
--------
:meth:`RDD.stats`
Examples
--------
>>> rdd = sc.parallelize(range(51))
>>> rdd.histogram(2)
([0, 25, 50], [25, 26])
>>> rdd.histogram([0, 5, 25, 50])
([0, 5, 25, 50], [5, 20, 26])
>>> rdd.histogram([0, 15, 30, 45, 60]) # evenly spaced buckets
([0, 15, 30, 45, 60], [15, 15, 15, 6])
>>> rdd = sc.parallelize(["ab", "ac", "b", "bd", "ef"])
>>> rdd.histogram(("a", "b", "c"))
(('a', 'b', 'c'), [2, 2])
"""
if isinstance(buckets, int):
if buckets < 1:
raise ValueError("number of buckets must be >= 1")
# filter out non-comparable elements
def comparable(x: Any) -> bool:
if x is None:
return False
if type(x) is float and isnan(x):
return False
return True
filtered = self.filter(comparable)
# faster than stats()
def minmax(a: Tuple["S", "S"], b: Tuple["S", "S"]) -> Tuple["S", "S"]:
return min(a[0], b[0]), max(a[1], b[1])
try:
minv, maxv = filtered.map(lambda x: (x, x)).reduce(minmax)
except TypeError as e:
if " empty " in str(e):
raise ValueError("can not generate buckets from empty RDD")
raise
if minv == maxv or buckets == 1:
return [minv, maxv], [filtered.count()]
try:
inc = (maxv - minv) / buckets # type: ignore[operator]
except TypeError:
raise TypeError("Can not generate buckets with non-number in RDD")
if isinf(inc):
raise ValueError("Can not generate buckets with infinite value")
# keep them as integer if possible
inc = int(inc)
if inc * buckets != maxv - minv: # type: ignore[operator]
inc = (maxv - minv) * 1.0 / buckets # type: ignore[operator]
buckets = [i * inc + minv for i in range(buckets)]
buckets.append(maxv) # fix accumulated error
even = True
elif isinstance(buckets, (list, tuple)):
if len(buckets) < 2:
raise ValueError("buckets should have more than one value")
if any(i is None or isinstance(i, float) and isnan(i) for i in buckets):
raise ValueError("can not have None or NaN in buckets")
if sorted(buckets) != list(buckets):
raise ValueError("buckets should be sorted")
if len(set(buckets)) != len(buckets):
raise ValueError("buckets should not contain duplicated values")
minv = buckets[0]
maxv = buckets[-1]
even = False
inc = None
try:
steps = [
buckets[i + 1] - buckets[i] # type: ignore[operator]
for i in range(len(buckets) - 1)
]
except TypeError:
pass # objects in buckets do not support '-'
else:
if max(steps) - min(steps) < 1e-10: # handle precision errors
even = True
inc = (maxv - minv) / (len(buckets) - 1) # type: ignore[operator]
else:
raise TypeError("buckets should be a list or tuple or number(int or long)")
def histogram(iterator: Iterable["S"]) -> Iterable[List[int]]:
counters = [0] * len(buckets) # type: ignore[arg-type]
for i in iterator:
if i is None or (isinstance(i, float) and isnan(i)) or i > maxv or i < minv:
continue
t = (
int((i - minv) / inc) # type: ignore[operator]
if even
else bisect.bisect_right(buckets, i) - 1 # type: ignore[arg-type]
)
counters[t] += 1
# add last two together
last = counters.pop()
counters[-1] += last
return [counters]
def mergeCounters(a: List[int], b: List[int]) -> List[int]:
return [i + j for i, j in zip(a, b)]
return buckets, self.mapPartitions(histogram).reduce(mergeCounters)[docs] def mean(self: "RDD[NumberOrArray]") -> float: """ Compute the mean of this RDD's elements.
.. versionadded:: 0.9.1
Returns
-------
float
the mean of all elements
See Also
--------
:meth:`RDD.stats`
:meth:`RDD.sum`
:meth:`RDD.meanApprox`
Examples
--------
>>> sc.parallelize([1, 2, 3]).mean()
2.0
"""
return self.stats().mean()[docs] def variance(self: "RDD[NumberOrArray]") -> float: """ Compute the variance of this RDD's elements.
.. versionadded:: 0.9.1
Returns
-------
float
the variance of all elements
See Also
--------
:meth:`RDD.stats`
:meth:`RDD.sampleVariance`
:meth:`RDD.stdev`
:meth:`RDD.sampleStdev`
Examples
--------
>>> sc.parallelize([1, 2, 3]).variance()
0.666...
"""
return self.stats().variance()[docs] def stdev(self: "RDD[NumberOrArray]") -> float: """ Compute the standard deviation of this RDD's elements.
.. versionadded:: 0.9.1
Returns
-------
float
the standard deviation of all elements
See Also
--------
:meth:`RDD.stats`
:meth:`RDD.sampleStdev`
:meth:`RDD.variance`
:meth:`RDD.sampleVariance`
Examples
--------
>>> sc.parallelize([1, 2, 3]).stdev()
0.816...
"""
return self.stats().stdev()[docs] def sampleStdev(self: "RDD[NumberOrArray]") -> float: """ Compute the sample standard deviation of this RDD's elements (which corrects for bias in estimating the standard deviation by dividing by N-1 instead of N).
.. versionadded:: 0.9.1
Returns
-------
float
the sample standard deviation of all elements
See Also
--------
:meth:`RDD.stats`
:meth:`RDD.stdev`
:meth:`RDD.variance`
:meth:`RDD.sampleVariance`
Examples
--------
>>> sc.parallelize([1, 2, 3]).sampleStdev()
1.0
"""
return self.stats().sampleStdev()[docs] def sampleVariance(self: "RDD[NumberOrArray]") -> float: """ Compute the sample variance of this RDD's elements (which corrects for bias in estimating the variance by dividing by N-1 instead of N).
.. versionadded:: 0.9.1
Returns
-------
float
the sample variance of all elements
See Also
--------
:meth:`RDD.stats`
:meth:`RDD.variance`
:meth:`RDD.stdev`
:meth:`RDD.sampleStdev`
Examples
--------
>>> sc.parallelize([1, 2, 3]).sampleVariance()
1.0
"""
return self.stats().sampleVariance()[docs] def countByValue(self: "RDD[K]") -> Dict[K, int]: """ Return the count of each unique value in this RDD as a dictionary of (value, count) pairs.
.. versionadded:: 0.7.0
Returns
-------
dict
a dictionary of (value, count) pairs
See Also
--------
:meth:`RDD.collectAsMap`
:meth:`RDD.countByKey`
Examples
--------
>>> sorted(sc.parallelize([1, 2, 1, 2, 2], 2).countByValue().items())
[(1, 2), (2, 3)]
"""
def countPartition(iterator: Iterable[K]) -> Iterable[Dict[K, int]]:
counts: Dict[K, int] = defaultdict(int)
for obj in iterator:
counts[obj] += 1
yield counts
def mergeMaps(m1: Dict[K, int], m2: Dict[K, int]) -> Dict[K, int]:
for k, v in m2.items():
m1[k] += v
return m1
return self.mapPartitions(countPartition).reduce(mergeMaps)
@overload
def top(self: "RDD[S]", num: int) -> List["S"]:
...
@overload
def top(self: "RDD[T]", num: int, key: Callable[[T], "S"]) -> List[T]:
...[docs] def top(self: "RDD[T]", num: int, key: Optional[Callable[[T], "S"]] = None) -> List[T]: """ Get the top N elements from an RDD.
.. versionadded:: 1.0.0
Parameters
----------
num : int
top N
key : function, optional
a function used to generate key for comparing
Returns
-------
list
the top N elements
See Also
--------
:meth:`RDD.takeOrdered`
:meth:`RDD.max`
:meth:`RDD.min`
Notes
-----
This method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
It returns the list sorted in descending order.
Examples
--------
>>> sc.parallelize([10, 4, 2, 12, 3]).top(1)
[12]
>>> sc.parallelize([2, 3, 4, 5, 6], 2).top(2)
[6, 5]
>>> sc.parallelize([10, 4, 2, 12, 3]).top(3, key=str)
[4, 3, 2]
"""
def topIterator(iterator: Iterable[T]) -> Iterable[List[T]]:
yield heapq.nlargest(num, iterator, key=key)
def merge(a: List[T], b: List[T]) -> List[T]:
return heapq.nlargest(num, a + b, key=key)
return self.mapPartitions(topIterator).reduce(merge)
@overload
def takeOrdered(self: "RDD[S]", num: int) -> List["S"]:
...
@overload
def takeOrdered(self: "RDD[T]", num: int, key: Callable[[T], "S"]) -> List[T]:
...[docs] def takeOrdered(self: "RDD[T]", num: int, key: Optional[Callable[[T], "S"]] = None) -> List[T]: """ Get the N elements from an RDD ordered in ascending order or as specified by the optional key function.
.. versionadded:: 1.0.0
Parameters
----------
num : int
top N
key : function, optional
a function used to generate key for comparing
Returns
-------
list
the top N elements
See Also
--------
:meth:`RDD.top`
:meth:`RDD.max`
:meth:`RDD.min`
Notes
-----
This method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
Examples
--------
>>> sc.parallelize([10, 1, 2, 9, 3, 4, 5, 6, 7]).takeOrdered(6)
[1, 2, 3, 4, 5, 6]
>>> sc.parallelize([10, 1, 2, 9, 3, 4, 5, 6, 7], 2).takeOrdered(6, key=lambda x: -x)
[10, 9, 7, 6, 5, 4]
>>> sc.emptyRDD().takeOrdered(3)
[]
"""
if num < 0:
raise ValueError("top N cannot be negative.")
if num == 0 or self.getNumPartitions() == 0:
return []
else:
def merge(a: List[T], b: List[T]) -> List[T]:
return heapq.nsmallest(num, a + b, key)
return self.mapPartitions(lambda it: [heapq.nsmallest(num, it, key)]).reduce(merge)[docs] def take(self: "RDD[T]", num: int) -> List[T]: """ Take the first num elements of the RDD.
It works by first scanning one partition, and use the results from
that partition to estimate the number of additional partitions needed
to satisfy the limit.
Translated from the Scala implementation in RDD#take().
.. versionadded:: 0.7.0
Parameters
----------
num : int
first number of elements
Returns
-------
list
the first `num` elements
See Also
--------
:meth:`RDD.first`
:meth:`pyspark.sql.DataFrame.take`
Notes
-----
This method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
Examples
--------
>>> sc.parallelize([2, 3, 4, 5, 6]).cache().take(2)
[2, 3]
>>> sc.parallelize([2, 3, 4, 5, 6]).take(10)
[2, 3, 4, 5, 6]
>>> sc.parallelize(range(100), 100).filter(lambda x: x > 90).take(3)
[91, 92, 93]
"""
items: List[T] = []
totalParts = self.getNumPartitions()
partsScanned = 0
while len(items) < num and partsScanned < totalParts:
# The number of partitions to try in this iteration.
# It is ok for this number to be greater than totalParts because
# we actually cap it at totalParts in runJob.
numPartsToTry = 1
if partsScanned > 0:
# If we didn't find any rows after the previous iteration,
# quadruple and retry. Otherwise, interpolate the number of
# partitions we need to try, but overestimate it by 50%.
# We also cap the estimation in the end.
if len(items) == 0:
numPartsToTry = partsScanned * 4
else:
# the first parameter of max is >=1 whenever partsScanned >= 2
numPartsToTry = int(1.5 * num * partsScanned / len(items)) - partsScanned
numPartsToTry = min(max(numPartsToTry, 1), partsScanned * 4)
left = num - len(items)
def takeUpToNumLeft(iterator: Iterable[T]) -> Iterable[T]:
iterator = iter(iterator)
taken = 0
while taken < left:
try:
yield next(iterator)
except StopIteration:
return
taken += 1
p = range(partsScanned, min(partsScanned + numPartsToTry, totalParts))
res = self.context.runJob(self, takeUpToNumLeft, p)
items += res
partsScanned += numPartsToTry
return items[:num][docs] def first(self: "RDD[T]") -> T: """ Return the first element in this RDD.
