IterableOnceOps (original) (raw)
scala.collection.IterableOnceOps
This implementation trait can be mixed into an IterableOnce to get the basic methods that are shared between Iterator and Iterable. The IterableOnce must support multiple calls to iterator but may or may not return the same Iterator every time.
Attributes
Source
Graph
Supertypes
Known subtypes
trait Map[K, V]
class ::[A]
trait MapOps[K, V, CC, C]
trait Map[K, V]
trait Map[K, V]
trait MapOps[K, V, CC, C]
class Id[K, V]
class Id[A]
class Id[A]
class Map[A, B]
class Map[A, B]
class Map[A, B]
class Zip[A, B]
trait Map[K, V]
trait MapOps[K, V, CC, C]
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Members list
Builds a new collection by applying a partial function to all elements of this collection on which the function is defined.
Builds a new collection by applying a partial function to all elements of this collection on which the function is defined.
Type parameters
B
the element type of the returned collection.
Value parameters
pf
the partial function which filters and maps the collection.
Attributes
Returns
a new collection resulting from applying the given partial function pf to each element on which it is defined and collecting the results. The order of the elements is preserved.
Source
Selects all elements except the first n ones.
Selects all elements except the first n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
n
the number of elements to drop from this collection.
Attributes
Returns
a collection consisting of all elements of this collection except the first n ones, or else the empty collection, if this collection has less than n elements. If n is negative, don't drop any elements.
Source
Selects all elements except the longest prefix that satisfies a predicate.
Selects all elements except the longest prefix that satisfies a predicate.
The matching prefix starts with the first element of this collection, and the element following the prefix is the first element that does not satisfy the predicate. The matching prefix may be empty, so that this method returns the entire collection.
Example:
scala> List(1, 2, 3, 100, 4).dropWhile(n => n < 10)
val res0: List[Int] = List(100, 4)
scala> List(1, 2, 3, 100, 4).dropWhile(n => n == 0)
val res1: List[Int] = List(1, 2, 3, 100, 4)
Use span to obtain both the prefix and suffix. Use filterNot to drop all elements that satisfy the predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
p
The predicate used to test elements.
Attributes
Returns
the longest suffix of this collection whose first element does not satisfy the predicate p.
Source
Selects all elements of this collection which satisfy a predicate.
Selects all elements of this collection which satisfy a predicate.
Value parameters
p
the predicate used to test elements.
Attributes
Returns
a new collection consisting of all elements of this collection that satisfy the given predicate p. The order of the elements is preserved.
Source
Selects all elements of this collection which do not satisfy a predicate.
Selects all elements of this collection which do not satisfy a predicate.
Value parameters
pred
the predicate used to test elements.
Attributes
Returns
a new collection consisting of all elements of this collection that do not satisfy the given predicate pred. Their order may not be preserved.
Source
Builds a new collection by applying a function to all elements of this collection and using the elements of the resulting collections.
Builds a new collection by applying a function to all elements of this collection and using the elements of the resulting collections.
For example:
def getWords(lines: Seq[String]): Seq[String] = lines flatMap (line => line split "\\W+")
The type of the resulting collection is guided by the static type of collection. This might cause unexpected results sometimes. For example:
// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set
def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet)
// lettersOf will return a Set[Char], not a Seq
def lettersOf(words: Seq[String]) = words.toSet flatMap ((word: String) => word.toSeq)
// xs will be an Iterable[Int]
val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2)
// ys will be a Map[Int, Int]
val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)
Type parameters
B
the element type of the returned collection.
Value parameters
f
the function to apply to each element.
Attributes
Returns
a new collection resulting from applying the given collection-valued function f to each element of this collection and concatenating the results.
Source
Converts this collection of iterable collections into a collection formed by the elements of these iterable collections.
Converts this collection of iterable collections into a collection formed by the elements of these iterable collections.
The resulting collection's type will be guided by the type of collection. For example:
val xs = List(
Set(1, 2, 3),
Set(1, 2, 3)
).flatten
// xs == List(1, 2, 3, 1, 2, 3)
val ys = Set(
List(1, 2, 3),
List(3, 2, 1)
).flatten
// ys == Set(1, 2, 3)
Type parameters
B
the type of the elements of each iterable collection.
