ParIterableLike - Scala Standard Library 2.11.6 - scala.collection.parallel.ParIterableLike
Keywords: ParIterableLike Scala Standard Library 2.11.6 scala.collection.parallel.ParIterableLike

scala.collection.parallel

# ParIterableLike

###
Related Doc: package parallel

#### trait ParIterableLike[+T, +Repr <: ParIterable[T], +Sequential <: scala.Iterable[T] with IterableLike[T, Sequential]] extends GenIterableLike[T, Repr] with CustomParallelizable[T, Repr] with Parallel with HasNewCombiner[T, Repr]

A template trait for parallel collections of type `ParIterable[T]`.

This is a base trait for Scala parallel collections. It defines behaviour common to all parallel collections. Concrete parallel collections should inherit this trait and `ParIterable` if they want to define specific combiner factories.

Parallel operations are implemented with divide and conquer style algorithms that parallelize well. The basic idea is to split the collection into smaller parts until they are small enough to be operated on sequentially.

All of the parallel operations are implemented as tasks within this trait. Tasks rely on the concept of splitters, which extend iterators. Every parallel collection defines:

    def splitter: IterableSplitter[T]

which returns an instance of `IterableSplitter[T]`, which is a subtype of `Splitter[T]`. Splitters have a method `remaining` to check the remaining number of elements, and method `split` which is defined by splitters. Method `split` divides the splitters iterate over into disjunct subsets:

    def split: Seq[Splitter]

which splits the splitter into a sequence of disjunct subsplitters. This is typically a very fast operation which simply creates wrappers around the receiver collection. This can be repeated recursively.

Tasks are scheduled for execution through a scala.collection.parallel.TaskSupport object, which can be changed through the `tasksupport` setter of the collection.

Method `newCombiner` produces a new combiner. Combiners are an extension of builders. They provide a method `combine` which combines two combiners and returns a combiner containing elements of both combiners. This method can be implemented by aggressively copying all the elements into the new combiner or by lazily binding their results. It is recommended to avoid copying all of the elements for performance reasons, although that cost might be negligible depending on the use case. Standard parallel collection combiners avoid copying when merging results, relying either on a two-step lazy construction or specific data-structure properties.

Methods:

    def seq: Sequential
    def par: Repr

produce the sequential or parallel implementation of the collection, respectively. Method `par` just returns a reference to this parallel collection. Method `seq` is efficient - it will not copy the elements. Instead, it will create a sequential version of the collection using the same underlying data structure. Note that this is not the case for sequential collections in general - they may copy the elements and produce a different underlying data structure.

The combination of methods `toMap`, `toSeq` or `toSet` along with `par` and `seq` is a flexible way to change between different collection types.

Since this trait extends the `GenIterable` trait, methods like `size` must also be implemented in concrete collections, while `iterator` forwards to `splitter` by default.

Each parallel collection is bound to a specific fork/join pool, on which dormant worker threads are kept. The fork/join pool contains other information such as the parallelism level, that is, the number of processors used. When a collection is created, it is assigned the default fork/join pool found in the `scala.parallel` package object.

Parallel collections are not necessarily ordered in terms of the `foreach` operation (see `Traversable`). Parallel sequences have a well defined order for iterators - creating an iterator and traversing the elements linearly will always yield the same order. However, bulk operations such as `foreach`, `map` or `filter` always occur in undefined orders for all parallel collections.

Existing parallel collection implementations provide strict parallel iterators. Strict parallel iterators are aware of the number of elements they have yet to traverse. It's also possible to provide non-strict parallel iterators, which do not know the number of elements remaining. To do this, the new collection implementation must override `isStrictSplitterCollection` to `false`. This will make some operations unavailable.

To create a new parallel collection, extend the `ParIterable` trait, and implement `size`, `splitter`, `newCombiner` and `seq`. Having an implicit combiner factory requires extending this trait in addition, as well as providing a companion object, as with regular collections.

Method `size` is implemented as a constant time operation for parallel collections, and parallel collection operations rely on this assumption.

The higher-order functions passed to certain operations may contain side-effects. Since implementations of bulk operations may not be sequential, this means that side-effects may not be predictable and may produce data-races, deadlocks or invalidation of state if care is not taken. It is up to the programmer to either avoid using side-effects or to use some form of synchronization when accessing mutable data.

T

  the element type of the collection

Repr

  the type of the actual collection containing the elements

Self Type
  ParIterableLike[T, Repr, Sequential]
Source
  ParIterableLike.scala

Linear Supertypes
HasNewCombiner[T, Repr], Parallel, CustomParallelizable[T, Repr], GenIterableLike[T, Repr], GenTraversableLike[T, Repr], Parallelizable[T, Repr], GenTraversableOnce[T], AnyRef, Any
Known Subclasses
DefaultKeySet, DefaultValuesIterable, ParArray, ParHashMap, ParHashMap, ParHashSet, ParHashSet, ParIterable, ParIterable, ParIterable, ParMap, ParMap, ParMap, ParMapLike, ParMapLike, ParRange, ParSeq, ParSeq, ParSeq, ParSeqLike, ParSet, ParSet, ParSet, ParSetLike, ParSetLike, ParTrieMap, ParVector, WithDefault, WithDefault, WithDefault
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Inherited

1. ParIterableLike
2. HasNewCombiner
3. Parallel
4. CustomParallelizable
5. GenIterableLike
6. GenTraversableLike
7. Parallelizable
8. GenTraversableOnce
9. AnyRef
10. Any

Implicitly

1. by CollectionsHaveToParArray
2. by any2stringadd
3. by StringFormat
4. by Ensuring
5. by ArrowAssoc

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1. Public
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### Type Members

1. #### trait Accessor[R, Tp] extends StrictSplitterCheckTask[R, Tp]

   Standard accessor task that iterates over the elements of the collection.

   Standard accessor task that iterates over the elements of the collection.

   R

     type of the result of this method (`R` for result).

   Tp

     the representation type of the task at hand.

   Attributes
     protected

2. #### class Aggregate[S] extends Accessor[S, Aggregate[S]]

   Attributes
     protected[this]

3. #### trait BuilderOps[Elem, To] extends AnyRef

4. #### class Collect[S, That] extends Transformer[Combiner[S, That], Collect[S, That]]

   Attributes
     protected[this]

5. #### abstract class Composite[FR, SR, R, First <: StrictSplitterCheckTask[FR, _], Second <: StrictSplitterCheckTask[SR, _]] extends NonDivisibleTask[R, Composite[FR, SR, R, First, Second]]

   Attributes
     protected[this]

6. #### class Copy[U >: T, That] extends Transformer[Combiner[U, That], Copy[U, That]]

   Attributes
     protected

7. #### class CopyToArray[U >: T, This >: Repr] extends Accessor[Unit, CopyToArray[U, This]]

   Attributes
     protected[this]

8. #### class Count extends Accessor[Int, Count]

   Attributes
     protected[this]

9. #### class CreateScanTree[U >: T] extends Transformer[ScanTree[U], CreateScanTree[U]]

   Attributes
     protected[this]

10. #### class Drop[U >: T, This >: Repr] extends Transformer[Combiner[U, This], Drop[U, This]]

    Attributes
      protected[this]

11. #### class Exists extends Accessor[Boolean, Exists]

    Attributes
      protected[this]

12. #### class Filter[U >: T, This >: Repr] extends Transformer[Combiner[U, This], Filter[U, This]]

    Attributes
      protected[this]