.. versionadded:: 0.7.0
Returns
-------
T
the first element
See Also
--------
:meth:`RDD.take`
:meth:`pyspark.sql.DataFrame.first`
:meth:`pyspark.sql.DataFrame.head`
Examples
--------
>>> sc.parallelize([2, 3, 4]).first()
2
>>> sc.parallelize([]).first()
Traceback (most recent call last):
...
ValueError: RDD is empty
"""
rs = self.take(1)
if rs:
return rs[0]
raise ValueError("RDD is empty")[docs] def isEmpty(self) -> bool: """ Returns true if and only if the RDD contains no elements at all.
.. versionadded:: 1.3.0
Returns
-------
bool
whether the :class:`RDD` is empty
See Also
--------
:meth:`RDD.first`
:meth:`pyspark.sql.DataFrame.isEmpty`
Notes
-----
An RDD may be empty even when it has at least 1 partition.
Examples
--------
>>> sc.parallelize([]).isEmpty()
True
>>> sc.parallelize([1]).isEmpty()
False
"""
return self.getNumPartitions() == 0 or len(self.take(1)) == 0[docs] def saveAsNewAPIHadoopDataset(
self: "RDD[Tuple[K, V]]",
conf: Dict[str, str],
keyConverter: Optional[str] = None,
valueConverter: Optional[str] = None,
) -> None:
"""
Output a Python RDD of key-value pairs (of form RDD[(K, V)]) to any Hadoop file
system, using the new Hadoop OutputFormat API (mapreduce package). Keys/values are
converted for output using either user specified converters or, by default,
"org.apache.spark.api.python.JavaToWritableConverter".
.. versionadded:: 1.1.0
Parameters
----------
conf : dict
Hadoop job configuration
keyConverter : str, optional
fully qualified classname of key converter (None by default)
valueConverter : str, optional
fully qualified classname of value converter (None by default)
See Also
--------
:meth:`SparkContext.newAPIHadoopRDD`
:meth:`RDD.saveAsHadoopDataset`
:meth:`RDD.saveAsHadoopFile`
:meth:`RDD.saveAsNewAPIHadoopFile`
:meth:`RDD.saveAsSequenceFile`
Examples
--------
>>> import os
>>> import tempfile
Set the related classes
>>> output_format_class = "org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat"
>>> input_format_class = "org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat"
>>> key_class = "org.apache.hadoop.io.IntWritable"
>>> value_class = "org.apache.hadoop.io.Text"
>>> with tempfile.TemporaryDirectory() as d:
... path = os.path.join(d, "new_hadoop_file")
...
... # Create the conf for writing
... write_conf = {
... "mapreduce.job.outputformat.class": (output_format_class),
... "mapreduce.job.output.key.class": key_class,
... "mapreduce.job.output.value.class": value_class,
... "mapreduce.output.fileoutputformat.outputdir": path,
... }
...
... # Write a temporary Hadoop file
... rdd = sc.parallelize([(1, ""), (1, "a"), (3, "x")])
... rdd.saveAsNewAPIHadoopDataset(conf=write_conf)
...
... # Create the conf for reading
... read_conf = {"mapreduce.input.fileinputformat.inputdir": path}
...
... # Load this Hadoop file as an RDD
... loaded = sc.newAPIHadoopRDD(input_format_class,
... key_class, value_class, conf=read_conf)
... sorted(loaded.collect())
[(1, ''), (1, 'a'), (3, 'x')]
"""
jconf = self.ctx._dictToJavaMap(conf)
pickledRDD = self._pickled()
assert self.ctx._jvm is not None
self.ctx._jvm.PythonRDD.saveAsHadoopDataset(
pickledRDD._jrdd, True, jconf, keyConverter, valueConverter, True
)[docs] def saveAsNewAPIHadoopFile(
self: "RDD[Tuple[K, V]]",
path: str,
outputFormatClass: str,
keyClass: Optional[str] = None,
valueClass: Optional[str] = None,
keyConverter: Optional[str] = None,
valueConverter: Optional[str] = None,
conf: Optional[Dict[str, str]] = None,
) -> None:
"""
Output a Python RDD of key-value pairs (of form RDD[(K, V)]) to any Hadoop file
system, using the new Hadoop OutputFormat API (mapreduce package). Key and value types
will be inferred if not specified. Keys and values are converted for output using either
user specified converters or "org.apache.spark.api.python.JavaToWritableConverter". The
conf is applied on top of the base Hadoop conf associated with the SparkContext
of this RDD to create a merged Hadoop MapReduce job configuration for saving the data.
.. versionadded:: 1.1.0
Parameters
----------
path : str
path to Hadoop file
outputFormatClass : str
fully qualified classname of Hadoop OutputFormat
(e.g. "org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat")
keyClass : str, optional
fully qualified classname of key Writable class
(e.g. "org.apache.hadoop.io.IntWritable", None by default)
valueClass : str, optional
fully qualified classname of value Writable class
(e.g. "org.apache.hadoop.io.Text", None by default)
keyConverter : str, optional
fully qualified classname of key converter (None by default)
valueConverter : str, optional
fully qualified classname of value converter (None by default)
conf : dict, optional
Hadoop job configuration (None by default)
See Also
--------
:meth:`SparkContext.newAPIHadoopFile`
:meth:`RDD.saveAsHadoopDataset`
:meth:`RDD.saveAsNewAPIHadoopDataset`
:meth:`RDD.saveAsHadoopFile`
:meth:`RDD.saveAsSequenceFile`
Examples
--------
>>> import os
>>> import tempfile
Set the class of output format
>>> output_format_class = "org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat"
>>> with tempfile.TemporaryDirectory() as d:
... path = os.path.join(d, "hadoop_file")
...
... # Write a temporary Hadoop file
... rdd = sc.parallelize([(1, {3.0: "bb"}), (2, {1.0: "aa"}), (3, {2.0: "dd"})])
... rdd.saveAsNewAPIHadoopFile(path, output_format_class)
...
... # Load this Hadoop file as an RDD
... sorted(sc.sequenceFile(path).collect())
[(1, {3.0: 'bb'}), (2, {1.0: 'aa'}), (3, {2.0: 'dd'})]
"""
jconf = self.ctx._dictToJavaMap(conf)
pickledRDD = self._pickled()
assert self.ctx._jvm is not None
self.ctx._jvm.PythonRDD.saveAsNewAPIHadoopFile(
pickledRDD._jrdd,
True,
path,
outputFormatClass,
keyClass,
valueClass,
keyConverter,
valueConverter,
jconf,
)[docs] def saveAsHadoopDataset(
self: "RDD[Tuple[K, V]]",
conf: Dict[str, str],
keyConverter: Optional[str] = None,
valueConverter: Optional[str] = None,
) -> None:
"""
Output a Python RDD of key-value pairs (of form RDD[(K, V)]) to any Hadoop file
system, using the old Hadoop OutputFormat API (mapred package). Keys/values are
converted for output using either user specified converters or, by default,
"org.apache.spark.api.python.JavaToWritableConverter".
.. versionadded:: 1.1.0
Parameters
----------
conf : dict
Hadoop job configuration
keyConverter : str, optional
fully qualified classname of key converter (None by default)
valueConverter : str, optional
fully qualified classname of value converter (None by default)
See Also
--------
:meth:`SparkContext.hadoopRDD`
:meth:`RDD.saveAsNewAPIHadoopDataset`
:meth:`RDD.saveAsHadoopFile`
:meth:`RDD.saveAsNewAPIHadoopFile`
:meth:`RDD.saveAsSequenceFile`
Examples
--------
>>> import os
>>> import tempfile
Set the related classes
>>> output_format_class = "org.apache.hadoop.mapred.TextOutputFormat"
>>> input_format_class = "org.apache.hadoop.mapred.TextInputFormat"
>>> key_class = "org.apache.hadoop.io.IntWritable"
>>> value_class = "org.apache.hadoop.io.Text"
>>> with tempfile.TemporaryDirectory() as d:
... path = os.path.join(d, "old_hadoop_file")
...
... # Create the conf for writing
... write_conf = {
... "mapred.output.format.class": output_format_class,
... "mapreduce.job.output.key.class": key_class,
... "mapreduce.job.output.value.class": value_class,
... "mapreduce.output.fileoutputformat.outputdir": path,
... }
...
... # Write a temporary Hadoop file
... rdd = sc.parallelize([(1, ""), (1, "a"), (3, "x")])
... rdd.saveAsHadoopDataset(conf=write_conf)
...
... # Create the conf for reading
... read_conf = {"mapreduce.input.fileinputformat.inputdir": path}
...
... # Load this Hadoop file as an RDD
... loaded = sc.hadoopRDD(input_format_class, key_class, value_class, conf=read_conf)
... sorted(loaded.collect())
[(0, '1\\t'), (0, '1\\ta'), (0, '3\\tx')]
"""
jconf = self.ctx._dictToJavaMap(conf)
pickledRDD = self._pickled()
assert self.ctx._jvm is not None
self.ctx._jvm.PythonRDD.saveAsHadoopDataset(
pickledRDD._jrdd, True, jconf, keyConverter, valueConverter, False
)[docs] def saveAsHadoopFile(
self: "RDD[Tuple[K, V]]",
path: str,
outputFormatClass: str,
keyClass: Optional[str] = None,
valueClass: Optional[str] = None,
keyConverter: Optional[str] = None,
valueConverter: Optional[str] = None,
conf: Optional[Dict[str, str]] = None,
compressionCodecClass: Optional[str] = None,
) -> None:
"""
Output a Python RDD of key-value pairs (of form RDD[(K, V)]) to any Hadoop file
system, using the old Hadoop OutputFormat API (mapred package). Key and value types
will be inferred if not specified. Keys and values are converted for output using either
user specified converters or "org.apache.spark.api.python.JavaToWritableConverter". The
conf is applied on top of the base Hadoop conf associated with the SparkContext
of this RDD to create a merged Hadoop MapReduce job configuration for saving the data.