Value parameters
asIterable
an implicit conversion which asserts that the element type of this collection is an Iterable.
Attributes
Returns
a new collection resulting from concatenating all element collections.
Source
Builds a new collection by applying a function to all elements of this collection.
Builds a new collection by applying a function to all elements of this collection.
Type parameters
B
the element type of the returned collection.
Value parameters
f
the function to apply to each element.
Attributes
Returns
a new collection resulting from applying the given function f to each element of this collection and collecting the results.
Source
Produces a collection containing cumulative results of applying the operator going left to right, including the initial value.
Produces a collection containing cumulative results of applying the operator going left to right, including the initial value.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Type parameters
B
the type of the elements in the resulting collection
Value parameters
op
the binary operator applied to the intermediate result and the element
z
the initial value
Attributes
Returns
collection with intermediate results
Source
Selects an interval of elements.
Selects an interval of elements. The returned collection is made up of all elements x which satisfy the invariant:
from <= indexOf(x) < until
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
from
the lowest index to include from this collection.
until
the lowest index to EXCLUDE from this collection.
Attributes
Returns
a collection containing the elements greater than or equal to index from extending up to (but not including) index until of this collection.
Source
Splits this collection into a prefix/suffix pair according to a predicate.
Splits this collection into a prefix/suffix pair according to a predicate.
Note: c span p is equivalent to (but possibly more efficient than) (c takeWhile p, c dropWhile p), provided the evaluation of the predicate p does not cause any side-effects.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
p
the test predicate
Attributes
Returns
a pair consisting of the longest prefix of this collection whose elements all satisfy p, and the rest of this collection.
Source
Selects the first n elements.
Selects the first n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
n
the number of elements to take from this collection.
Attributes
Returns
a collection consisting only of the first n elements of this collection, or else the whole collection, if it has less than n elements. If n is negative, returns an empty collection.
Source
Selects the longest prefix of elements that satisfy a predicate.
Selects the longest prefix of elements that satisfy a predicate.
The matching prefix starts with the first element of this collection, and the element following the prefix is the first element that does not satisfy the predicate. The matching prefix may empty, so that this method returns an empty collection.
Example:
scala> List(1, 2, 3, 100, 4).takeWhile(n => n < 10)
val res0: List[Int] = List(1, 2, 3)
scala> List(1, 2, 3, 100, 4).takeWhile(n => n == 0)
val res1: List[Int] = List()
Use span to obtain both the prefix and suffix. Use filter to retain only those elements from the entire collection that satisfy the predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
p
The predicate used to test elements.
Attributes
Returns
the longest prefix of this collection whose elements all satisfy the predicate p.
Source
Applies a side-effecting function to each element in this collection.
Applies a side-effecting function to each element in this collection. Strict collections will apply f to their elements immediately, while lazy collections like Views and LazyLists will only apply f on each element if and when that element is evaluated, and each time that element is evaluated.
Type parameters
U
the return type of f
Value parameters
f
a function to apply to each element in this collection
Attributes
Returns
The same logical collection as this
Source
Zips this collection with its indices.
Zips this collection with its indices.
Attributes
Returns
A new collection containing pairs consisting of all elements of this collection paired with their index. Indices start at 0.
Example
List("a", "b", "c").zipWithIndex == List(("a", 0), ("b", 1), ("c", 2))
Source
Appends all elements of this collection to a string builder using start, end, and separator strings.
Appends all elements of this collection to a string builder using start, end, and separator strings. The written text begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.
Example:
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)
scala> val b = new StringBuilder()
b: StringBuilder =
scala> a.addString(b , "List(" , ", " , ")")
res5: StringBuilder = List(1, 2, 3, 4)
Value parameters
b
the string builder to which elements are appended.
end
the ending string.
sep
the separator string.
start
the starting string.
Attributes
Returns
the string builder b to which elements were appended.
Source
Appends all elements of this collection to a string builder using a separator string.
Appends all elements of this collection to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection, separated by the string sep.
Example:
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)
scala> val b = new StringBuilder()
b: StringBuilder =
scala> a.addString(b, ", ")
res0: StringBuilder = 1, 2, 3, 4
Value parameters
b
the string builder to which elements are appended.
sep
the separator string.