13. #### class FilterNot[U >: T, This >: Repr] extends Transformer[Combiner[U, This], FilterNot[U, This]]

    Attributes
      protected[this]

14. #### class Find[U >: T] extends Accessor[Option[U], Find[U]]

    Attributes
      protected[this]

15. #### class FlatMap[S, That] extends Transformer[Combiner[S, That], FlatMap[S, That]]

    Attributes
      protected[this]

16. #### class Fold[U >: T] extends Accessor[U, Fold[U]]

    Attributes
      protected[this]

17. #### class Forall extends Accessor[Boolean, Forall]

    Attributes
      protected[this]

18. #### class Foreach[S] extends Accessor[Unit, Foreach[S]]

    Attributes
      protected[this]

19. #### class FromScanTree[U >: T, That] extends StrictSplitterCheckTask[Combiner[U, That], FromScanTree[U, That]]

    Attributes
      protected[this]

20. #### class GroupBy[K, U >: T] extends Transformer[HashMapCombiner[K, U], GroupBy[K, U]]

    Attributes
      protected[this]

21. #### class Map[S, That] extends Transformer[Combiner[S, That], Map[S, That]]

    Attributes
      protected[this]

22. #### class Max[U >: T] extends Accessor[Option[U], Max[U]]

    Attributes
      protected[this]

23. #### class Min[U >: T] extends Accessor[Option[U], Min[U]]

    Attributes
      protected[this]

24. #### trait NonDivisible[R] extends NonDivisibleTask[R, NonDivisible[R]]

    Attributes
      protected[this]

25. #### trait NonDivisibleTask[R, Tp] extends StrictSplitterCheckTask[R, Tp]

    Attributes
      protected[this]

26. #### abstract class ParComposite[FR, SR, R, First <: StrictSplitterCheckTask[FR, _], Second <: StrictSplitterCheckTask[SR, _]] extends Composite[FR, SR, R, First, Second]

    Performs two tasks in parallel, and waits for both to finish.

    Performs two tasks in parallel, and waits for both to finish.

    Attributes
      protected[this]

27. #### class Partition[U >: T, This >: Repr] extends Transformer[(Combiner[U, This], Combiner[U, This]), Partition[U, This]]

    Attributes
      protected[this]

28. #### class Product[U >: T] extends Accessor[U, Product[U]]

    Attributes
      protected[this]

29. #### class Reduce[U >: T] extends Accessor[Option[U], Reduce[U]]

    Attributes
      protected[this]

30. #### abstract class ResultMapping[R, Tp, R1] extends NonDivisibleTask[R1, ResultMapping[R, Tp, R1]]

    Attributes
      protected[this]

31. #### type SSCTask[R, Tp] = StrictSplitterCheckTask[R, Tp]

32. #### case class ScanLeaf[U >: T](pit: IterableSplitter[U], op: (U, U) ⇒ U, from: Int, len: Int, prev: Option[ScanLeaf[U]], acc: U) extends ScanTree[U] with scala.Product with Serializable

    Attributes
      protected[this]

33. #### case class ScanNode[U >: T](left: ScanTree[U], right: ScanTree[U]) extends ScanTree[U] with scala.Product with Serializable

    Attributes
      protected[this]

34. #### trait ScanTree[U >: T] extends AnyRef

    Attributes
      protected[this]

35. #### abstract class SeqComposite[FR, SR, R, First <: StrictSplitterCheckTask[FR, _], Second <: StrictSplitterCheckTask[SR, _]] extends Composite[FR, SR, R, First, Second]

    Sequentially performs one task after another.

    Sequentially performs one task after another.

    Attributes
      protected[this]

36. #### trait SignallingOps[PI <: DelegatedSignalling] extends AnyRef

37. #### class Slice[U >: T, This >: Repr] extends Transformer[Combiner[U, This], Slice[U, This]]

    Attributes
      protected[this]

38. #### class Span[U >: T, This >: Repr] extends Transformer[(Combiner[U, This], Combiner[U, This]), Span[U, This]]

    Attributes
      protected[this]

39. #### class SplitAt[U >: T, This >: Repr] extends Transformer[(Combiner[U, This], Combiner[U, This]), SplitAt[U, This]]

    Attributes
      protected[this]

40. #### trait StrictSplitterCheckTask[R, Tp] extends Task[R, Tp]

    Attributes
      protected

41. #### class Sum[U >: T] extends Accessor[U, Sum[U]]

    Attributes
      protected[this]

42. #### class Take[U >: T, This >: Repr] extends Transformer[Combiner[U, This], Take[U, This]]

    Attributes
      protected[this]

43. #### class TakeWhile[U >: T, This >: Repr] extends Transformer[(Combiner[U, This], Boolean), TakeWhile[U, This]]

    Attributes
      protected[this]

44. #### trait TaskOps[R, Tp] extends AnyRef

45. #### class ToParCollection[U >: T, That] extends Transformer[Combiner[U, That], ToParCollection[U, That]]

    Attributes
      protected[this]

46. #### class ToParMap[K, V, That] extends Transformer[Combiner[(K, V), That], ToParMap[K, V, That]]

    Attributes
      protected[this]

47. #### trait Transformer[R, Tp] extends Accessor[R, Tp]

    Attributes
      protected

48. #### class Zip[U >: T, S, That] extends Transformer[Combiner[(U, S), That], Zip[U, S, That]]

    Attributes
      protected[this]

49. #### class ZipAll[U >: T, S, That] extends Transformer[Combiner[(U, S), That], ZipAll[U, S, That]]

    Attributes
      protected[this]

### Abstract Value Members

1. #### abstract def newCombiner: Combiner[T, Repr]

   Attributes
     protected[this]
   Definition Classes
     HasNewCombiner

2. #### abstract def seq: Sequential

   Definition Classes
     ParIterableLike → Parallelizable → GenTraversableOnce

3. #### abstract def size: Int

   The size of this general collection.

   The size of this general collection.

   Note: will not terminate for infinite-sized collections.

   returns

     the number of elements in this general collection.

   Definition Classes
     GenTraversableLike → GenTraversableOnce

4. #### abstract def splitter: IterableSplitter[T]

   Creates a new parallel iterator used to traverse the elements of this parallel collection.

   Creates a new parallel iterator used to traverse the elements of this parallel collection. This iterator is more specific than the iterator of the returned by `iterator`, and augmented with additional accessor and transformer methods.

   returns

     a parallel iterator

   Attributes
     protected[scala.collection.parallel]

5. #### abstract def stringPrefix: String

   Defines the prefix of this object's `toString` representation.

   Defines the prefix of this object's `toString` representation.

   returns

     a string representation which starts the result of `toString` applied to this general collection. By default the string prefix is the simple name of the collection class general collection.

   Definition Classes
     GenTraversableLike

### Concrete Value Members

1. #### final def !=(arg0: Any): Boolean

   Test two objects for inequality.

   Test two objects for inequality.

   returns

     `true` if !(this == that), false otherwise.

   Definition Classes
     AnyRef → Any

2. #### final def ##(): Int

   Equivalent to `x.hashCode` except for boxed numeric types and `null`.

   Equivalent to `x.hashCode` except for boxed numeric types and `null`. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For `null` returns a hashcode where `null.hashCode` throws a `NullPointerException`.

   returns

     a hash value consistent with ==

   Definition Classes
     AnyRef → Any

3. #### def +(other: String): String

   Implicit information
     This member is added by an implicit conversion from ParIterableLike[T, Repr, Sequential] to any2stringadd[ParIterableLike[T, Repr, Sequential]] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd

4. #### def ++[B](that: GenTraversableOnce[B]): ParIterable[B]

   [use case] Returns a new parallel iterable containing the elements from the left hand operand followed by the elements from the right hand operand.