.. versionadded:: 1.1.0
Parameters
----------
path : str
path to Hadoop file
outputFormatClass : str
fully qualified classname of Hadoop OutputFormat
(e.g. "org.apache.hadoop.mapred.SequenceFileOutputFormat")
keyClass : str, optional
fully qualified classname of key Writable class
(e.g. "org.apache.hadoop.io.IntWritable", None by default)
valueClass : str, optional
fully qualified classname of value Writable class
(e.g. "org.apache.hadoop.io.Text", None by default)
keyConverter : str, optional
fully qualified classname of key converter (None by default)
valueConverter : str, optional
fully qualified classname of value converter (None by default)
conf : dict, optional
(None by default)
compressionCodecClass : str
fully qualified classname of the compression codec class
i.e. "org.apache.hadoop.io.compress.GzipCodec" (None by default)
See Also
--------
:meth:`SparkContext.hadoopFile`
:meth:`RDD.saveAsNewAPIHadoopFile`
:meth:`RDD.saveAsHadoopDataset`
:meth:`RDD.saveAsNewAPIHadoopDataset`
:meth:`RDD.saveAsSequenceFile`
Examples
--------
>>> import os
>>> import tempfile
Set the related classes
>>> output_format_class = "org.apache.hadoop.mapred.TextOutputFormat"
>>> input_format_class = "org.apache.hadoop.mapred.TextInputFormat"
>>> key_class = "org.apache.hadoop.io.IntWritable"
>>> value_class = "org.apache.hadoop.io.Text"
>>> with tempfile.TemporaryDirectory() as d:
... path = os.path.join(d, "old_hadoop_file")
...
... # Write a temporary Hadoop file
... rdd = sc.parallelize([(1, ""), (1, "a"), (3, "x")])
... rdd.saveAsHadoopFile(path, output_format_class, key_class, value_class)
...
... # Load this Hadoop file as an RDD
... loaded = sc.hadoopFile(path, input_format_class, key_class, value_class)
... sorted(loaded.collect())
[(0, '1\\t'), (0, '1\\ta'), (0, '3\\tx')]
"""
jconf = self.ctx._dictToJavaMap(conf)
pickledRDD = self._pickled()
assert self.ctx._jvm is not None
self.ctx._jvm.PythonRDD.saveAsHadoopFile(
pickledRDD._jrdd,
True,
path,
outputFormatClass,
keyClass,
valueClass,
keyConverter,
valueConverter,
jconf,
compressionCodecClass,
)[docs] def saveAsSequenceFile(
self: "RDD[Tuple[K, V]]", path: str, compressionCodecClass: Optional[str] = None
) -> None:
"""
Output a Python RDD of key-value pairs (of form RDD[(K, V)]) to any Hadoop file
system, using the "org.apache.hadoop.io.Writable" types that we convert from the
RDD's key and value types. The mechanism is as follows:
1. Pickle is used to convert pickled Python RDD into RDD of Java objects.
2. Keys and values of this Java RDD are converted to Writables and written out.
.. versionadded:: 1.1.0
Parameters
----------
path : str
path to sequence file
compressionCodecClass : str, optional
fully qualified classname of the compression codec class
i.e. "org.apache.hadoop.io.compress.GzipCodec" (None by default)
See Also
--------
:meth:`SparkContext.sequenceFile`
:meth:`RDD.saveAsHadoopFile`
:meth:`RDD.saveAsNewAPIHadoopFile`
:meth:`RDD.saveAsHadoopDataset`
:meth:`RDD.saveAsNewAPIHadoopDataset`
:meth:`RDD.saveAsSequenceFile`
Examples
--------
>>> import os
>>> import tempfile
Set the related classes
>>> with tempfile.TemporaryDirectory() as d:
... path = os.path.join(d, "sequence_file")
...
... # Write a temporary sequence file
... rdd = sc.parallelize([(1, ""), (1, "a"), (3, "x")])
... rdd.saveAsSequenceFile(path)
...
... # Load this sequence file as an RDD
... loaded = sc.sequenceFile(path)
... sorted(loaded.collect())
[(1, ''), (1, 'a'), (3, 'x')]
"""
pickledRDD = self._pickled()
assert self.ctx._jvm is not None
self.ctx._jvm.PythonRDD.saveAsSequenceFile(
pickledRDD._jrdd, True, path, compressionCodecClass
)[docs] def saveAsPickleFile(self, path: str, batchSize: int = 10) -> None:
"""
Save this RDD as a SequenceFile of serialized objects. The serializer
used is :class:pyspark.serializers.CPickleSerializer, default batch size
is 10.
.. versionadded:: 1.1.0
Parameters
----------
path : str
path to pickled file
batchSize : int, optional, default 10
the number of Python objects represented as a single Java object.
See Also
--------
:meth:`SparkContext.pickleFile`
Examples
--------
>>> import os
>>> import tempfile
>>> with tempfile.TemporaryDirectory() as d:
... path = os.path.join(d, "pickle_file")
...
... # Write a temporary pickled file
... sc.parallelize(range(10)).saveAsPickleFile(path, 3)
...
... # Load picked file as an RDD
... sorted(sc.pickleFile(path, 3).collect())
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
"""
ser: Serializer
if batchSize == 0:
ser = AutoBatchedSerializer(CPickleSerializer())
else:
ser = BatchedSerializer(CPickleSerializer(), batchSize)
self._reserialize(ser)._jrdd.saveAsObjectFile(path)[docs] def saveAsTextFile(self, path: str, compressionCodecClass: Optional[str] = None) -> None: """ Save this RDD as a text file, using string representations of elements.
.. versionadded:: 0.7.0
Parameters
----------
path : str
path to text file
compressionCodecClass : str, optional
fully qualified classname of the compression codec class
i.e. "org.apache.hadoop.io.compress.GzipCodec" (None by default)
See Also
--------
:meth:`SparkContext.textFile`
:meth:`SparkContext.wholeTextFiles`
Examples
--------
>>> import os
>>> import tempfile
>>> from fileinput import input
>>> from glob import glob
>>> with tempfile.TemporaryDirectory() as d1:
... path1 = os.path.join(d1, "text_file1")
...
... # Write a temporary text file
... sc.parallelize(range(10)).saveAsTextFile(path1)
...
... # Load text file as an RDD
... ''.join(sorted(input(glob(path1 + "/part-0000*"))))
'0\\n1\\n2\\n3\\n4\\n5\\n6\\n7\\n8\\n9\\n'
Empty lines are tolerated when saving to text files.
>>> with tempfile.TemporaryDirectory() as d2:
... path2 = os.path.join(d2, "text2_file2")
...
... # Write another temporary text file
... sc.parallelize(['', 'foo', '', 'bar', '']).saveAsTextFile(path2)
...
... # Load text file as an RDD
... ''.join(sorted(input(glob(path2 + "/part-0000*"))))
'\\n\\n\\nbar\\nfoo\\n'
Using compressionCodecClass
>>> from fileinput import input, hook_compressed
>>> with tempfile.TemporaryDirectory() as d3:
... path3 = os.path.join(d3, "text3")
... codec = "org.apache.hadoop.io.compress.GzipCodec"
...
... # Write another temporary text file with specified codec
... sc.parallelize(['foo', 'bar']).saveAsTextFile(path3, codec)
...
... # Load text file as an RDD
... result = sorted(input(glob(path3 + "/part*.gz"), openhook=hook_compressed))
... ''.join([r.decode('utf-8') if isinstance(r, bytes) else r for r in result])
'bar\\nfoo\\n'
"""
def func(split: int, iterator: Iterable[Any]) -> Iterable[bytes]:
for x in iterator:
if isinstance(x, bytes):
yield x
elif isinstance(x, str):
yield x.encode("utf-8")
else:
yield str(x).encode("utf-8")
keyed = self.mapPartitionsWithIndex(func)
keyed._bypass_serializer = True # type: ignore[attr-defined]
assert self.ctx._jvm is not None
if compressionCodecClass:
compressionCodec = self.ctx._jvm.java.lang.Class.forName(compressionCodecClass)
keyed._jrdd.map(self.ctx._jvm.BytesToString()).saveAsTextFile(path, compressionCodec)
else:
keyed._jrdd.map(self.ctx._jvm.BytesToString()).saveAsTextFile(path)
# Pair functions[docs] def collectAsMap(self: "RDD[Tuple[K, V]]") -> Dict[K, V]: """ Return the key-value pairs in this RDD to the master as a dictionary.
.. versionadded:: 0.7.0
Returns
-------
:class:`dict`
a dictionary of (key, value) pairs
See Also
--------
:meth:`RDD.countByValue`
Notes
-----
This method should only be used if the resulting data is expected
to be small, as all the data is loaded into the driver's memory.
Examples
--------
>>> m = sc.parallelize([(1, 2), (3, 4)]).collectAsMap()
>>> m[1]
2
>>> m[3]
4
"""
return dict(self.collect())[docs] def keys(self: "RDD[Tuple[K, V]]") -> "RDD[K]": """ Return an RDD with the keys of each tuple.
.. versionadded:: 0.7.0
Returns
-------
:class:`RDD`
a :class:`RDD` only containing the keys
See Also
--------
:meth:`RDD.values`
Examples
--------
>>> rdd = sc.parallelize([(1, 2), (3, 4)]).keys()
>>> rdd.collect()
[1, 3]
"""
return self.map(lambda x: x[0])[docs] def values(self: "RDD[Tuple[K, V]]") -> "RDD[V]": """ Return an RDD with the values of each tuple.
.. versionadded:: 0.7.0
Returns
-------
:class:`RDD`
a :class:`RDD` only containing the values
See Also
--------
:meth:`RDD.keys`
Examples
--------
>>> rdd = sc.parallelize([(1, 2), (3, 4)]).values()
>>> rdd.collect()
[2, 4]
"""
return self.map(lambda x: x[1])[docs] def reduceByKey( self: "RDD[Tuple[K, V]]", func: Callable[[V, V], V], numPartitions: Optional[int] = None, partitionFunc: Callable[[K], int] = portable_hash, ) -> "RDD[Tuple[K, V]]": """ Merge the values for each key using an associative and commutative reduce function.
This will also perform the merging locally on each mapper before
sending results to a reducer, similarly to a "combiner" in MapReduce.
Output will be partitioned with `numPartitions` partitions, or
the default parallelism level if `numPartitions` is not specified.
Default partitioner is hash-partition.
.. versionadded:: 1.6.0
Parameters
----------
func : function
the reduce function
numPartitions : int, optional
the number of partitions in new :class:`RDD`
partitionFunc : function, optional, default `portable_hash`
function to compute the partition index
Returns
-------
:class:`RDD`
a :class:`RDD` containing the keys and the aggregated result for each key
See Also
--------
:meth:`RDD.reduceByKeyLocally`
:meth:`RDD.combineByKey`
:meth:`RDD.aggregateByKey`
:meth:`RDD.foldByKey`
:meth:`RDD.groupByKey`
Examples
--------
>>> from operator import add
>>> rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 1)])
>>> sorted(rdd.reduceByKey(add).collect())
[('a', 2), ('b', 1)]
"""
return self.combineByKey(lambda x: x, func, func, numPartitions, partitionFunc)[docs] def reduceByKeyLocally(self: "RDD[Tuple[K, V]]", func: Callable[[V, V], V]) -> Dict[K, V]: """ Merge the values for each key using an associative and commutative reduce function, but return the results immediately to the master as a dictionary.
This will also perform the merging locally on each mapper before
sending results to a reducer, similarly to a "combiner" in MapReduce.