Attributes
Returns
the string builder b to which elements were appended.
Source
Appends all elements of this collection to a string builder.
Appends all elements of this collection to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection without any separator string.
Example:
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)
scala> val b = new StringBuilder()
b: StringBuilder =
scala> val h = a.addString(b)
h: StringBuilder = 1234
Value parameters
b
the string builder to which elements are appended.
Attributes
Returns
the string builder b to which elements were appended.
Source
Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.
Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
pf
the partial function
Attributes
Returns
an option value containing pf applied to the first value for which it is defined, or None if none exists.
Example
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
Source
Copies elements to an array, returning the number of elements written.
Copies elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.
Type parameters
B
the type of the elements of the array.
Value parameters
xs
the array to fill.
Attributes
Returns
the number of elements written to the array
Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
Source
Copies elements to an array, returning the number of elements written.
Copies elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.
Type parameters
B
the type of the elements of the array.
Value parameters
start
the starting index of xs.
xs
the array to fill.
Attributes
Returns
the number of elements written to the array
Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
Source
Copy elements to an array, returning the number of elements written.
Copy elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with at most len elements of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached, or len elements have been copied.
Type parameters
B
the type of the elements of the array.
Value parameters
len
the maximal number of elements to copy.
start
the starting index of xs.
xs
the array to fill.
Attributes
Returns
the number of elements written to the array
Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
Source
Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
Note: will not terminate for infinite-sized collections.
Type parameters
B
the type of the elements of that
Value parameters
p
the test predicate, which relates elements from both collections
that
the other collection
Attributes
Returns
true if both collections have the same length and p(x, y) is true for all corresponding elements x of this iterator and y of that, otherwise false
Source
Counts the number of elements in the collection which satisfy a predicate.
Counts the number of elements in the collection which satisfy a predicate.
Note: will not terminate for infinite-sized collections.
Value parameters
p
the predicate used to test elements.
Attributes
Returns
the number of elements satisfying the predicate p.
Source
Tests whether a predicate holds for at least one element of this collection.
Tests whether a predicate holds for at least one element of this collection.
Note: may not terminate for infinite-sized collections.
Value parameters
p
the predicate used to test elements.
Attributes
Returns
true if the given predicate p is satisfied by at least one element of this collection, otherwise false
Source
Finds the first element of the collection satisfying a predicate, if any.
Finds the first element of the collection satisfying a predicate, if any.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
p
the predicate used to test elements.
Attributes
Returns
an option value containing the first element in the collection that satisfies p, or None if none exists.
Source
Applies the given binary operator op to the given initial value z and all elements of this collection.
Applies the given binary operator op to the given initial value z and all elements of this collection.
For each application of the operator, each operand is either an element of this collection, the initial value, or another such application of the operator.
The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation. The initial value may be used an arbitrary number of times, but at least once.
If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.
Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative. In either case, it is also necessary that the initial value be a neutral value for the operator, e.g. Nil for List concatenation or 1 for multiplication.
The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.
Note: will not terminate for infinite-sized collections.
Type parameters
A1
The type parameter for the binary operator, a supertype of A.
Value parameters
op
A binary operator; must be associative for the result to always be the same across runs.
z
An initial value; may be used an arbitrary number of times in the computation of the result; must be a neutral value for op for the result to always be the same across runs.
Attributes
Returns
The result of applying op between all the elements and z, or z if this collection is empty.
Source
Applies the given binary operator op to the given initial value z and all elements of this collection, going left to right.
Applies the given binary operator op to the given initial value z and all elements of this collection, going left to right. Returns the initial value if this collection is empty.
"Going left to right" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op( op( ... op( op(z, x1), x2) ... ), xn).
If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the initial value, and each other left operand is itself an application of the operator. The elements of this collection and the initial value all appear exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the binary operator.
Value parameters
op
A binary operator.
z
An initial value.
Attributes
Returns
The result of applying op to z and all elements of this collection, going left to right. Returns z if this collection is empty.
Source
Applies the given binary operator op to all elements of this collection and the given initial value z, going right to left.
