pyarrow.FixedSizeBufferWriter — Apache Arrow v20.0.0 (original) (raw)
class pyarrow.FixedSizeBufferWriter#
Bases: NativeFile
A stream writing to a Arrow buffer.
Examples
Create a stream to write to pyarrow.Buffer:
import pyarrow as pa buf = pa.allocate_buffer(5) with pa.output_stream(buf) as stream: ... stream.write(b'abcde') ... stream ... 5 <pyarrow.FixedSizeBufferWriter closed=False own_file=False is_seekable=False is_writable=True is_readable=False>
Inspect the buffer:
buf.to_pybytes() b'abcde' buf <pyarrow.Buffer address=... size=5 is_cpu=True is_mutable=True>
__init__(*args, **kwargs)#
Methods
Attributes
close(self)#
closed#
download(self, stream_or_path, buffer_size=None)#
Read this file completely to a local path or destination stream.
This method first seeks to the beginning of the file.
Parameters:
stream_or_pathstr or file-like object
If a string, a local file path to write to; otherwise, should be a writable stream.
buffer_sizeint, optional
The buffer size to use for data transfers.
fileno(self)#
NOT IMPLEMENTED
flush(self)#
Flush the stream, if applicable.
An error is raised if stream is not writable.
get_stream(self, file_offset, nbytes)#
Return an input stream that reads a file segment independent of the state of the file.
Allows reading portions of a random access file as an input stream without interfering with each other.
Parameters:
file_offsetint
nbytesint
Returns:
streamNativeFile
isatty(self)#
metadata(self)#
Return file metadata
mode#
The file mode. Currently instances of NativeFile may support:
- rb: binary read
- wb: binary write
- rb+: binary read and write
- ab: binary append
read(self, nbytes=None)#
Read and return up to n bytes.
If nbytes is None, then the entire remaining file contents are read.
Parameters:
Returns:
databytes
read1(self, nbytes=None)#
Read and return up to n bytes.
Unlike read(), if nbytes is None then a chunk is read, not the entire file.
Parameters:
The maximum number of bytes to read.
Returns:
databytes
read_at(self, nbytes, offset)#
Read indicated number of bytes at offset from the file
Parameters:
nbytesint
offsetint
Returns:
databytes
read_buffer(self, nbytes=None)#
Read from buffer.
Parameters:
nbytesint, optional
maximum number of bytes read
readable(self)#
readall(self)#
readinto(self, b)#
Read into the supplied buffer
Parameters:
bbuffer-like object
A writable buffer object (such as a bytearray).
Returns:
writtenint
number of bytes written
readline(self, size=None)#
NOT IMPLEMENTED. Read and return a line of bytes from the file.
If size is specified, read at most size bytes.
Line terminator is always b”n”.
Parameters:
sizeint
maximum number of bytes read
readlines(self, hint=None)#
NOT IMPLEMENTED. Read lines of the file
Parameters:
hintint
maximum number of bytes read until we stop
seek(self, int64_t position, int whence=0)#
Change current file stream position
Parameters:
positionint
Byte offset, interpreted relative to value of whence argument
whenceint, default 0
Point of reference for seek offset
Returns:
The new absolute stream position.
Notes
Values of whence: * 0 – start of stream (the default); offset should be zero or positive * 1 – current stream position; offset may be negative * 2 – end of stream; offset is usually negative
seekable(self)#
set_memcopy_blocksize(self, int64_t blocksize)#
Parameters:
blocksizeint64
set_memcopy_threads(self, int num_threads)#
Parameters:
num_threadsint
set_memcopy_threshold(self, int64_t threshold)#
Parameters:
thresholdint64
size(self)#
Return file size
tell(self)#
Return current stream position
truncate(self)#
NOT IMPLEMENTED
upload(self, stream, buffer_size=None)#
Write from a source stream to this file.
Parameters:
streamfile-like object
Source stream to pipe to this file.
buffer_sizeint, optional
The buffer size to use for data transfers.
writable(self)#
write(self, data)#
Write data to the file.
Parameters:
databytes-like object or exporter of buffer protocol
Returns:
nbytes: number of bytes written
writelines(self, lines)#
Write lines to the file.
Parameters:
linesiterable
Iterable of bytes-like objects or exporters of buffer protocol