.. versionadded:: 0.7.0
Parameters
----------
func : function
the reduce function
Returns
-------
dict
a dict containing the keys and the aggregated result for each key
See Also
--------
:meth:`RDD.reduceByKey`
:meth:`RDD.aggregateByKey`
Examples
--------
>>> from operator import add
>>> rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 1)])
>>> sorted(rdd.reduceByKeyLocally(add).items())
[('a', 2), ('b', 1)]
"""
func = fail_on_stopiteration(func)
def reducePartition(iterator: Iterable[Tuple[K, V]]) -> Iterable[Dict[K, V]]:
m: Dict[K, V] = {}
for k, v in iterator:
m[k] = func(m[k], v) if k in m else v
yield m
def mergeMaps(m1: Dict[K, V], m2: Dict[K, V]) -> Dict[K, V]:
for k, v in m2.items():
m1[k] = func(m1[k], v) if k in m1 else v
return m1
return self.mapPartitions(reducePartition).reduce(mergeMaps)[docs] def countByKey(self: "RDD[Tuple[K, V]]") -> Dict[K, int]: """ Count the number of elements for each key, and return the result to the master as a dictionary.
.. versionadded:: 0.7.0
Returns
-------
dict
a dictionary of (key, count) pairs
See Also
--------
:meth:`RDD.collectAsMap`
:meth:`RDD.countByValue`
Examples
--------
>>> rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 1)])
>>> sorted(rdd.countByKey().items())
[('a', 2), ('b', 1)]
"""
return self.map(lambda x: x[0]).countByValue()[docs] def join(
self: "RDD[Tuple[K, V]]",
other: "RDD[Tuple[K, U]]",
numPartitions: Optional[int] = None,
) -> "RDD[Tuple[K, Tuple[V, U]]]":
"""
Return an RDD containing all pairs of elements with matching keys in
self and other.
Each pair of elements will be returned as a (k, (v1, v2)) tuple, where
(k, v1) is in `self` and (k, v2) is in `other`.
Performs a hash join across the cluster.
.. versionadded:: 0.7.0
Parameters
----------
other : :class:`RDD`
another :class:`RDD`
numPartitions : int, optional
the number of partitions in new :class:`RDD`
Returns
-------
:class:`RDD`
a :class:`RDD` containing all pairs of elements with matching keys
See Also
--------
:meth:`RDD.leftOuterJoin`
:meth:`RDD.rightOuterJoin`
:meth:`RDD.fullOuterJoin`
:meth:`RDD.cogroup`
:meth:`RDD.groupWith`
:meth:`pyspark.sql.DataFrame.join`
Examples
--------
>>> rdd1 = sc.parallelize([("a", 1), ("b", 4)])
>>> rdd2 = sc.parallelize([("a", 2), ("a", 3)])
>>> sorted(rdd1.join(rdd2).collect())
[('a', (1, 2)), ('a', (1, 3))]
"""
return python_join(self, other, numPartitions)[docs] def leftOuterJoin(
self: "RDD[Tuple[K, V]]",
other: "RDD[Tuple[K, U]]",
numPartitions: Optional[int] = None,
) -> "RDD[Tuple[K, Tuple[V, Optional[U]]]]":
"""
Perform a left outer join of self and other.
For each element (k, v) in `self`, the resulting RDD will either
contain all pairs (k, (v, w)) for w in `other`, or the pair
(k, (v, None)) if no elements in `other` have key k.
Hash-partitions the resulting RDD into the given number of partitions.
.. versionadded:: 0.7.0
Parameters
----------
other : :class:`RDD`
another :class:`RDD`
numPartitions : int, optional
the number of partitions in new :class:`RDD`
Returns
-------
:class:`RDD`
a :class:`RDD` containing all pairs of elements with matching keys
See Also
--------
:meth:`RDD.join`
:meth:`RDD.rightOuterJoin`
:meth:`RDD.fullOuterJoin`
:meth:`pyspark.sql.DataFrame.join`
Examples
--------
>>> rdd1 = sc.parallelize([("a", 1), ("b", 4)])
>>> rdd2 = sc.parallelize([("a", 2)])
>>> sorted(rdd1.leftOuterJoin(rdd2).collect())
[('a', (1, 2)), ('b', (4, None))]
"""
return python_left_outer_join(self, other, numPartitions)[docs] def rightOuterJoin(
self: "RDD[Tuple[K, V]]",
other: "RDD[Tuple[K, U]]",
numPartitions: Optional[int] = None,
) -> "RDD[Tuple[K, Tuple[Optional[V], U]]]":
"""
Perform a right outer join of self and other.
For each element (k, w) in `other`, the resulting RDD will either
contain all pairs (k, (v, w)) for v in this, or the pair (k, (None, w))
if no elements in `self` have key k.
Hash-partitions the resulting RDD into the given number of partitions.
.. versionadded:: 0.7.0
Parameters
----------
other : :class:`RDD`
another :class:`RDD`
numPartitions : int, optional
the number of partitions in new :class:`RDD`
Returns
-------
:class:`RDD`
a :class:`RDD` containing all pairs of elements with matching keys
See Also
--------
:meth:`RDD.join`
:meth:`RDD.leftOuterJoin`
:meth:`RDD.fullOuterJoin`
:meth:`pyspark.sql.DataFrame.join`
Examples
--------
>>> rdd1 = sc.parallelize([("a", 1), ("b", 4)])
>>> rdd2 = sc.parallelize([("a", 2)])
>>> sorted(rdd2.rightOuterJoin(rdd1).collect())
[('a', (2, 1)), ('b', (None, 4))]
"""
return python_right_outer_join(self, other, numPartitions)[docs] def fullOuterJoin(
self: "RDD[Tuple[K, V]]",
other: "RDD[Tuple[K, U]]",
numPartitions: Optional[int] = None,
) -> "RDD[Tuple[K, Tuple[Optional[V], Optional[U]]]]":
"""
Perform a right outer join of self and other.
For each element (k, v) in `self`, the resulting RDD will either
contain all pairs (k, (v, w)) for w in `other`, or the pair
(k, (v, None)) if no elements in `other` have key k.
Similarly, for each element (k, w) in `other`, the resulting RDD will
either contain all pairs (k, (v, w)) for v in `self`, or the pair
(k, (None, w)) if no elements in `self` have key k.
Hash-partitions the resulting RDD into the given number of partitions.
.. versionadded:: 1.2.0
Parameters
----------
other : :class:`RDD`
another :class:`RDD`
numPartitions : int, optional
the number of partitions in new :class:`RDD`
Returns
-------
:class:`RDD`
a :class:`RDD` containing all pairs of elements with matching keys
See Also
--------
:meth:`RDD.join`
:meth:`RDD.leftOuterJoin`
:meth:`RDD.fullOuterJoin`
:meth:`pyspark.sql.DataFrame.join`
Examples
--------
>>> rdd1 = sc.parallelize([("a", 1), ("b", 4)])
>>> rdd2 = sc.parallelize([("a", 2), ("c", 8)])
>>> sorted(rdd1.fullOuterJoin(rdd2).collect())
[('a', (1, 2)), ('b', (4, None)), ('c', (None, 8))]
"""
return python_full_outer_join(self, other, numPartitions)
# TODO: add option to control map-side combining
# portable_hash is used as default, because builtin hash of None is different
# cross machines.[docs] def partitionBy( self: "RDD[Tuple[K, V]]", numPartitions: Optional[int], partitionFunc: Callable[[K], int] = portable_hash, ) -> "RDD[Tuple[K, V]]": """ Return a copy of the RDD partitioned using the specified partitioner.
.. versionadded:: 0.7.0
Parameters
----------
numPartitions : int, optional
the number of partitions in new :class:`RDD`
partitionFunc : function, optional, default `portable_hash`
function to compute the partition index
Returns
-------
:class:`RDD`
a :class:`RDD` partitioned using the specified partitioner
See Also
--------
:meth:`RDD.repartition`
:meth:`RDD.repartitionAndSortWithinPartitions`
Examples
--------
>>> pairs = sc.parallelize([1, 2, 3, 4, 2, 4, 1]).map(lambda x: (x, x))
>>> sets = pairs.partitionBy(2).glom().collect()
>>> len(set(sets[0]).intersection(set(sets[1])))
0
"""
if numPartitions is None:
numPartitions = self._defaultReducePartitions()
partitioner = Partitioner(numPartitions, partitionFunc)
if self.partitioner == partitioner:
return self
# Transferring O(n) objects to Java is too expensive.
# Instead, we'll form the hash buckets in Python,
# transferring O(numPartitions) objects to Java.
# Each object is a (splitNumber, [objects]) pair.
# In order to avoid too huge objects, the objects are
# grouped into chunks.
outputSerializer = self.ctx._unbatched_serializer
limit = self._memory_limit() / 2
def add_shuffle_key(split: int, iterator: Iterable[Tuple[K, V]]) -> Iterable[bytes]:
buckets = defaultdict(list)
c, batch = 0, min(10 * numPartitions, 1000) # type: ignore[operator]
for k, v in iterator:
buckets[partitionFunc(k) % numPartitions].append((k, v)) # type: ignore[operator]
c += 1
# check used memory and avg size of chunk of objects
if c % 1000 == 0 and get_used_memory() > limit or c > batch:
n, size = len(buckets), 0
for split in list(buckets.keys()):
yield pack_long(split)
d = outputSerializer.dumps(buckets[split])
del buckets[split]
yield d
size += len(d)
avg = int(size / n) >> 20
# let 1M < avg < 10M
if avg < 1:
batch = min(sys.maxsize, batch * 1.5) # type: ignore[assignment]
elif avg > 10:
batch = max(int(batch / 1.5), 1)
c = 0
for split, items in buckets.items():
yield pack_long(split)
yield outputSerializer.dumps(items)
keyed = self.mapPartitionsWithIndex(add_shuffle_key, preservesPartitioning=True)
keyed._bypass_serializer = True # type: ignore[attr-defined]
assert self.ctx._jvm is not None
with SCCallSiteSync(self.context):
pairRDD = self.ctx._jvm.PairwiseRDD(keyed._jrdd.rdd()).asJavaPairRDD()
jpartitioner = self.ctx._jvm.PythonPartitioner(numPartitions, id(partitionFunc))
jrdd = self.ctx._jvm.PythonRDD.valueOfPair(pairRDD.partitionBy(jpartitioner))
rdd: "RDD[Tuple[K, V]]" = RDD(jrdd, self.ctx, BatchedSerializer(outputSerializer))
rdd.partitioner = partitioner
return rdd
# TODO: add control over map-side aggregation[docs] def combineByKey( self: "RDD[Tuple[K, V]]", createCombiner: Callable[[V], U], mergeValue: Callable[[U, V], U], mergeCombiners: Callable[[U, U], U], numPartitions: Optional[int] = None, partitionFunc: Callable[[K], int] = portable_hash, ) -> "RDD[Tuple[K, U]]": """ Generic function to combine the elements for each key using a custom set of aggregation functions.
Turns an RDD[(K, V)] into a result of type RDD[(K, C)], for a "combined
type" C.
To avoid memory allocation, both mergeValue and mergeCombiners are allowed to
modify and return their first argument instead of creating a new C.
In addition, users can control the partitioning of the output RDD.
.. versionadded:: 0.7.0
Parameters
----------
createCombiner : function
a function to turns a V into a C
mergeValue : function
a function to merge a V into a C
mergeCombiners : function
a function to combine two C's into a single one
numPartitions : int, optional
the number of partitions in new :class:`RDD`
partitionFunc : function, optional, default `portable_hash`
function to compute the partition index
Returns
-------
:class:`RDD`
a :class:`RDD` containing the keys and the aggregated result for each key
See Also
--------
:meth:`RDD.reduceByKey`
:meth:`RDD.aggregateByKey`
:meth:`RDD.foldByKey`
:meth:`RDD.groupByKey`
Notes
-----
V and C can be different -- for example, one might group an RDD of type
(Int, Int) into an RDD of type (Int, List[Int]).