Applies the given binary operator op to all elements of this collection and the given initial value z, going right to left. Returns the initial value if this collection is empty.
"Going right to left" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op(x1, op(x2, op( ... op(xn, z) ... ))).
If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the initial value, and each other right operand is itself an application of the operator. The elements of this collection and the initial value all appear exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the binary operator.
Value parameters
op
A binary operator.
z
An initial value.
Attributes
Returns
The result of applying op to all elements of this collection and z, going right to left. Returns z if this collection is empty.
Source
Tests whether a predicate holds for all elements of this collection.
Tests whether a predicate holds for all elements of this collection.
Note: may not terminate for infinite-sized collections.
Value parameters
p
the predicate used to test elements.
Attributes
Returns
true if this collection is empty or the given predicate p holds for all elements of this collection, otherwise false.
Source
Applies f to each element for its side effects.
Applies f to each element for its side effects. Note: U parameter needed to help scalac's type inference.
Attributes
Source
Tests whether the collection is empty.
Tests whether the collection is empty.
Note: The default implementation creates and discards an iterator.
Note: Implementations in subclasses that are not repeatedly iterable must take care not to consume any elements when isEmpty is called.
Attributes
Returns
true if the collection contains no elements, false otherwise.
Source
Tests whether this collection can be repeatedly traversed.
Tests whether this collection can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.
Attributes
Returns
true if it is repeatedly traversable, false otherwise.
Source
Finds the largest element.
Finds the largest element.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The type over which the ordering is defined.
Value parameters
ord
An ordering to be used for comparing elements.
Attributes
Returns
the largest element of this collection with respect to the ordering ord.
Throws
Source
Finds the first element which yields the largest value measured by function f.
Finds the first element which yields the largest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the function f.
Value parameters
cmp
An ordering to be used for comparing elements.
f
The measuring function.
Attributes
Returns
the first element of this collection with the largest value measured by function f with respect to the ordering cmp.
Throws
Source
Finds the first element which yields the largest value measured by function f.
Finds the first element which yields the largest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the function f.
Value parameters
cmp
An ordering to be used for comparing elements.
f
The measuring function.
Attributes
Returns
an option value containing the first element of this collection with the largest value measured by function f with respect to the ordering cmp.
Source
Finds the largest element.
Finds the largest element.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The type over which the ordering is defined.
Value parameters
ord
An ordering to be used for comparing elements.
Attributes
Returns
an option value containing the largest element of this collection with respect to the ordering ord.
Source
Finds the smallest element.
Finds the smallest element.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The type over which the ordering is defined.
Value parameters
ord
An ordering to be used for comparing elements.
Attributes
Returns
the smallest element of this collection with respect to the ordering ord.
Throws
Source
Finds the first element which yields the smallest value measured by function f.
Finds the first element which yields the smallest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the function f.
Value parameters
cmp
An ordering to be used for comparing elements.
f
The measuring function.
Attributes
Returns
the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.
Throws
Source
Finds the first element which yields the smallest value measured by function f.
Finds the first element which yields the smallest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the function f.
Value parameters
cmp
An ordering to be used for comparing elements.
f
The measuring function.
Attributes
Returns
an option value containing the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.
Source
Finds the smallest element.
Finds the smallest element.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The type over which the ordering is defined.
Value parameters
ord
An ordering to be used for comparing elements.
Attributes
Returns
an option value containing the smallest element of this collection with respect to the ordering ord.
Source
Displays all elements of this collection in a string using start, end, and separator strings.
Displays all elements of this collection in a string using start, end, and separator strings.
Delegates to addString, which can be overridden.
Value parameters
end
the ending string.
sep
the separator string.
start
the starting string.
Attributes
Returns
a string representation of this collection. The resulting string begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.
Example
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Source
Displays all elements of this collection in a string using a separator string.
Displays all elements of this collection in a string using a separator string.
Delegates to addString, which can be overridden.
Value parameters
sep
the separator string.
Attributes
Returns
a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.
Example
List(1, 2, 3).mkString("|") = "1|2|3"
Source
Displays all elements of this collection in a string.
Displays all elements of this collection in a string.
Delegates to addString, which can be overridden.
Attributes
Returns
a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection follow each other without any separator string.