   [use case]

   Returns a new parallel iterable containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the parallel iterable is the most specific superclass encompassing the element types of the two operands.

   Example:

       scala> val a = List(1)
       a: List[Int] = List(1)

       scala> val b = List(2)
       b: List[Int] = List(2)

       scala> val c = a ++ b
       c: List[Int] = List(1, 2)

       scala> val d = List('a')
       d: List[Char] = List(a)

       scala> val e = c ++ d
       e: List[AnyVal] = List(1, 2, a)

   B

     the element type of the returned collection.

   that

     the traversable to append.

   returns

     a new parallel iterable which contains all elements of this parallel iterable followed by all elements of `that`.

   Definition Classes
     ParIterableLike → GenTraversableLike
   Full Signature

   #### def ++[U >: T, That](that: GenTraversableOnce[U])(implicit bf: CanBuildFrom[Repr, U, That]): That

5. #### def ->[B](y: B): (ParIterableLike[T, Repr, Sequential], B)

   Implicit information
     This member is added by an implicit conversion from ParIterableLike[T, Repr, Sequential] to ArrowAssoc[ParIterableLike[T, Repr, Sequential]] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()

6. #### def /:[S](z: S)(op: (S, T) ⇒ S): S

   Applies a binary operator to a start value and all elements of this parallel iterable, going left to right.

   Applies a binary operator to a start value and all elements of this parallel iterable, going left to right.

   Note: `/:` is alternate syntax for `foldLeft`; `z /: xs` is the same as `xs foldLeft z`.

   Examples:

   Note that the folding function used to compute b is equivalent to that used to compute c.

       scala> val a = List(1,2,3,4)
       a: List[Int] = List(1, 2, 3, 4)

       scala> val b = (5 /: a)(_+_)
       b: Int = 15

       scala> val c = (5 /: a)((x,y) => x + y)
       c: Int = 15

   Note: will not terminate for infinite-sized collections.

   Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

   z

     the start value.

   op

     the binary operator.

   returns

     the result of inserting `op` between consecutive elements of this parallel iterable, going left to right with the start value `z` on the left:

         op(...op(op(z, x_1), x_2), ..., x_n)

     where `x1, ..., xn` are the elements of this parallel iterable.

   Definition Classes
     ParIterableLike → GenTraversableOnce

7. #### def :\[S](z: S)(op: (T, S) ⇒ S): S

   Applies a binary operator to all elements of this parallel iterable and a start value, going right to left.

   Applies a binary operator to all elements of this parallel iterable and a start value, going right to left.

   Note: `:\` is alternate syntax for `foldRight`; `xs :\ z` is the same as `xs foldRight z`.

   Note: will not terminate for infinite-sized collections.

   Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

   Examples:

   Note that the folding function used to compute b is equivalent to that used to compute c.

       scala> val a = List(1,2,3,4)
       a: List[Int] = List(1, 2, 3, 4)

       scala> val b = (a :\ 5)(_+_)
       b: Int = 15

       scala> val c = (a :\ 5)((x,y) => x + y)
       c: Int = 15

   z

     the start value

   op

     the binary operator

   returns

     the result of inserting `op` between consecutive elements of this parallel iterable, going right to left with the start value `z` on the right:

         op(x_1, op(x_2, ... op(x_n, z)...))

     where `x1, ..., xn` are the elements of this parallel iterable.

   Definition Classes
     ParIterableLike → GenTraversableOnce

8. #### final def ==(arg0: Any): Boolean

   The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

   The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

   arg0

     the object to compare against this object for equality.

   returns

     `true` if the receiver object is equivalent to the argument; `false` otherwise.

   Definition Classes
     AnyRef → Any

9. #### def aggregate[S](z: ⇒ S)(seqop: (S, T) ⇒ S, combop: (S, S) ⇒ S): S

   Aggregates the results of applying an operator to subsequent elements.

   Aggregates the results of applying an operator to subsequent elements.

   This is a more general form of `fold` and `reduce`. It has similar semantics, but does not require the result to be a supertype of the element type. It traverses the elements in different partitions sequentially, using `seqop` to update the result, and then applies `combop` to results from different partitions. The implementation of this operation may operate on an arbitrary number of collection partitions, so `combop` may be invoked arbitrary number of times.

   For example, one might want to process some elements and then produce a `Set`. In this case, `seqop` would process an element and append it to the set, while `combop` would concatenate two sets from different partitions together. The initial value `z` would be an empty set.

       pc.aggregate(Set[Int]())(_ += process(_), _ ++ _)

   Another example is calculating geometric mean from a collection of doubles (one would typically require big doubles for this).

   S

     the type of accumulated results

   z

     the initial value for the accumulated result of the partition - this will typically be the neutral element for the `seqop` operator (e.g. `Nil` for list concatenation or `0` for summation) and may be evaluated more than once

   seqop

     an operator used to accumulate results within a partition

   combop

     an associative operator used to combine results from different partitions

   Definition Classes
     ParIterableLike → GenTraversableOnce

10. #### final def asInstanceOf[T0]: T0

    Cast the receiver object to be of type `T0`.

    Cast the receiver object to be of type `T0`.

    Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression `1.asInstanceOf[String]` will throw a `ClassCastException` at runtime, while the expression `List(1).asInstanceOf[List[String]]` will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

    returns

      the receiver object.

    Definition Classes
      Any
    Exceptions thrown

      `ClassCastException` if the receiver object is not an instance of the erasure of type `T0`.

11. #### def bf2seq[S, That](bf: CanBuildFrom[Repr, S, That]): CanBuildFrom[Sequential, S, That]

    Attributes
      protected[this]

12. #### implicit def builder2ops[Elem, To](cb: Builder[Elem, To]): BuilderOps[Elem, To]

    Attributes
      protected

13. #### def canEqual(other: Any): Boolean

14. #### def clone(): AnyRef

    Create a copy of the receiver object.

    Create a copy of the receiver object.

    The default implementation of the `clone` method is platform dependent.

    returns

      a copy of the receiver object.

    Attributes
      protected[java.lang]
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
    Note

      not specified by SLS as a member of AnyRef

15. #### def collect[B](pf: PartialFunction[A, B]): ParIterable[B]

    [use case] Builds a new collection by applying a partial function to all elements of this parallel iterable on which the function is defined.

    [use case]

    Builds a new collection by applying a partial function to all elements of this parallel iterable on which the function is defined.

    B

      the element type of the returned collection.

    pf

      the partial function which filters and maps the parallel iterable.

    returns

      a new parallel iterable 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.

    Definition Classes
      ParIterableLike → GenTraversableLike
    Full Signature

    #### def collect[S, That](pf: PartialFunction[T, S])(implicit bf: CanBuildFrom[Repr, S, That]): That

16. #### def combinerFactory[S, That](cbf: () ⇒ Combiner[S, That]): CombinerFactory[S, That]

    Attributes
      protected[this]

17. #### def combinerFactory: CombinerFactory[T, Repr]

    Creates a combiner factory.

    Creates a combiner factory. Each combiner factory instance is used once per invocation of a parallel transformer method for a single collection.

    The default combiner factory creates a new combiner every time it is requested, unless the combiner is thread-safe as indicated by its `canBeShared` method. In this case, the method returns a factory which returns the same combiner each time. This is typically done for concurrent parallel collections, the combiners of which allow thread safe access.