Examples
--------
>>> rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 2)])
>>> def to_list(a):
... return [a]
...
>>> def append(a, b):
... a.append(b)
... return a
...
>>> def extend(a, b):
... a.extend(b)
... return a
...
>>> sorted(rdd.combineByKey(to_list, append, extend).collect())
[('a', [1, 2]), ('b', [1])]
"""
if numPartitions is None:
numPartitions = self._defaultReducePartitions()
serializer = self.ctx.serializer
memory = self._memory_limit()
agg = Aggregator(createCombiner, mergeValue, mergeCombiners)
def combineLocally(iterator: Iterable[Tuple[K, V]]) -> Iterable[Tuple[K, U]]:
merger = ExternalMerger(agg, memory * 0.9, serializer)
merger.mergeValues(iterator)
return merger.items()
locally_combined = self.mapPartitions(combineLocally, preservesPartitioning=True)
shuffled = locally_combined.partitionBy(numPartitions, partitionFunc)
def _mergeCombiners(iterator: Iterable[Tuple[K, U]]) -> Iterable[Tuple[K, U]]:
merger = ExternalMerger(agg, memory, serializer)
merger.mergeCombiners(iterator)
return merger.items()
return shuffled.mapPartitions(_mergeCombiners, preservesPartitioning=True)[docs] def aggregateByKey( self: "RDD[Tuple[K, V]]", zeroValue: U, seqFunc: Callable[[U, V], U], combFunc: Callable[[U, U], U], numPartitions: Optional[int] = None, partitionFunc: Callable[[K], int] = portable_hash, ) -> "RDD[Tuple[K, U]]": """ Aggregate the values of each key, using given combine functions and a neutral "zero value". This function can return a different result type, U, than the type of the values in this RDD, V. Thus, we need one operation for merging a V into a U and one operation for merging two U's, The former operation is used for merging values within a partition, and the latter is used for merging values between partitions. To avoid memory allocation, both of these functions are allowed to modify and return their first argument instead of creating a new U.
.. versionadded:: 1.1.0
Parameters
----------
zeroValue : U
the initial value for the accumulated result of each partition
seqFunc : function
a function to merge a V into a U
combFunc : function
a function to combine two U's into a single one
numPartitions : int, optional
the number of partitions in new :class:`RDD`
partitionFunc : function, optional, default `portable_hash`
function to compute the partition index
Returns
-------
:class:`RDD`
a :class:`RDD` containing the keys and the aggregated result for each key
See Also
--------
:meth:`RDD.reduceByKey`
:meth:`RDD.combineByKey`
:meth:`RDD.foldByKey`
:meth:`RDD.groupByKey`
Examples
--------
>>> rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 2)])
>>> seqFunc = (lambda x, y: (x[0] + y, x[1] + 1))
>>> combFunc = (lambda x, y: (x[0] + y[0], x[1] + y[1]))
>>> sorted(rdd.aggregateByKey((0, 0), seqFunc, combFunc).collect())
[('a', (3, 2)), ('b', (1, 1))]
"""
def createZero() -> U:
return copy.deepcopy(zeroValue)
return self.combineByKey(
lambda v: seqFunc(createZero(), v), seqFunc, combFunc, numPartitions, partitionFunc
)[docs] def foldByKey( self: "RDD[Tuple[K, V]]", zeroValue: V, func: Callable[[V, V], V], numPartitions: Optional[int] = None, partitionFunc: Callable[[K], int] = portable_hash, ) -> "RDD[Tuple[K, V]]": """ Merge the values for each key using an associative function "func" and a neutral "zeroValue" which may be added to the result an arbitrary number of times, and must not change the result (e.g., 0 for addition, or 1 for multiplication.).
.. versionadded:: 1.1.0
Parameters
----------
zeroValue : V
the initial value for the accumulated result of each partition
func : function
a function to combine two V's into a single one
numPartitions : int, optional
the number of partitions in new :class:`RDD`
partitionFunc : function, optional, default `portable_hash`
function to compute the partition index
Returns
-------
:class:`RDD`
a :class:`RDD` containing the keys and the aggregated result for each key
See Also
--------
:meth:`RDD.reduceByKey`
:meth:`RDD.combineByKey`
:meth:`RDD.aggregateByKey`
:meth:`RDD.groupByKey`
Examples
--------
>>> rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 1)])
>>> from operator import add
>>> sorted(rdd.foldByKey(0, add).collect())
[('a', 2), ('b', 1)]
"""
def createZero() -> V:
return copy.deepcopy(zeroValue)
return self.combineByKey(
lambda v: func(createZero(), v), func, func, numPartitions, partitionFunc
)
def _memory_limit(self) -> int:
return _parse_memory(self.ctx._conf.get("spark.python.worker.memory", "512m"))
# TODO: support variant with custom partitioner[docs] def groupByKey( self: "RDD[Tuple[K, V]]", numPartitions: Optional[int] = None, partitionFunc: Callable[[K], int] = portable_hash, ) -> "RDD[Tuple[K, Iterable[V]]]": """ Group the values for each key in the RDD into a single sequence. Hash-partitions the resulting RDD with numPartitions partitions.
.. versionadded:: 0.7.0
Parameters
----------
numPartitions : int, optional
the number of partitions in new :class:`RDD`
partitionFunc : function, optional, default `portable_hash`
function to compute the partition index
Returns
-------
:class:`RDD`
a :class:`RDD` containing the keys and the grouped result for each key
See Also
--------
:meth:`RDD.reduceByKey`
:meth:`RDD.combineByKey`
:meth:`RDD.aggregateByKey`
:meth:`RDD.foldByKey`
Notes
-----
If you are grouping in order to perform an aggregation (such as a
sum or average) over each key, using reduceByKey or aggregateByKey will
provide much better performance.
Examples
--------
>>> rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 1)])
>>> sorted(rdd.groupByKey().mapValues(len).collect())
[('a', 2), ('b', 1)]
>>> sorted(rdd.groupByKey().mapValues(list).collect())
[('a', [1, 1]), ('b', [1])]
"""
def createCombiner(x: V) -> List[V]:
return [x]
def mergeValue(xs: List[V], x: V) -> List[V]:
xs.append(x)
return xs
def mergeCombiners(a: List[V], b: List[V]) -> List[V]:
a.extend(b)
return a
memory = self._memory_limit()
serializer = self._jrdd_deserializer
agg = Aggregator(createCombiner, mergeValue, mergeCombiners)
def combine(iterator: Iterable[Tuple[K, V]]) -> Iterable[Tuple[K, List[V]]]:
merger = ExternalMerger(agg, memory * 0.9, serializer)
merger.mergeValues(iterator)
return merger.items()
locally_combined = self.mapPartitions(combine, preservesPartitioning=True)
shuffled = locally_combined.partitionBy(numPartitions, partitionFunc)
def groupByKey(it: Iterable[Tuple[K, List[V]]]) -> Iterable[Tuple[K, List[V]]]:
merger = ExternalGroupBy(agg, memory, serializer)
merger.mergeCombiners(it)
return merger.items()
return shuffled.mapPartitions(groupByKey, True).mapValues(ResultIterable)[docs] def flatMapValues( self: "RDD[Tuple[K, V]]", f: Callable[[V], Iterable[U]] ) -> "RDD[Tuple[K, U]]": """ Pass each value in the key-value pair RDD through a flatMap function without changing the keys; this also retains the original RDD's partitioning.
.. versionadded:: 0.7.0
Parameters
----------
f : function
a function to turn a V into a sequence of U
Returns
-------
:class:`RDD`
a :class:`RDD` containing the keys and the flat-mapped value
See Also
--------
:meth:`RDD.flatMap`
:meth:`RDD.mapValues`
Examples
--------
>>> rdd = sc.parallelize([("a", ["x", "y", "z"]), ("b", ["p", "r"])])
>>> def f(x): return x
...
>>> rdd.flatMapValues(f).collect()
[('a', 'x'), ('a', 'y'), ('a', 'z'), ('b', 'p'), ('b', 'r')]
"""
def flat_map_fn(kv: Tuple[K, V]) -> Iterable[Tuple[K, U]]:
return ((kv[0], x) for x in f(kv[1]))
return self.flatMap(flat_map_fn, preservesPartitioning=True)[docs] def mapValues(self: "RDD[Tuple[K, V]]", f: Callable[[V], U]) -> "RDD[Tuple[K, U]]": """ Pass each value in the key-value pair RDD through a map function without changing the keys; this also retains the original RDD's partitioning.
.. versionadded:: 0.7.0
Parameters
----------
f : function
a function to turn a V into a U
Returns
-------
:class:`RDD`
a :class:`RDD` containing the keys and the mapped value
See Also
--------
:meth:`RDD.map`
:meth:`RDD.flatMapValues`
Examples
--------
>>> rdd = sc.parallelize([("a", ["apple", "banana", "lemon"]), ("b", ["grapes"])])
>>> def f(x): return len(x)
...
>>> rdd.mapValues(f).collect()
[('a', 3), ('b', 1)]
"""
def map_values_fn(kv: Tuple[K, V]) -> Tuple[K, U]:
return kv[0], f(kv[1])
return self.map(map_values_fn, preservesPartitioning=True)
@overload
def groupWith(
self: "RDD[Tuple[K, V]]", other: "RDD[Tuple[K, V1]]"
) -> "RDD[Tuple[K, Tuple[ResultIterable[V], ResultIterable[V1]]]]":
...
@overload
def groupWith(
self: "RDD[Tuple[K, V]]", other: "RDD[Tuple[K, V1]]", __o1: "RDD[Tuple[K, V2]]"
) -> "RDD[Tuple[K, Tuple[ResultIterable[V], ResultIterable[V1], ResultIterable[V2]]]]":
...
@overload
def groupWith(
self: "RDD[Tuple[K, V]]",
other: "RDD[Tuple[K, V1]]",
_o1: "RDD[Tuple[K, V2]]",
_o2: "RDD[Tuple[K, V3]]",
) -> """RDD[
Tuple[
K,
Tuple[
ResultIterable[V],
ResultIterable[V1],
ResultIterable[V2],
ResultIterable[V3],
],
]
]""":
...[docs] def groupWith( # type: ignore[misc] self: "RDD[Tuple[Any, Any]]", other: "RDD[Tuple[Any, Any]]", *others: "RDD[Tuple[Any, Any]]" ) -> "RDD[Tuple[Any, Tuple[ResultIterable[Any], ...]]]": """ Alias for cogroup but with support for multiple RDDs.
.. versionadded:: 0.7.0
Parameters
----------
other : :class:`RDD`
another :class:`RDD`
others : :class:`RDD`
other :class:`RDD`\\s
Returns
-------
:class:`RDD`
a :class:`RDD` containing the keys and cogrouped values
See Also
--------
:meth:`RDD.cogroup`
:meth:`RDD.join`
Examples
--------
>>> rdd1 = sc.parallelize([("a", 5), ("b", 6)])
>>> rdd2 = sc.parallelize([("a", 1), ("b", 4)])
>>> rdd3 = sc.parallelize([("a", 2)])
>>> rdd4 = sc.parallelize([("b", 42)])
>>> [(x, tuple(map(list, y))) for x, y in
... sorted(list(rdd1.groupWith(rdd2, rdd3, rdd4).collect()))]
[('a', ([5], [1], [2], [])), ('b', ([6], [4], [], [42]))]
"""
return python_cogroup((self, other) + others, numPartitions=None)
# TODO: add variant with custom partitioner[docs] def cogroup(
self: "RDD[Tuple[K, V]]",
other: "RDD[Tuple[K, U]]",
numPartitions: Optional[int] = None,
) -> "RDD[Tuple[K, Tuple[ResultIterable[V], ResultIterable[U]]]]":
"""
For each key k in self or other, return a resulting RDD that
contains a tuple with the list of values for that key in self as
well as other.