Source
Tests whether the collection is not empty.
Tests whether the collection is not empty.
Attributes
Returns
true if the collection contains at least one element, false otherwise.
Source
Multiplies together the elements of this collection.
Multiplies together the elements of this collection.
The default implementation uses reduce for a known non-empty collection, foldLeft otherwise.
Note: will not terminate for infinite-sized collections.
Type parameters
B
the result type of the * operator.
Value parameters
num
an implicit parameter defining a set of numeric operations which includes the * operator to be used in forming the product.
Attributes
Returns
the product of all elements of this collection with respect to the * operator in num.
Source
Applies the given binary operator op to all elements of this collection.
Applies the given binary operator op to all elements of this collection.
For each application of the operator, each operand is either an element of this collection or another such application of the operator. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.
If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.
Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The type parameter for the binary operator, a supertype of A.
Value parameters
op
A binary operator; must be associative for the result to always be the same across runs.
Attributes
Returns
The result of applying op between all the elements if the collection is nonempty.
Throws
Source
Applies the given binary operator op to all elements of this collection, going left to right.
Applies the given binary operator op to all elements of this collection, going left to right.
"Going left to right" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op( op( op( ... op(x1, x2) ... ), xn-1), xn).
If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the first element of this collection and each other left operand is itself an application of the operator. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the binary operator, a supertype of A.
Value parameters
op
A binary operator.
Attributes
Returns
The result of applying op to all elements of this collection, going left to right.
Throws
Source
If this collection is nonempty, reduces it with the given binary operator op, going left to right.
If this collection is nonempty, reduces it with the given binary operator op, going left to right.
The behavior is the same as reduceLeft except that the value is None if the collection is empty. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the binary operator, a supertype of A.
Value parameters
op
A binary operator.
Attributes
Returns
The result of reducing this collection with op going left to right if the collection is nonempty, inside a Some, and None otherwise.
Source
If this collection is nonempty, reduces it with the given binary operator op.
If this collection is nonempty, reduces it with the given binary operator op.
The behavior is the same as reduce except that the value is None if the collection is empty. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parameters
B
A type parameter for the binary operator, a supertype of A.
Value parameters
op
A binary operator; must be associative for the result to always be the same across runs.
Attributes
Returns
The result of reducing this collection with op if the collection is nonempty, inside a Some, and None otherwise.
Source
Applies the given binary operator op to all elements of this collection, going right to left.
Applies the given binary operator op to all elements of this collection, going right to left.
"Going right to left" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op(x1, op(x2, op( ... op(xn-1, xn) ... ))).
If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the last element of this collection and each other right operand is itself an application of the operator. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the binary operator, a supertype of A.
Value parameters
op
A binary operator.
Attributes
Returns
The result of applying op to all elements of this collection, going right to left.
Throws
Source
If this collection is nonempty, reduces it with the given binary operator op, going right to left.
If this collection is nonempty, reduces it with the given binary operator op, going right to left.
The behavior is the same as reduceRight except that the value is None if the collection is empty. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the binary operator, a supertype of A.
Value parameters
op
A binary operator.
Attributes
Returns
The result of reducing this collection with op going right to left if the collection is nonempty, inside a Some, and None otherwise.
Source
The size of this collection.
The size of this collection.
Note: will not terminate for infinite-sized collections.
Attributes
Returns
the number of elements in this collection.
Source
Splits this collection into a prefix/suffix pair at a given position.
Splits this collection into a prefix/suffix pair at a given position.
Note: c splitAt n is equivalent to (but possibly more efficient than) (c take n, c drop n).
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
n
the position at which to split.
Attributes
Returns
a pair of collections consisting of the first n elements of this collection, and the other elements.
Source
Sums the elements of this collection.
Sums the elements of this collection.
The default implementation uses reduce for a known non-empty collection, foldLeft otherwise.
Note: will not terminate for infinite-sized collections.
Type parameters
B
the result type of the + operator.
Value parameters
num
an implicit parameter defining a set of numeric operations which includes the + operator to be used in forming the sum.
Attributes
Returns
the sum of all elements of this collection with respect to the + operator in num.
Source
Given a collection factory factory, converts this collection to the appropriate representation for the current element type A.