    Attributes
      protected[this]

18. #### def copyToArray[U >: T](xs: Array[U], start: Int, len: Int): Unit

    Definition Classes
      ParIterableLike → GenTraversableOnce

19. #### def copyToArray(xs: Array[A], start: Int): Unit

    [use case] Copies values of this parallel iterable to an array.

    [use case]

    Copies values of this parallel iterable to an array. Fills the given array `xs` with values of this parallel iterable, beginning at index `start`. Copying will stop once either the end of the current parallel iterable is reached, or the end of the array is reached.

    Note: will not terminate for infinite-sized collections.

    xs

      the array to fill.

    start

      the starting index.

    Definition Classes
      ParIterableLike → GenTraversableOnce
    Full Signature

    #### def copyToArray[U >: T](xs: Array[U], start: Int): Unit

20. #### def copyToArray(xs: Array[A]): Unit

    [use case] Copies values of this parallel iterable to an array.

    [use case]

    Copies values of this parallel iterable to an array. Fills the given array `xs` with values of this parallel iterable. Copying will stop once either the end of the current parallel iterable is reached, or the end of the array is reached.

    Note: will not terminate for infinite-sized collections.

    xs

      the array to fill.

    Definition Classes
      ParIterableLike → GenTraversableOnce
    Full Signature

    #### def copyToArray[U >: T](xs: Array[U]): Unit

21. #### def count(p: (T) ⇒ Boolean): Int

    Counts the number of elements in the parallel iterable which satisfy a predicate.

    Counts the number of elements in the parallel iterable which satisfy a predicate.

    p

      the predicate used to test elements.

    returns

      the number of elements satisfying the predicate `p`.

    Definition Classes
      ParIterableLike → GenTraversableOnce

22. #### def debugBuffer: ArrayBuffer[String]

23. #### implicit def delegatedSignalling2ops[PI <: DelegatedSignalling](it: PI): SignallingOps[PI]

    Attributes
      protected

24. #### def drop(n: Int): Repr

    Selects all elements except first n ones.

    Selects all elements except first n ones.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    n

      the number of elements to drop from this parallel iterable.

    returns

      a parallel iterable consisting of all elements of this parallel iterable except the first `n` ones, or else the empty parallel iterable, if this parallel iterable has less than `n` elements.

    Definition Classes
      ParIterableLike → GenTraversableLike

25. #### def dropWhile(pred: (T) ⇒ Boolean): Repr

    Drops all elements in the longest prefix of elements that satisfy the predicate, and returns a collection composed of the remaining elements.

    Drops all elements in the longest prefix of elements that satisfy the predicate, and returns a collection composed of the remaining elements.

    This method will use `indexFlag` signalling capabilities. This means that splitters may set and read the `indexFlag` state. The index flag is initially set to maximum integer value.

    pred

      the predicate used to test the elements

    returns

      a collection composed of all the elements after the longest prefix of elements in this parallel iterable that satisfy the predicate `pred`

    Definition Classes
      ParIterableLike → GenTraversableLike

26. #### def ensuring(cond: (ParIterableLike[T, Repr, Sequential]) ⇒ Boolean, msg: ⇒ Any): ParIterableLike[T, Repr, Sequential]

    Implicit information
      This member is added by an implicit conversion from ParIterableLike[T, Repr, Sequential] to Ensuring[ParIterableLike[T, Repr, Sequential]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

27. #### def ensuring(cond: (ParIterableLike[T, Repr, Sequential]) ⇒ Boolean): ParIterableLike[T, Repr, Sequential]

    Implicit information
      This member is added by an implicit conversion from ParIterableLike[T, Repr, Sequential] to Ensuring[ParIterableLike[T, Repr, Sequential]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

28. #### def ensuring(cond: Boolean, msg: ⇒ Any): ParIterableLike[T, Repr, Sequential]

    Implicit information
      This member is added by an implicit conversion from ParIterableLike[T, Repr, Sequential] to Ensuring[ParIterableLike[T, Repr, Sequential]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

29. #### def ensuring(cond: Boolean): ParIterableLike[T, Repr, Sequential]

    Implicit information
      This member is added by an implicit conversion from ParIterableLike[T, Repr, Sequential] to Ensuring[ParIterableLike[T, Repr, Sequential]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

30. #### final def eq(arg0: AnyRef): Boolean

    Tests whether the argument (`arg0`) is a reference to the receiver object (`this`).

    Tests whether the argument (`arg0`) is a reference to the receiver object (`this`).

    The `eq` method implements an equivalence relation on non-null instances of `AnyRef`, and has three additional properties:

    - It is consistent: for any non-null instances `x` and `y` of type `AnyRef`, multiple invocations of `x.eq(y)` consistently returns `true` or consistently returns `false`.
    - For any non-null instance `x` of type `AnyRef`, `x.eq(null)` and `null.eq(x)` returns `false`.
    - `null.eq(null)` returns `true`.

    When overriding the `equals` or `hashCode` methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (`o1 eq o2`), they should be equal to each other (`o1 == o2`) and they should hash to the same value (`o1.hashCode == o2.hashCode`).

    returns

      `true` if the argument is a reference to the receiver object; `false` otherwise.

    Definition Classes
      AnyRef

31. #### def equals(arg0: Any): Boolean

    The equality method for reference types.

    The equality method for reference types. Default implementation delegates to `eq`.

    See also `equals` in scala.Any.

    returns

      `true` if the receiver object is equivalent to the argument; `false` otherwise.

    Definition Classes
      AnyRef → Any

32. #### def exists(pred: (T) ⇒ Boolean): Boolean

    Tests whether a predicate holds for some element of this parallel iterable.

    Tests whether a predicate holds for some element of this parallel iterable.

    This method will use `abort` signalling capabilities. This means that splitters may send and read `abort` signals.

    pred

      a predicate used to test elements

    returns

      true if `p` holds for some element, false otherwise

    Definition Classes
      ParIterableLike → GenTraversableOnce

33. #### def filter(pred: (T) ⇒ Boolean): Repr

    Selects all elements of this parallel iterable which satisfy a predicate.

    Selects all elements of this parallel iterable which satisfy a predicate.

    pred

      the predicate used to test elements.

    returns

      a new parallel iterable consisting of all elements of this parallel iterable that satisfy the given predicate `p`. Their order may not be preserved.

    Definition Classes
      ParIterableLike → GenTraversableLike

34. #### def filterNot(pred: (T) ⇒ Boolean): Repr

    Selects all elements of this parallel iterable which do not satisfy a predicate.

    Selects all elements of this parallel iterable which do not satisfy a predicate.

    pred

      the predicate used to test elements.

    returns

      a new parallel iterable consisting of all elements of this parallel iterable that do not satisfy the given predicate `p`. Their order may not be preserved.

    Definition Classes
      ParIterableLike → GenTraversableLike

35. #### def finalize(): Unit

    Called by the garbage collector on the receiver object when there are no more references to the object.

    Called by the garbage collector on the receiver object when there are no more references to the object.

    The details of when and if the `finalize` method is invoked, as well as the interaction between `finalize` and non-local returns and exceptions, are all platform dependent.

    Attributes
      protected[java.lang]
    Definition Classes
      AnyRef
    Annotations
      @throws( classOf[java.lang.Throwable] )
    Note

      not specified by SLS as a member of AnyRef

36. #### def find(pred: (T) ⇒ Boolean): Option[T]

    Finds some element in the collection for which the predicate holds, if such an element exists.