.. versionadded:: 0.7.0
Parameters
----------
other : :class:`RDD`
another :class:`RDD`
Returns
-------
:class:`RDD`
a :class:`RDD` containing the keys and cogrouped values
See Also
--------
:meth:`RDD.groupWith`
:meth:`RDD.join`
Examples
--------
>>> rdd1 = sc.parallelize([("a", 1), ("b", 4)])
>>> rdd2 = sc.parallelize([("a", 2)])
>>> [(x, tuple(map(list, y))) for x, y in sorted(list(rdd1.cogroup(rdd2).collect()))]
[('a', ([1], [2])), ('b', ([4], []))]
"""
return python_cogroup((self, other), numPartitions)[docs] def sampleByKey( self: "RDD[Tuple[K, V]]", withReplacement: bool, fractions: Dict[K, Union[float, int]], seed: Optional[int] = None, ) -> "RDD[Tuple[K, V]]": """ Return a subset of this RDD sampled by key (via stratified sampling). Create a sample of this RDD using variable sampling rates for different keys as specified by fractions, a key to sampling rate map.
.. versionadded:: 0.7.0
Parameters
----------
withReplacement : bool
whether to sample with or without replacement
fractions : dict
map of specific keys to sampling rates
seed : int, optional
seed for the random number generator
Returns
-------
:class:`RDD`
a :class:`RDD` containing the stratified sampling result
See Also
--------
:meth:`RDD.sample`
Examples
--------
>>> fractions = {"a": 0.2, "b": 0.1}
>>> rdd = sc.parallelize(fractions.keys()).cartesian(sc.parallelize(range(0, 1000)))
>>> sample = dict(rdd.sampleByKey(False, fractions, 2).groupByKey().collect())
>>> 100 < len(sample["a"]) < 300 and 50 < len(sample["b"]) < 150
True
>>> max(sample["a"]) <= 999 and min(sample["a"]) >= 0
True
>>> max(sample["b"]) <= 999 and min(sample["b"]) >= 0
True
"""
for fraction in fractions.values():
assert fraction >= 0.0, "Negative fraction value: %s" % fraction
return self.mapPartitionsWithIndex(
RDDStratifiedSampler(withReplacement, fractions, seed).func, True
)[docs] def subtractByKey(
self: "RDD[Tuple[K, V]]",
other: "RDD[Tuple[K, Any]]",
numPartitions: Optional[int] = None,
) -> "RDD[Tuple[K, V]]":
"""
Return each (key, value) pair in self that has no pair with matching
key in other.
.. versionadded:: 0.9.1
Parameters
----------
other : :class:`RDD`
another :class:`RDD`
numPartitions : int, optional
the number of partitions in new :class:`RDD`
Returns
-------
:class:`RDD`
a :class:`RDD` with the pairs from this whose keys are not in `other`
See Also
--------
:meth:`RDD.subtract`
Examples
--------
>>> rdd1 = sc.parallelize([("a", 1), ("b", 4), ("b", 5), ("a", 2)])
>>> rdd2 = sc.parallelize([("a", 3), ("c", None)])
>>> sorted(rdd1.subtractByKey(rdd2).collect())
[('b', 4), ('b', 5)]
"""
def filter_func(pair: Tuple[K, Tuple[V, Any]]) -> bool:
key, (val1, val2) = pair
return val1 and not val2 # type: ignore[return-value]
return (
self.cogroup(other, numPartitions)
.filter(filter_func) # type: ignore[arg-type]
.flatMapValues(lambda x: x[0])
)[docs] def subtract(self: "RDD[T]", other: "RDD[T]", numPartitions: Optional[int] = None) -> "RDD[T]":
"""
Return each value in self that is not contained in other.
.. versionadded:: 0.9.1
Parameters
----------
other : :class:`RDD`
another :class:`RDD`
numPartitions : int, optional
the number of partitions in new :class:`RDD`
Returns
-------
:class:`RDD`
a :class:`RDD` with the elements from this that are not in `other`
See Also
--------
:meth:`RDD.subtractByKey`
Examples
--------
>>> rdd1 = sc.parallelize([("a", 1), ("b", 4), ("b", 5), ("a", 3)])
>>> rdd2 = sc.parallelize([("a", 3), ("c", None)])
>>> sorted(rdd1.subtract(rdd2).collect())
[('a', 1), ('b', 4), ('b', 5)]
"""
# note: here 'True' is just a placeholder
rdd = other.map(lambda x: (x, True))
return self.map(lambda x: (x, True)).subtractByKey(rdd, numPartitions).keys()[docs] def keyBy(self: "RDD[T]", f: Callable[[T], K]) -> "RDD[Tuple[K, T]]":
"""
Creates tuples of the elements in this RDD by applying f.
.. versionadded:: 0.9.1
Parameters
----------
f : function
a function to compute the key
Returns
-------
:class:`RDD`
a :class:`RDD` with the elements from this that are not in `other`
See Also
--------
:meth:`RDD.map`
:meth:`RDD.keys`
:meth:`RDD.values`
Examples
--------
>>> rdd1 = sc.parallelize(range(0,3)).keyBy(lambda x: x*x)
>>> rdd2 = sc.parallelize(zip(range(0,5), range(0,5)))
>>> [(x, list(map(list, y))) for x, y in sorted(rdd1.cogroup(rdd2).collect())]
[(0, [[0], [0]]), (1, [[1], [1]]), (2, [[], [2]]), (3, [[], [3]]), (4, [[2], [4]])]
"""
return self.map(lambda x: (f(x), x))[docs] def repartition(self: "RDD[T]", numPartitions: int) -> "RDD[T]": """ Return a new RDD that has exactly numPartitions partitions.
Can increase or decrease the level of parallelism in this RDD.
Internally, this uses a shuffle to redistribute data.
If you are decreasing the number of partitions in this RDD, consider
using `coalesce`, which can avoid performing a shuffle.
.. versionadded:: 1.0.0
Parameters
----------
numPartitions : int, optional
the number of partitions in new :class:`RDD`
Returns
-------
:class:`RDD`
a :class:`RDD` with exactly numPartitions partitions
See Also
--------
:meth:`RDD.coalesce`
:meth:`RDD.partitionBy`
:meth:`RDD.repartitionAndSortWithinPartitions`
Examples
--------
>>> rdd = sc.parallelize([1,2,3,4,5,6,7], 4)
>>> sorted(rdd.glom().collect())
[[1], [2, 3], [4, 5], [6, 7]]
>>> len(rdd.repartition(2).glom().collect())
2
>>> len(rdd.repartition(10).glom().collect())
10
"""
return self.coalesce(numPartitions, shuffle=True)[docs] def coalesce(self: "RDD[T]", numPartitions: int, shuffle: bool = False) -> "RDD[T]":
"""
Return a new RDD that is reduced into numPartitions partitions.
.. versionadded:: 1.0.0
Parameters
----------
numPartitions : int, optional
the number of partitions in new :class:`RDD`
shuffle : bool, optional, default False
whether to add a shuffle step
Returns
-------
:class:`RDD`
a :class:`RDD` that is reduced into `numPartitions` partitions
See Also
--------
:meth:`RDD.repartition`
Examples
--------
>>> sc.parallelize([1, 2, 3, 4, 5], 3).glom().collect()
[[1], [2, 3], [4, 5]]
>>> sc.parallelize([1, 2, 3, 4, 5], 3).coalesce(1).glom().collect()
[[1, 2, 3, 4, 5]]
"""
if not numPartitions > 0:
raise ValueError("Number of partitions must be positive.")
if shuffle:
# Decrease the batch size in order to distribute evenly the elements across output
# partitions. Otherwise, repartition will possibly produce highly skewed partitions.
batchSize = min(10, self.ctx._batchSize or 1024)
ser = BatchedSerializer(CPickleSerializer(), batchSize)
selfCopy = self._reserialize(ser)
jrdd_deserializer = selfCopy._jrdd_deserializer
jrdd = selfCopy._jrdd.coalesce(numPartitions, shuffle)
else:
jrdd_deserializer = self._jrdd_deserializer
jrdd = self._jrdd.coalesce(numPartitions, shuffle)
return RDD(jrdd, self.ctx, jrdd_deserializer)[docs] def zip(self: "RDD[T]", other: "RDD[U]") -> "RDD[Tuple[T, U]]": """ Zips this RDD with another one, returning key-value pairs with the first element in each RDD second element in each RDD, etc. Assumes that the two RDDs have the same number of partitions and the same number of elements in each partition (e.g. one was made through a map on the other).
.. versionadded:: 1.0.0
Parameters
----------
other : :class:`RDD`
another :class:`RDD`
Returns
-------
:class:`RDD`
a :class:`RDD` containing the zipped key-value pairs
See Also
--------
:meth:`RDD.zipWithIndex`
:meth:`RDD.zipWithUniqueId`
Examples
--------
>>> rdd1 = sc.parallelize(range(0,5))
>>> rdd2 = sc.parallelize(range(1000, 1005))
>>> rdd1.zip(rdd2).collect()
[(0, 1000), (1, 1001), (2, 1002), (3, 1003), (4, 1004)]
"""
def get_batch_size(ser: Serializer) -> int:
if isinstance(ser, BatchedSerializer):
return ser.batchSize
return 1 # not batched
def batch_as(rdd: "RDD[V]", batchSize: int) -> "RDD[V]":
return rdd._reserialize(BatchedSerializer(CPickleSerializer(), batchSize))
my_batch = get_batch_size(self._jrdd_deserializer)
other_batch = get_batch_size(other._jrdd_deserializer)
if my_batch != other_batch or not my_batch:
# use the smallest batchSize for both of them
batchSize = min(my_batch, other_batch)
if batchSize <= 0:
# auto batched or unlimited
batchSize = 100
other = batch_as(other, batchSize)
self = batch_as(self, batchSize)
if self.getNumPartitions() != other.getNumPartitions():
raise ValueError("Can only zip with RDD which has the same number of partitions")
# There will be an Exception in JVM if there are different number
# of items in each partitions.
pairRDD = self._jrdd.zip(other._jrdd)
deserializer = PairDeserializer(self._jrdd_deserializer, other._jrdd_deserializer)
return RDD(pairRDD, self.ctx, deserializer)[docs] def zipWithIndex(self: "RDD[T]") -> "RDD[Tuple[T, int]]": """ Zips this RDD with its element indices.
The ordering is first based on the partition index and then the
ordering of items within each partition. So the first item in
the first partition gets index 0, and the last item in the last
partition receives the largest index.
This method needs to trigger a spark job when this RDD contains
more than one partitions.