Given a collection factory factory, converts this collection to the appropriate representation for the current element type A. Example uses:
xs.to(List)
xs.to(ArrayBuffer)
xs.to(BitSet) // for xs: Iterable[Int]
Attributes
Source
Converts this collection to an Array.
Converts this collection to an Array.
Implementation note: DO NOT call Array.from from this method.
Type parameters
B
The type of elements of the result, a supertype of A.
Attributes
Returns
This collection as an Array[B].
Source
Converts this collection to a Buffer.
Converts this collection to a Buffer.
Type parameters
B
The type of elements of the result, a supertype of A.
Attributes
Returns
This collection as a Buffer[B].
Source
Converts this collection to an IndexedSeq.
Converts this collection to an IndexedSeq.
Attributes
Returns
This collection as an IndexedSeq[A].
Source
Converts this collection to a List.
Converts this collection to a List.
Attributes
Returns
This collection as a List[A].
Source
Converts this collection to a Map, given an implicit coercion from the collection's type to a key-value tuple.
Converts this collection to a Map, given an implicit coercion from the collection's type to a key-value tuple.
Type parameters
K
The key type for the resulting map.
V
The value type for the resulting map.
Value parameters
ev
An implicit coercion from A to [K, V].
Attributes
Returns
This collection as a Map[K, V].
Source
Attributes
Returns
This collection as a Seq[A]. This is equivalent to to(Seq) but might be faster.
Source
Converts this collection to a Set.
Converts this collection to a Set.
Type parameters
B
The type of elements of the result, a supertype of A.
Attributes
Returns
This collection as a Set[B].
Source
Converts this collection to a Vector.
Converts this collection to a Vector.
Attributes
Returns
This collection as a Vector[A].
Source
Attributes
Deprecated
[Since version 2.13.0] Use foldLeft instead of /:
Source
Attributes
Deprecated
[Since version 2.13.0] Use foldRight instead of :\\
Source
Aggregates the results of applying an operator to subsequent elements.
Aggregates the results of applying an operator to subsequent elements.
Since this method degenerates to foldLeft for sequential (non-parallel) collections, where the combining operation is ignored, it is advisable to prefer foldLeft for that case.
For parallel collections, use the aggregate method specified by scala.collection.parallel.ParIterableLike.
Type parameters
B
the result type, produced by seqop, combop, and by this function as a final result.
Value parameters
combop
an associative operator for combining sequential results, unused for sequential collections.
seqop
the binary operator used to accumulate the result.
z
the start value, a neutral element for seqop.
Attributes
Deprecated
[Since version 2.13.0] For sequential collections, prefer `foldLeft(z)(seqop)`. For parallel collections, use `ParIterableLike#aggregate`.
Source
Attributes
Deprecated
[Since version 2.13.0] Use `dest ++= coll` instead
Source
Tests whether this collection is known to have a finite size.
Tests whether this collection is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as Stream, the predicate returns **true** if all elements have been computed. It returns **false** if the stream is not yet evaluated to the end. Non-empty Iterators usually return **false** even if they were created from a collection with a known finite size.
Note: many collection methods will not work on collections of infinite sizes. The typical failure mode is an infinite loop. These methods always attempt a traversal without checking first that hasDefiniteSize returns **true**. However, checking hasDefiniteSize can provide an assurance that size is well-defined and non-termination is not a concern.
Attributes
Returns
**true** if this collection is known to have finite size, **false** otherwise.
See also
method knownSize for a more useful alternative
Deprecated
[Since version 2.13.0] Check .knownSize instead of .hasDefiniteSize for more actionable information (see scaladoc for details)
This method is deprecated in 2.13 because it does not provide any actionable information. As noted above, even the collection library itself does not use it. When there is no guarantee that a collection is finite, it is generally best to attempt a computation anyway and document that it will not terminate for infinite collections rather than backing out because this would prevent performing the computation on collections that are in fact finite even though hasDefiniteSize returns false.
Source
Attributes
Deprecated
[Since version 2.13.0] Use .iterator instead of .toIterator
Source
Attributes
Deprecated
[Since version 2.13.0] Use .to(LazyList) instead of .toStream
Source