    Finds some element in the collection for which the predicate holds, if such an element exists. The element may not necessarily be the first such element in the iteration order.

    If there are multiple elements obeying the predicate, the choice is nondeterministic.

    This method will use `abort` signalling capabilities. This means that splitters may send and read `abort` signals.

    pred

      predicate used to test the elements

    returns

      an option value with the element if such an element exists, or `None` otherwise

    Definition Classes
      ParIterableLike → GenTraversableOnce

37. #### def flatMap[B](f: (A) ⇒ GenTraversableOnce[B]): ParIterable[B]

    [use case] Builds a new collection by applying a function to all elements of this parallel iterable and using the elements of the resulting collections.

    [use case]

    Builds a new collection by applying a function to all elements of this parallel iterable 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 parallel iterable. 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 => 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)

    B

      the element type of the returned collection.

    f

      the function to apply to each element.

    returns

      a new parallel iterable resulting from applying the given collection-valued function `f` to each element of this parallel iterable and concatenating the results.

    Definition Classes
      ParIterableLike → GenTraversableLike
    Full Signature

    #### def flatMap[S, That](f: (T) ⇒ GenTraversableOnce[S])(implicit bf: CanBuildFrom[Repr, S, That]): That

38. #### def fold[U >: T](z: U)(op: (U, U) ⇒ U): U

    Folds the elements of this sequence using the specified associative binary operator.

    Folds the elements of this sequence using the specified associative binary operator. The order in which the elements are reduced is unspecified and may be nondeterministic.

    Note this method has a different signature than the `foldLeft` and `foldRight` methods of the trait `Traversable`. The result of folding may only be a supertype of this parallel collection's type parameter `T`.

    U

      a type parameter for the binary operator, a supertype of `T`.

    z

      a neutral element for the fold operation, it may be added to the result an arbitrary number of times, not changing the result (e.g. `Nil` for list concatenation, 0 for addition, or 1 for multiplication)

    op

      a binary operator that must be associative

    returns

      the result of applying fold operator `op` between all the elements and `z`

    Definition Classes
      ParIterableLike → GenTraversableOnce

39. #### def foldLeft[S](z: S)(op: (S, T) ⇒ S): S

    Applies a binary operator to a start value and all elements of this parallel iterable, going left to right.

    Applies a binary operator to a start value and all elements of this parallel iterable, going left to right.

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

    z

      the start value.

    op

      the binary operator.

    returns

      the result of inserting `op` between consecutive elements of this parallel iterable, going left to right with the start value `z` on the left:

          op(...op(z, x_1), x_2, ..., x_n)

      where `x1, ..., xn` are the elements of this parallel iterable.

    Definition Classes
      ParIterableLike → GenTraversableOnce

40. #### def foldRight[S](z: S)(op: (T, S) ⇒ S): S

    Applies a binary operator to all elements of this parallel iterable and a start value, going right to left.

    Applies a binary operator to all elements of this parallel iterable and a start value, going right to left.

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

    z

      the start value.

    op

      the binary operator.

    returns

      the result of inserting `op` between consecutive elements of this parallel iterable, going right to left with the start value `z` on the right:

          op(x_1, op(x_2, ... op(x_n, z)...))

      where `x1, ..., xn` are the elements of this parallel iterable.

    Definition Classes
      ParIterableLike → GenTraversableOnce

41. #### def forall(pred: (T) ⇒ Boolean): Boolean

    Tests whether a predicate holds for all elements of this parallel iterable.

    Tests whether a predicate holds for all elements of this parallel iterable.

    This method will use `abort` signalling capabilities. This means that splitters may send and read `abort` signals.

    pred

      a predicate used to test elements

    returns

      true if `p` holds for all elements, false otherwise

    Definition Classes
      ParIterableLike → GenTraversableOnce

42. #### def foreach[U](f: (T) ⇒ U): Unit

    Applies a function `f` to all the elements of parallel iterable in an undefined order.

    Applies a function `f` to all the elements of parallel iterable in an undefined order.

    U

      the result type of the function applied to each element, which is always discarded

    f

      function applied to each element

    Definition Classes
      ParIterableLike → GenTraversableLike → GenTraversableOnce

43. #### def formatted(fmtstr: String): String

    Returns string formatted according to given `format` string.

    Returns string formatted according to given `format` string. Format strings are as for `String.format` (@see java.lang.String.format).

    Implicit information
      This member is added by an implicit conversion from ParIterableLike[T, Repr, Sequential] to StringFormat[ParIterableLike[T, Repr, Sequential]] performed by method StringFormat in scala.Predef.
    Definition Classes
      StringFormat
    Annotations
      @inline()

44. #### final def getClass(): Class[_]

    A representation that corresponds to the dynamic class of the receiver object.

    A representation that corresponds to the dynamic class of the receiver object.

    The nature of the representation is platform dependent.

    returns

      a representation that corresponds to the dynamic class of the receiver object.

    Definition Classes
      AnyRef → Any
    Note

      not specified by SLS as a member of AnyRef

45. #### def groupBy[K](f: (T) ⇒ K): immutable.ParMap[K, Repr]

    Partitions this parallel iterable into a map of parallel iterables according to some discriminator function.

    Partitions this parallel iterable into a map of parallel iterables according to some discriminator function.

    Note: this method is not re-implemented by views. This means when applied to a view it will always force the view and return a new parallel iterable.

    K

      the type of keys returned by the discriminator function.

    f

      the discriminator function.

    returns

      A map from keys to parallel iterables such that the following invariant holds:

          (xs groupBy f)(k) = xs filter (x => f(x) == k)

      That is, every key `k` is bound to a parallel iterable of those elements `x` for which `f(x)` equals `k`.

    Definition Classes
      ParIterableLike → GenTraversableLike

46. #### def hasDefiniteSize: Boolean

    Definition Classes
      ParIterableLike → GenTraversableOnce

47. #### def hashCode(): Int

    The hashCode method for reference types.

    The hashCode method for reference types. See hashCode in scala.Any.

    returns

      the hash code value for this object.

    Definition Classes
      AnyRef → Any

48. #### def head: T

    Selects the first element of this parallel iterable.

    Selects the first element of this parallel iterable.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    returns

      the first element of this parallel iterable.

    Definition Classes
      ParIterableLike → GenTraversableLike
    Exceptions thrown

      `NoSuchElementException` if the parallel iterable is empty.

49. #### def headOption: Option[T]

    Optionally selects the first element.

    Optionally selects the first element.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    returns

      the first element of this parallel iterable if it is nonempty, `None` if it is empty.

    Definition Classes
      ParIterableLike → GenTraversableLike

50. #### def init: Repr

    Selects all elements except the last.

    Selects all elements except the last.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    returns

      a parallel iterable consisting of all elements of this parallel iterable except the last one.

    Definition Classes
      ParIterableLike → GenTraversableLike
    Exceptions thrown

      `UnsupportedOperationException` if the parallel iterable is empty.

51. #### def initTaskSupport(): Unit

    Attributes
      protected

52. #### def isEmpty: Boolean

    Tests whether the parallel iterable is empty.

    Tests whether the parallel iterable is empty.

    returns

      `true` if the parallel iterable contains no elements, `false` otherwise.

    Definition Classes
      ParIterableLike → GenTraversableOnce

53. #### final def isInstanceOf[T0]: Boolean

    Test whether the dynamic type of the receiver object is `T0`.

    Test whether the dynamic type of the receiver object is `T0`.

    Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression `1.isInstanceOf[String]` will return `false`, while the expression `List(1).isInstanceOf[List[String]]` will return `true`. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

    returns

      `true` if the receiver object is an instance of erasure of type `T0`; `false` otherwise.