.. versionadded:: 1.2.0
Returns
-------
:class:`RDD`
a :class:`RDD` containing the zipped key-index pairs
See Also
--------
:meth:`RDD.zip`
:meth:`RDD.zipWithUniqueId`
Examples
--------
>>> sc.parallelize(["a", "b", "c", "d"], 3).zipWithIndex().collect()
[('a', 0), ('b', 1), ('c', 2), ('d', 3)]
"""
starts = [0]
if self.getNumPartitions() > 1:
nums = self.mapPartitions(lambda it: [sum(1 for i in it)]).collect()
for i in range(len(nums) - 1):
starts.append(starts[-1] + nums[i])
def func(k: int, it: Iterable[T]) -> Iterable[Tuple[T, int]]:
for i, v in enumerate(it, starts[k]):
yield v, i
return self.mapPartitionsWithIndex(func)[docs] def zipWithUniqueId(self: "RDD[T]") -> "RDD[Tuple[T, int]]": """ Zips this RDD with generated unique Long ids.
Items in the kth partition will get ids k, n+k, 2*n+k, ..., where
n is the number of partitions. So there may exist gaps, but this
method won't trigger a spark job, which is different from
:meth:`zipWithIndex`.
.. versionadded:: 1.2.0
Returns
-------
:class:`RDD`
a :class:`RDD` containing the zipped key-UniqueId pairs
See Also
--------
:meth:`RDD.zip`
:meth:`RDD.zipWithIndex`
Examples
--------
>>> sc.parallelize(["a", "b", "c", "d", "e"], 3).zipWithUniqueId().collect()
[('a', 0), ('b', 1), ('c', 4), ('d', 2), ('e', 5)]
"""
n = self.getNumPartitions()
def func(k: int, it: Iterable[T]) -> Iterable[Tuple[T, int]]:
for i, v in enumerate(it):
yield v, i * n + k
return self.mapPartitionsWithIndex(func)[docs] def name(self) -> Optional[str]: """ Return the name of this RDD.
.. versionadded:: 1.0.0
Returns
-------
str
:class:`RDD` name
See Also
--------
:meth:`RDD.setName`
Examples
--------
>>> rdd = sc.range(5)
>>> rdd.name() == None
True
"""
n = self._jrdd.name()
return n if n else None[docs] def setName(self: "RDD[T]", name: str) -> "RDD[T]": """ Assign a name to this RDD.
.. versionadded:: 1.0.0
Parameters
----------
name : str
new name
Returns
-------
:class:`RDD`
the same :class:`RDD` with name updated
See Also
--------
:meth:`RDD.name`
Examples
--------
>>> rdd = sc.parallelize([1, 2])
>>> rdd.setName('I am an RDD').name()
'I am an RDD'
"""
self._jrdd.setName(name)
return self[docs] def toDebugString(self) -> Optional[bytes]: """ A description of this RDD and its recursive dependencies for debugging.
.. versionadded:: 1.0.0
Returns
-------
bytes
debugging information of this :class:`RDD`
Examples
--------
>>> rdd = sc.range(5)
>>> rdd.toDebugString()
b'...PythonRDD...ParallelCollectionRDD...'
"""
debug_string = self._jrdd.toDebugString()
return debug_string.encode("utf-8") if debug_string else None[docs] def getStorageLevel(self) -> StorageLevel: """ Get the RDD's current storage level.
.. versionadded:: 1.0.0
Returns
-------
:class:`StorageLevel`
current :class:`StorageLevel`
See Also
--------
:meth:`RDD.name`
Examples
--------
>>> rdd = sc.parallelize([1,2])
>>> rdd.getStorageLevel()
StorageLevel(False, False, False, False, 1)
>>> print(rdd.getStorageLevel())
Serialized 1x Replicated
"""
java_storage_level = self._jrdd.getStorageLevel()
storage_level = StorageLevel(
java_storage_level.useDisk(),
java_storage_level.useMemory(),
java_storage_level.useOffHeap(),
java_storage_level.deserialized(),
java_storage_level.replication(),
)
return storage_level
def _defaultReducePartitions(self) -> int:
"""
Returns the default number of partitions to use during reduce tasks (e.g., groupBy).
If spark.default.parallelism is set, then we'll use the value from SparkContext
defaultParallelism, otherwise we'll use the number of partitions in this RDD.
This mirrors the behavior of the Scala Partitioner#defaultPartitioner, intended to reduce
the likelihood of OOMs. Once PySpark adopts Partitioner-based APIs, this behavior will
be inherent.
"""
if self.ctx._conf.contains("spark.default.parallelism"):
return self.ctx.defaultParallelism
else:
return self.getNumPartitions()[docs] def lookup(self: "RDD[Tuple[K, V]]", key: K) -> List[V]:
"""
Return the list of values in the RDD for key key. This operation
is done efficiently if the RDD has a known partitioner by only
searching the partition that the key maps to.
.. versionadded:: 1.2.0
Parameters
----------
key : K
the key to look up
Returns
-------
list
the list of values in the :class:`RDD` for key `key`
Examples
--------
>>> l = range(1000)
>>> rdd = sc.parallelize(zip(l, l), 10)
>>> rdd.lookup(42) # slow
[42]
>>> sorted = rdd.sortByKey()
>>> sorted.lookup(42) # fast
[42]
>>> sorted.lookup(1024)
[]
>>> rdd2 = sc.parallelize([(('a', 'b'), 'c')]).groupByKey()
>>> list(rdd2.lookup(('a', 'b'))[0])
['c']
"""
values = self.filter(lambda kv: kv[0] == key).values()
if self.partitioner is not None:
return self.ctx.runJob(values, lambda x: x, [self.partitioner(key)])
return values.collect()
def _to_java_object_rdd(self) -> "JavaObject":
"""Return a JavaRDD of Object by unpickling
It will convert each Python object into Java object by Pickle, whenever the
RDD is serialized in batch or not.
"""
rdd = self._pickled()
assert self.ctx._jvm is not None
return self.ctx._jvm.SerDeUtil.pythonToJava(rdd._jrdd, True)[docs] def countApprox(self, timeout: int, confidence: float = 0.95) -> int: """ Approximate version of count() that returns a potentially incomplete result within a timeout, even if not all tasks have finished.
.. versionadded:: 1.2.0
Parameters
----------
timeout : int
maximum time to wait for the job, in milliseconds
confidence : float
the desired statistical confidence in the result
Returns
-------
int
a potentially incomplete result, with error bounds
See Also
--------
:meth:`RDD.count`
Examples
--------
>>> rdd = sc.parallelize(range(1000), 10)
>>> rdd.countApprox(1000, 1.0)
1000
"""
drdd = self.mapPartitions(lambda it: [float(sum(1 for i in it))])
return int(drdd.sumApprox(timeout, confidence))[docs] def sumApprox( self: "RDD[Union[float, int]]", timeout: int, confidence: float = 0.95 ) -> BoundedFloat: """ Approximate operation to return the sum within a timeout or meet the confidence.
.. versionadded:: 1.2.0
Parameters
----------
timeout : int
maximum time to wait for the job, in milliseconds
confidence : float
the desired statistical confidence in the result
Returns
-------
:class:`BoundedFloat`
a potentially incomplete result, with error bounds
See Also
--------
:meth:`RDD.sum`
Examples
--------
>>> rdd = sc.parallelize(range(1000), 10)
>>> r = sum(range(1000))
>>> abs(rdd.sumApprox(1000) - r) / r < 0.05
True
"""
jrdd = self.mapPartitions(lambda it: [float(sum(it))])._to_java_object_rdd()
assert self.ctx._jvm is not None
jdrdd = self.ctx._jvm.JavaDoubleRDD.fromRDD(jrdd.rdd())
r = jdrdd.sumApprox(timeout, confidence).getFinalValue()
return BoundedFloat(r.mean(), r.confidence(), r.low(), r.high())[docs] def meanApprox( self: "RDD[Union[float, int]]", timeout: int, confidence: float = 0.95 ) -> BoundedFloat: """ Approximate operation to return the mean within a timeout or meet the confidence.
.. versionadded:: 1.2.0
Parameters
----------
timeout : int
maximum time to wait for the job, in milliseconds
confidence : float
the desired statistical confidence in the result
Returns
-------
:class:`BoundedFloat`
a potentially incomplete result, with error bounds
See Also
--------
:meth:`RDD.mean`
Examples
--------
>>> rdd = sc.parallelize(range(1000), 10)
>>> r = sum(range(1000)) / 1000.0
>>> abs(rdd.meanApprox(1000) - r) / r < 0.05
True
"""
jrdd = self.map(float)._to_java_object_rdd()
assert self.ctx._jvm is not None
jdrdd = self.ctx._jvm.JavaDoubleRDD.fromRDD(jrdd.rdd())
r = jdrdd.meanApprox(timeout, confidence).getFinalValue()
return BoundedFloat(r.mean(), r.confidence(), r.low(), r.high())[docs] def countApproxDistinct(self: "RDD[T]", relativeSD: float = 0.05) -> int: """ Return approximate number of distinct elements in the RDD.
.. versionadded:: 1.2.0
Parameters
----------
relativeSD : float, optional
Relative accuracy. Smaller values create
counters that require more space.
It must be greater than 0.000017.
Returns
-------
int
approximate number of distinct elements
See Also
--------
:meth:`RDD.distinct`
Notes
-----
The algorithm used is based on streamlib's implementation of
`"HyperLogLog in Practice: Algorithmic Engineering of a State
of The Art Cardinality Estimation Algorithm", available here
<https://doi.org/10.1145/2452376.2452456>`_.
Examples
--------
>>> n = sc.parallelize(range(1000)).map(str).countApproxDistinct()
>>> 900 < n < 1100
True
>>> n = sc.parallelize([i % 20 for i in range(1000)]).countApproxDistinct()
>>> 16 < n < 24
True
"""
if relativeSD < 0.000017:
raise ValueError("relativeSD should be greater than 0.000017")
# the hash space in Java is 2^32
hashRDD = self.map(lambda x: portable_hash(x) & 0xFFFFFFFF)
return hashRDD._to_java_object_rdd().countApproxDistinct(relativeSD)[docs] def toLocalIterator(self: "RDD[T]", prefetchPartitions: bool = False) -> Iterator[T]: """ Return an iterator that contains all of the elements in this RDD. The iterator will consume as much memory as the largest partition in this RDD. With prefetch it may consume up to the memory of the 2 largest partitions.
.. versionadded:: 1.3.0
Parameters
----------
prefetchPartitions : bool, optional
If Spark should pre-fetch the next partition
before it is needed.
Returns
-------
:class:`collections.abc.Iterator`
an iterator that contains all of the elements in this :class:`RDD`
See Also
--------
:meth:`RDD.collect`
:meth:`pyspark.sql.DataFrame.toLocalIterator`
Examples
--------
>>> rdd = sc.parallelize(range(10))
>>> [x for x in rdd.toLocalIterator()]
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
"""
assert self.ctx._jvm is not None
with SCCallSiteSync(self.context):
sock_info = self.ctx._jvm.PythonRDD.toLocalIteratorAndServe(
self._jrdd.rdd(), prefetchPartitions
)
return _local_iterator_from_socket(sock_info, self._jrdd_deserializer)[docs] def barrier(self: "RDD[T]") -> "RDDBarrier[T]": """ Marks the current stage as a barrier stage, where Spark must launch all tasks together. In case of a task failure, instead of only restarting the failed task, Spark will abort the entire stage and relaunch all tasks for this stage. The barrier execution mode feature is experimental and it only handles limited scenarios. Please read the linked SPIP and design docs to understand the limitations and future plans.
.. versionadded:: 2.4.0
Returns
-------
:class:`RDDBarrier`
instance that provides actions within a barrier stage.