    Definition Classes
      Any

54. #### def isStrictSplitterCollection: Boolean

    Denotes whether this parallel collection has strict splitters.

    Denotes whether this parallel collection has strict splitters.

    This is true in general, and specific collection instances may choose to override this method. Such collections will fail to execute methods which rely on splitters being strict, i.e. returning a correct value in the `remaining` method.

    This method helps ensure that such failures occur on method invocations, rather than later on and in unpredictable ways.

55. #### final def isTraversableAgain: Boolean

    Tests whether this parallel iterable can be repeatedly traversed.

    Tests whether this parallel iterable can be repeatedly traversed.

    returns

      `true`

    Definition Classes
      ParIterableLike → GenTraversableLike → GenTraversableOnce

56. #### def iterator: Splitter[T]

    Creates a new split iterator used to traverse the elements of this collection.

    Creates a new split iterator used to traverse the elements of this collection.

    By default, this method is implemented in terms of the protected `splitter` method.

    returns

      a split iterator

    Definition Classes
      ParIterableLike → GenIterableLike

57. #### def last: T

    Selects the last element.

    Selects the last element.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    returns

      The last element of this parallel iterable.

    Definition Classes
      ParIterableLike → GenTraversableLike
    Exceptions thrown

      `NoSuchElementException` If the parallel iterable is empty.

58. #### def lastOption: Option[T]

    Optionally selects the last element.

    Optionally selects the last element.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    returns

      the last element of this parallel iterable$ if it is nonempty, `None` if it is empty.

    Definition Classes
      ParIterableLike → GenTraversableLike

59. #### def map[B](f: (A) ⇒ B): ParIterable[B]

    [use case] Builds a new collection by applying a function to all elements of this parallel iterable.

    [use case]

    Builds a new collection by applying a function to all elements of this parallel iterable.

    B

      the element type of the returned collection.

    f

      the function to apply to each element.

    returns

      a new parallel iterable resulting from applying the given function `f` to each element of this parallel iterable and collecting the results.

    Definition Classes
      ParIterableLike → GenTraversableLike
    Full Signature

    #### def map[S, That](f: (T) ⇒ S)(implicit bf: CanBuildFrom[Repr, S, That]): That

60. #### def max: A

    [use case] Finds the largest element.

    [use case]

    Finds the largest element.

    returns

      the largest element of this parallel iterable.

    Definition Classes
      ParIterableLike → GenTraversableOnce
    Full Signature

    #### def max[U >: T](implicit ord: Ordering[U]): T

61. #### def maxBy[B](f: (A) ⇒ B): A

    [use case] Finds the first element which yields the largest value measured by function f.

    [use case]

    Finds the first element which yields the largest value measured by function f.

    B

      The result type of the function f.

    f

      The measuring function.

    returns

      the first element of this parallel iterable with the largest value measured by function f.

    Definition Classes
      ParIterableLike → GenTraversableOnce
    Full Signature

    #### def maxBy[S](f: (T) ⇒ S)(implicit cmp: Ordering[S]): T

62. #### def min: A

    [use case] Finds the smallest element.

    [use case]

    Finds the smallest element.

    returns

      the smallest element of this parallel iterable

    Definition Classes
      ParIterableLike → GenTraversableOnce
    Full Signature

    #### def min[U >: T](implicit ord: Ordering[U]): T

63. #### def minBy[B](f: (A) ⇒ B): A

    [use case] Finds the first element which yields the smallest value measured by function f.

    [use case]

    Finds the first element which yields the smallest value measured by function f.

    B

      The result type of the function f.

    f

      The measuring function.

    returns

      the first element of this parallel iterable with the smallest value measured by function f.

    Definition Classes
      ParIterableLike → GenTraversableOnce
    Full Signature

    #### def minBy[S](f: (T) ⇒ S)(implicit cmp: Ordering[S]): T

64. #### def mkString: String

    Displays all elements of this parallel iterable in a string.

    Displays all elements of this parallel iterable in a string.

    returns

      a string representation of this parallel iterable. In the resulting string the string representations (w.r.t. the method `toString`) of all elements of this parallel iterable follow each other without any separator string.

    Definition Classes
      ParIterableLike → GenTraversableOnce

65. #### def mkString(sep: String): String

    Displays all elements of this parallel iterable in a string using a separator string.

    Displays all elements of this parallel iterable in a string using a separator string.

    sep

      the separator string.

    returns

      a string representation of this parallel iterable. In the resulting string the string representations (w.r.t. the method `toString`) of all elements of this parallel iterable are separated by the string `sep`.

    Definition Classes
      ParIterableLike → GenTraversableOnce
    Example:

    1. `List(1, 2, 3).mkString("|") = "1|2|3"`

66. #### def mkString(start: String, sep: String, end: String): String

    Displays all elements of this parallel iterable in a string using start, end, and separator strings.

    Displays all elements of this parallel iterable in a string using start, end, and separator strings.

    start

      the starting string.

    sep

      the separator string.

    end

      the ending string.

    returns

      a string representation of this parallel iterable. 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 parallel iterable are separated by the string `sep`.

    Definition Classes
      ParIterableLike → GenTraversableOnce
    Example:

    1. `List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"`

67. #### final def ne(arg0: AnyRef): Boolean

    Equivalent to `!(this eq that)`.

    Equivalent to `!(this eq that)`.

    returns

      `true` if the argument is not a reference to the receiver object; `false` otherwise.

    Definition Classes
      AnyRef

68. #### def nonEmpty: Boolean

    Tests whether the parallel iterable is not empty.

    Tests whether the parallel iterable is not empty.

    returns

      `true` if the parallel iterable contains at least one element, `false` otherwise.

    Definition Classes
      ParIterableLike → GenTraversableOnce

69. #### final def notify(): Unit

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Definition Classes
      AnyRef
    Note

      not specified by SLS as a member of AnyRef

70. #### final def notifyAll(): Unit

    Wakes up all threads that are waiting on the receiver object's monitor.

    Wakes up all threads that are waiting on the receiver object's monitor.

    Definition Classes
      AnyRef
    Note

      not specified by SLS as a member of AnyRef

71. #### def par: Repr

    Returns a parallel implementation of this collection.

    Returns a parallel implementation of this collection.

    For most collection types, this method creates a new parallel collection by copying all the elements. For these collection, `par` takes linear time. Mutable collections in this category do not produce a mutable parallel collection that has the same underlying dataset, so changes in one collection will not be reflected in the other one.

    Specific collections (e.g. `ParArray` or `mutable.ParHashMap`) override this default behaviour by creating a parallel collection which shares the same underlying dataset. For these collections, `par` takes constant or sublinear time.

    All parallel collections return a reference to themselves.

    returns

      a parallel implementation of this collection

    Definition Classes
      ParIterableLike → CustomParallelizable → Parallelizable

72. #### def parCombiner: Combiner[T, Repr]

    The default `par` implementation uses the combiner provided by this method to create a new parallel collection.

    The default `par` implementation uses the combiner provided by this method to create a new parallel collection.

    returns

      a combiner for the parallel collection of type `ParRepr`

    Attributes
      protected[this]
    Definition Classes
      CustomParallelizable → Parallelizable

73. #### def partition(pred: (T) ⇒ Boolean): (Repr, Repr)

    Partitions this parallel iterable in two parallel iterables according to a predicate.

    Partitions this parallel iterable in two parallel iterables according to a predicate.

    pred

      the predicate on which to partition.

    returns

      a pair of parallel iterables: the first parallel iterable consists of all elements that satisfy the predicate `p` and the second parallel iterable consists of all elements that don't. The relative order of the elements in the resulting parallel iterables may not be preserved.

    Definition Classes
      ParIterableLike → GenTraversableLike

74. #### def product: A

    [use case] Multiplies up the elements of this collection.

    [use case]

    Multiplies up the elements of this collection.

    returns

      the product of all elements in this parallel iterable of numbers of type `Int`. Instead of `Int`, any other type `T` with an implicit `Numeric[T]` implementation can be used as element type of the parallel iterable and as result type of `product`. Examples of such types are: `Long`, `Float`, `Double`, `BigInt`.

    Definition Classes
      ParIterableLike → GenTraversableOnce
    Full Signature

    #### def product[U >: T](implicit num: Numeric[U]): U

75. #### def reduce[U >: T](op: (U, U) ⇒ U): U

    Reduces the elements of this sequence using the specified associative binary operator.

    Reduces the elements of this sequence using the specified associative binary operator.

    The order in which operations are performed on elements is unspecified and may be nondeterministic.

    Note this method has a different signature than the `reduceLeft` and `reduceRight` methods of the trait `Traversable`. The result of reducing may only be a supertype of this parallel collection's type parameter `T`.

    U

      A type parameter for the binary operator, a supertype of `T`.

    op

      A binary operator that must be associative.

    returns

      The result of applying reduce operator `op` between all the elements if the collection is nonempty.

    Definition Classes
      ParIterableLike → GenTraversableOnce
    Exceptions thrown

      `UnsupportedOperationException` if this parallel iterable is empty.

76. #### def reduceLeft[U >: T](op: (U, T) ⇒ U): U

77. #### def reduceLeftOption[U >: T](op: (U, T) ⇒ U): Option[U]

    Optionally applies a binary operator to all elements of this parallel iterable, going left to right.

    Optionally applies a binary operator to all elements of this parallel iterable, going left to right.

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

    op

      the binary operator.

    returns

      an option value containing the result of `reduceLeft(op)` is this parallel iterable is nonempty, `None` otherwise.

    Definition Classes
      ParIterableLike → GenTraversableOnce

78. #### def reduceOption[U >: T](op: (U, U) ⇒ U): Option[U]

    Optionally reduces the elements of this sequence using the specified associative binary operator.

    Optionally reduces the elements of this sequence using the specified associative binary operator.

    The order in which operations are performed on elements is unspecified and may be nondeterministic.

    Note this method has a different signature than the `reduceLeftOption` and `reduceRightOption` methods of the trait `Traversable`. The result of reducing may only be a supertype of this parallel collection's type parameter `T`.

    U

      A type parameter for the binary operator, a supertype of `T`.

    op

      A binary operator that must be associative.

    returns

      An option value containing result of applying reduce operator `op` between all the elements if the collection is nonempty, and `None` otherwise.

    Definition Classes
      ParIterableLike → GenTraversableOnce

79. #### def reduceRight[U >: T](op: (T, U) ⇒ U): U

    Applies a binary operator to all elements of this parallel iterable, going right to left.

    Applies a binary operator to all elements of this parallel iterable, going right to left.

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

    op

      the binary operator.

    returns

      the result of inserting `op` between consecutive elements of this parallel iterable, going right to left:

          op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))

      where `x1, ..., xn` are the elements of this parallel iterable.

    Definition Classes
      ParIterableLike → GenTraversableOnce
    Exceptions thrown

      `UnsupportedOperationException` if this parallel iterable is empty.

80. #### def reduceRightOption[U >: T](op: (T, U) ⇒ U): Option[U]

    Optionally applies a binary operator to all elements of this parallel iterable, going right to left.

    Optionally applies a binary operator to all elements of this parallel iterable, going right to left.

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

    op

      the binary operator.

    returns

      an option value containing the result of `reduceRight(op)` is this parallel iterable is nonempty, `None` otherwise.

    Definition Classes
      ParIterableLike → GenTraversableOnce

81. #### def repr: Repr

    Definition Classes
      ParIterableLike → GenTraversableLike

82. #### def reuse[S, That](oldc: Option[Combiner[S, That]], newc: Combiner[S, That]): Combiner[S, That]

    Optionally reuses an existing combiner for better performance.

    Optionally reuses an existing combiner for better performance. By default it doesn't - subclasses may override this behaviour. The provided combiner `oldc` that can potentially be reused will be either some combiner from the previous computational task, or `None` if there was no previous phase (in which case this method must return `newc`).

    oldc

      The combiner that is the result of the previous task, or `None` if there was no previous task.

    newc

      The new, empty combiner that can be used.

    returns

      Either `newc` or `oldc`.

    Attributes
      protected

83. #### def sameElements(that: GenIterable[A]): Boolean

    [use case] Checks if the other iterable collection contains the same elements in the same order as this parallel iterable.

    [use case]

    Checks if the other iterable collection contains the same elements in the same order as this parallel iterable.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    Note: will not terminate for infinite-sized collections.

    that

      the collection to compare with.

    returns

      `true`, if both collections contain the same elements in the same order, `false` otherwise.

    Definition Classes
      ParIterableLike → GenIterableLike
    Full Signature

    #### def sameElements[U >: T](that: GenIterable[U]): Boolean

84. #### def scan(z: T)(op: (T, T) ⇒ T): ParIterable[T]

    [use case] Computes a prefix scan of the elements of the collection.

    [use case]

    Computes a prefix scan of the elements of the collection.

    Note: The neutral element `z` may be applied more than once.

    z

      neutral element for the operator `op`

    op

      the associative operator for the scan

    returns

      a new parallel iterable containing the prefix scan of the elements in this parallel iterable

    Definition Classes
      ParIterableLike → GenTraversableLike
    Full Signature

    #### def scan[U >: T, That](z: U)(op: (U, U) ⇒ U)(implicit bf: CanBuildFrom[Repr, U, That]): That

85. #### def scanBlockSize: Int

    Attributes
      protected[this]

86. #### def scanLeft[S, That](z: S)(op: (S, T) ⇒ S)(implicit bf: CanBuildFrom[Repr, S, That]): That

    Produces a collection containing cumulative results of applying the operator going left to right.

    Produces a collection containing cumulative results of applying the operator going left to right.

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    That

      the actual type of the resulting collection

    z

      the initial value

    op

      the binary operator applied to the intermediate result and the element

    bf

      an implicit value of class `CanBuildFrom` which determines the result class `That` from the current representation type `Repr` and and the new element type `B`.

    returns

      collection with intermediate results

    Definition Classes
      ParIterableLike → GenTraversableLike

87. #### def scanRight[S, That](z: S)(op: (T, S) ⇒ S)(implicit bf: CanBuildFrom[Repr, S, That]): That

    Produces a collection containing cumulative results of applying the operator going right to left.

    Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    Example:

        List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)

    That

      the actual type of the resulting collection

    z

      the initial value

    op

      the binary operator applied to the intermediate result and the element

    bf

      an implicit value of class `CanBuildFrom` which determines the result class `That` from the current representation type `Repr` and and the new element type `B`.

    returns

      collection with intermediate results

    Definition Classes
      ParIterableLike → GenTraversableLike

88. #### def sequentially[S, That <: Parallel](b: (Sequential) ⇒ Parallelizable[S, That]): Repr

    Attributes
      protected[this]

89. #### def slice(unc_from: Int, unc_until: Int): Repr

    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.

    unc_from

      the lowest index to include from this parallel iterable.

    unc_until

      the lowest index to EXCLUDE from this parallel iterable.

    returns

      a parallel iterable containing the elements greater than or equal to index `from` extending up to (but not including) index `until` of this parallel iterable.