See Also
--------
:class:`pyspark.BarrierTaskContext`
Notes
-----
For additional information see
- `SPIP: Barrier Execution Mode <https://issues.apache.org/jira/browse/SPARK-24374>`_
- `Design Doc <https://issues.apache.org/jira/browse/SPARK-24582>`_
This API is experimental
"""
return RDDBarrier(self)
def _is_barrier(self) -> bool:
"""
Whether this RDD is in a barrier stage.
"""
return self._jrdd.rdd().isBarrier()[docs] def withResources(self: "RDD[T]", profile: ResourceProfile) -> "RDD[T]":
"""
Specify a :class:pyspark.resource.ResourceProfile to use when calculating this RDD.
This is only supported on certain cluster managers and currently requires dynamic
allocation to be enabled. It will result in new executors with the resources specified
being acquired to calculate the RDD.
.. versionadded:: 3.1.0
Parameters
----------
profile : :class:`pyspark.resource.ResourceProfile`
a resource profile
Returns
-------
:class:`RDD`
the same :class:`RDD` with user specified profile
See Also
--------
:meth:`RDD.getResourceProfile`
Notes
-----
This API is experimental
"""
self.has_resource_profile = True
if profile._java_resource_profile is not None:
jrp = profile._java_resource_profile
else:
assert self.ctx._jvm is not None
builder = self.ctx._jvm.org.apache.spark.resource.ResourceProfileBuilder()
ereqs = ExecutorResourceRequests(self.ctx._jvm, profile._executor_resource_requests)
treqs = TaskResourceRequests(self.ctx._jvm, profile._task_resource_requests)
builder.require(ereqs._java_executor_resource_requests)
builder.require(treqs._java_task_resource_requests)
jrp = builder.build()
self._jrdd.withResources(jrp)
return self[docs] def getResourceProfile(self) -> Optional[ResourceProfile]:
"""
Get the :class:pyspark.resource.ResourceProfile specified with this RDD or None
if it wasn't specified.
.. versionadded:: 3.1.0
Returns
-------
class:`pyspark.resource.ResourceProfile`
The user specified profile or None if none were specified
See Also
--------
:meth:`RDD.withResources`
Notes
-----
This API is experimental
"""
rp = self._jrdd.getResourceProfile()
if rp is not None:
return ResourceProfile(_java_resource_profile=rp)
else:
return None
@overload
def toDF(
self: "RDD[RowLike]",
schema: Optional[Union[List[str], Tuple[str, ...]]] = None,
sampleRatio: Optional[float] = None,
) -> "DataFrame":
...
@overload
def toDF(
self: "RDD[RowLike]", schema: Optional[Union["StructType", str]] = None
) -> "DataFrame":
...
@overload
def toDF(
self: "RDD[AtomicValue]",
schema: Union["AtomicType", str],
) -> "DataFrame":
...
def toDF(
self: "RDD[Any]", schema: Optional[Any] = None, sampleRatio: Optional[float] = None
) -> "DataFrame":
raise PySparkRuntimeError(
error_class="CALL_BEFORE_INITIALIZE",
message_parameters={
"func_name": "RDD.toDF",
"object": "SparkSession",
},
)def _prepare_for_python_RDD(sc: "SparkContext", command: Any) -> Tuple[bytes, Any, Any, Any]: # the serialized command will be compressed by broadcast ser = CloudPickleSerializer() pickled_command = ser.dumps(command) assert sc._jvm is not None if len(pickled_command) > sc._jvm.PythonUtils.getBroadcastThreshold(sc._jsc): # Default 1M # The broadcast will have same life cycle as created PythonRDD broadcast = sc.broadcast(pickled_command) pickled_command = ser.dumps(broadcast) broadcast_vars = [x._jbroadcast for x in sc._pickled_broadcast_vars] sc._pickled_broadcast_vars.clear() return pickled_command, broadcast_vars, sc.environment, sc._python_includes
def _wrap_function( sc: "SparkContext", func: Callable, deserializer: Any, serializer: Any, profiler: Any = None ) -> "JavaObject": assert deserializer, "deserializer should not be empty" assert serializer, "serializer should not be empty" command = (func, profiler, deserializer, serializer) pickled_command, broadcast_vars, env, includes = _prepare_for_python_RDD(sc, command) assert sc._jvm is not None return sc._jvm.SimplePythonFunction( bytearray(pickled_command), env, includes, sc.pythonExec, sc.pythonVer, broadcast_vars, sc._javaAccumulator, )
[docs]class RDDBarrier(Generic[T]):
"""
Wraps an RDD in a barrier stage, which forces Spark to launch tasks of this stage together.
:class:`RDDBarrier` instances are created by :meth:`RDD.barrier`.
.. versionadded:: 2.4.0
Notes
-----
This API is experimental
"""
def __init__(self, rdd: RDD[T]):
self.rdd = rdd[docs] def mapPartitions(
self, f: Callable[[Iterable[T]], Iterable[U]], preservesPartitioning: bool = False
) -> RDD[U]:
"""
Returns a new RDD by applying a function to each partition of the wrapped RDD,
where tasks are launched together in a barrier stage.
The interface is the same as :meth:RDD.mapPartitions.
Please see the API doc there.
.. versionadded:: 2.4.0
Parameters
----------
f : function
a function to run on each partition of the RDD
preservesPartitioning : bool, optional, default False
indicates whether the input function preserves the partitioner,
which should be False unless this is a pair RDD and the input
Returns
-------
:class:`RDD`
a new :class:`RDD` by applying a function to each partition
See Also
--------
:meth:`RDD.mapPartitions`
Notes
-----
This API is experimental
Examples
--------
>>> rdd = sc.parallelize([1, 2, 3, 4], 2)
>>> def f(iterator): yield sum(iterator)
...
>>> barrier = rdd.barrier()
>>> barrier
<pyspark.rdd.RDDBarrier ...>
>>> barrier.mapPartitions(f).collect()
[3, 7]
"""
def func(s: int, iterator: Iterable[T]) -> Iterable[U]:
return f(iterator)
return PipelinedRDD(self.rdd, func, preservesPartitioning, isFromBarrier=True)[docs] def mapPartitionsWithIndex(
self,
f: Callable[[int, Iterable[T]], Iterable[U]],
preservesPartitioning: bool = False,
) -> RDD[U]:
"""
Returns a new RDD by applying a function to each partition of the wrapped RDD, while
tracking the index of the original partition. And all tasks are launched together
in a barrier stage.
The interface is the same as :meth:RDD.mapPartitionsWithIndex.
Please see the API doc there.
.. versionadded:: 3.0.0
Parameters
----------
f : function
a function to run on each partition of the RDD
preservesPartitioning : bool, optional, default False
indicates whether the input function preserves the partitioner,
which should be False unless this is a pair RDD and the input
Returns
-------
:class:`RDD`
a new :class:`RDD` by applying a function to each partition
See Also
--------
:meth:`RDD.mapPartitionsWithIndex`
Notes
-----
This API is experimental
Examples
--------
>>> rdd = sc.parallelize([1, 2, 3, 4], 4)
>>> def f(splitIndex, iterator): yield splitIndex
...
>>> barrier = rdd.barrier()
>>> barrier
<pyspark.rdd.RDDBarrier ...>
>>> barrier.mapPartitionsWithIndex(f).sum()
6
"""
return PipelinedRDD(self.rdd, f, preservesPartitioning, isFromBarrier=True)class PipelinedRDD(RDD[U], Generic[T, U]):
"""
Examples
--------
Pipelined maps:
>>> rdd = sc.parallelize([1, 2, 3, 4])
>>> rdd.map(lambda x: 2 * x).cache().map(lambda x: 2 * x).collect()
[4, 8, 12, 16]
>>> rdd.map(lambda x: 2 * x).map(lambda x: 2 * x).collect()
[4, 8, 12, 16]
Pipelined reduces:
>>> from operator import add
>>> rdd.map(lambda x: 2 * x).reduce(add)
20
>>> rdd.flatMap(lambda x: [x, x]).reduce(add)
20
"""
def __init__(
self,
prev: RDD[T],
func: Callable[[int, Iterable[T]], Iterable[U]],
preservesPartitioning: bool = False,
isFromBarrier: bool = False,
):
if not isinstance(prev, PipelinedRDD) or not prev._is_pipelinable():
# This transformation is the first in its stage:
self.func = func
self.preservesPartitioning = preservesPartitioning
self._prev_jrdd = prev._jrdd
self._prev_jrdd_deserializer = prev._jrdd_deserializer
else:
prev_func: Callable[[int, Iterable[V]], Iterable[T]] = prev.func
def pipeline_func(split: int, iterator: Iterable[V]) -> Iterable[U]:
return func(split, prev_func(split, iterator))
self.func = pipeline_func
self.preservesPartitioning = prev.preservesPartitioning and preservesPartitioning
self._prev_jrdd = prev._prev_jrdd # maintain the pipeline
self._prev_jrdd_deserializer = prev._prev_jrdd_deserializer
self.is_cached = False
self.has_resource_profile = False
self.is_checkpointed = False
self.ctx = prev.ctx
self.prev = prev
self._jrdd_val: Optional["JavaObject"] = None
self._id = None
self._jrdd_deserializer = self.ctx.serializer
self._bypass_serializer = False
self.partitioner = prev.partitioner if self.preservesPartitioning else None
self.is_barrier = isFromBarrier or prev._is_barrier()
def getNumPartitions(self) -> int:
return self._prev_jrdd.partitions().size()
@property
def _jrdd(self) -> "JavaObject":
if self._jrdd_val:
return self._jrdd_val
if self._bypass_serializer:
self._jrdd_deserializer = NoOpSerializer()
if (
self.ctx.profiler_collector
and self.ctx._conf.get("spark.python.profile", "false") == "true"
):
profiler = self.ctx.profiler_collector.new_profiler(self.ctx)
else:
profiler = None
wrapped_func = _wrap_function(
self.ctx, self.func, self._prev_jrdd_deserializer, self._jrdd_deserializer, profiler
)
assert self.ctx._jvm is not None
python_rdd = self.ctx._jvm.PythonRDD(
self._prev_jrdd.rdd(), wrapped_func, self.preservesPartitioning, self.is_barrier
)
self._jrdd_val = python_rdd.asJavaRDD()
if profiler:
assert self._jrdd_val is not None
self._id = self._jrdd_val.id()
self.ctx.profiler_collector.add_profiler(self._id, profiler)
return self._jrdd_val
def id(self) -> int:
if self._id is None:
self._id = self._jrdd.id()
return self._id
def _is_pipelinable(self) -> bool:
return not (self.is_cached or self.is_checkpointed or self.has_resource_profile)
def _is_barrier(self) -> bool:
return self.is_barrierdef _test() -> None: import doctest import tempfile from pyspark.context import SparkContext
tmp_dir = tempfile.TemporaryDirectory()
globs = globals().copy()
# The small batch size here ensures that we see multiple batches,
# even in these small test examples:
globs["sc"] = SparkContext("local[4]", "PythonTest")
globs["sc"].setCheckpointDir(tmp_dir.name)
(failure_count, test_count) = doctest.testmod(globs=globs, optionflags=doctest.ELLIPSIS)
globs["sc"].stop()
tmp_dir.cleanup()
if failure_count:
tmp_dir.cleanup()
sys.exit(-1)if name == "main": _test()