    Definition Classes
      ParIterableLike → GenTraversableLike

90. #### def span(pred: (T) ⇒ Boolean): (Repr, Repr)

    Splits this parallel iterable into a prefix/suffix pair according to a predicate.

    Splits this parallel iterable into a prefix/suffix pair according to a predicate.

    This method will use `indexFlag` signalling capabilities. This means that splitters may set and read the `indexFlag` state. The index flag is initially set to maximum integer value.

    pred

      the predicate used to test the elements

    returns

      a pair consisting of the longest prefix of the collection for which all the elements satisfy `pred`, and the rest of the collection

    Definition Classes
      ParIterableLike → GenTraversableLike

91. #### def splitAt(n: Int): (Repr, Repr)

    Splits this parallel iterable into two at a given position.

    Splits this parallel iterable into two 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.

    n

      the position at which to split.

    returns

      a pair of parallel iterables consisting of the first `n` elements of this parallel iterable, and the other elements.

    Definition Classes
      ParIterableLike → GenTraversableLike

92. #### def sum: A

    [use case] Sums up the elements of this collection.

    [use case]

    Sums up the elements of this collection.

    returns

      the sum of all elements in this parallel iterable of numbers of type `Int`. Instead of `Int`, any other type `T` with an implicit `Numeric[T]` implementation can be used as element type of the parallel iterable and as result type of `sum`. Examples of such types are: `Long`, `Float`, `Double`, `BigInt`.

    Definition Classes
      ParIterableLike → GenTraversableOnce
    Full Signature

    #### def sum[U >: T](implicit num: Numeric[U]): U

93. #### final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
      AnyRef

94. #### def tail: Repr

    Selects all elements except the first.

    Selects all elements except the first.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    returns

      a parallel iterable consisting of all elements of this parallel iterable except the first one.

    Definition Classes
      ParIterableLike → GenTraversableLike
    Exceptions thrown

      `UnsupportedOperationException` if the parallel iterable is empty.

95. #### def take(n: Int): Repr

    Selects first n elements.

    Selects first n elements.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    n

      the number of elements to take from this parallel iterable.

    returns

      a parallel iterable consisting only of the first `n` elements of this parallel iterable, or else the whole parallel iterable, if it has less than `n` elements.

    Definition Classes
      ParIterableLike → GenTraversableLike

96. #### def takeWhile(pred: (T) ⇒ Boolean): Repr

    Takes the longest prefix of elements that satisfy the predicate.

    Takes the longest prefix of elements that satisfy the predicate.

    This method will use `indexFlag` signalling capabilities. This means that splitters may set and read the `indexFlag` state. The index flag is initially set to maximum integer value.

    pred

      the predicate used to test the elements

    returns

      the longest prefix of this parallel iterable of elements that satisfy the predicate `pred`

    Definition Classes
      ParIterableLike → GenTraversableLike

97. #### implicit def task2ops[R, Tp](tsk: SSCTask[R, Tp]): TaskOps[R, Tp]

    Attributes
      protected

98. #### def tasksupport: TaskSupport

    The task support object which is responsible for scheduling and load-balancing tasks to processors.

    The task support object which is responsible for scheduling and load-balancing tasks to processors.

    See also

      scala.collection.parallel.TaskSupport

99. #### def tasksupport_=(ts: TaskSupport): Unit

    Changes the task support object which is responsible for scheduling and load-balancing tasks to processors.

    Changes the task support object which is responsible for scheduling and load-balancing tasks to processors.

    A task support object can be changed in a parallel collection after it has been created, but only during a quiescent period, i.e. while there are no concurrent invocations to parallel collection methods.

    Here is a way to change the task support of a parallel collection:

        import scala.collection.parallel._
        val pc = mutable.ParArray(1, 2, 3)
        pc.tasksupport = new ForkJoinTaskSupport(
          new scala.concurrent.forkjoin.ForkJoinPool(2))

    See also

      scala.collection.parallel.TaskSupport

100. #### def to[Col[_]]: Col[A]

     [use case] Converts this parallel iterable into another by copying all elements.

     [use case]

     Converts this parallel iterable into another by copying all elements.

     Note: will not terminate for infinite-sized collections.

     Col

       The collection type to build.

     returns

       a new collection containing all elements of this parallel iterable.

     Definition Classes
       ParIterableLike → GenTraversableOnce
     Full Signature

     #### def to[Col[_]](implicit cbf: CanBuildFrom[Nothing, T, Col[T]]): Col[T]

101. #### def toArray: Array[A]

     [use case] Converts this parallel iterable to an array.

     [use case]

     Converts this parallel iterable to an array.

     Note: will not terminate for infinite-sized collections.

     returns

       an array containing all elements of this parallel iterable. An `ClassTag` must be available for the element type of this parallel iterable.

     Definition Classes
       ParIterableLike → GenTraversableOnce
     Full Signature

     #### def toArray[U >: T](implicit arg0: ClassTag[U]): Array[U]

102. #### def toBuffer[U >: T]: Buffer[U]

     Uses the contents of this parallel iterable to create a new mutable buffer.

     Uses the contents of this parallel iterable to create a new mutable buffer.

     Note: will not terminate for infinite-sized collections.

     returns

       a buffer containing all elements of this parallel iterable.

     Definition Classes
       ParIterableLike → GenTraversableOnce

103. #### def toIndexedSeq: immutable.IndexedSeq[T]

     Converts this parallel iterable to an indexed sequence.

     Converts this parallel iterable to an indexed sequence.

     Note: will not terminate for infinite-sized collections.

     returns

       an indexed sequence containing all elements of this parallel iterable.

     Definition Classes
       ParIterableLike → GenTraversableOnce

104. #### def toIterable: ParIterable[T]

     Converts this parallel iterable to an iterable collection.

     Converts this parallel iterable to an iterable collection. Note that the choice of target `Iterable` is lazy in this default implementation as this `TraversableOnce` may be lazy and unevaluated (i.e. it may be an iterator which is only traversable once).

     Note: will not terminate for infinite-sized collections.

     returns

       an `Iterable` containing all elements of this parallel iterable.

     Definition Classes
       ParIterableLike → GenTraversableOnce

105. #### def toIterator: scala.Iterator[T]

     Returns an Iterator over the elements in this parallel iterable.

     Returns an Iterator over the elements in this parallel iterable. Will return the same Iterator if this instance is already an Iterator.

     Note: will not terminate for infinite-sized collections.

     returns

       an Iterator containing all elements of this parallel iterable.

     Definition Classes
       ParIterableLike → GenTraversableOnce

106. #### def toList: List[T]

     Converts this parallel iterable to a list.

     Converts this parallel iterable to a list.

     Note: will not terminate for infinite-sized collections.

     returns

       a list containing all elements of this parallel iterable.

     Definition Classes
       ParIterableLike → GenTraversableOnce

107. #### def toMap[T, U]: collection.Map[T, U]

     [use case] Converts this parallel iterable to a map.

     [use case]

     Converts this parallel iterable to a map. This method is unavailable unless the elements are members of Tuple2, each ((T, U)) becoming a key-value pair in the map. Duplicate keys will be overwritten by later keys: if this is an unordered collection, which key is in the resulting map is undefined.

     Note: will not terminate for infinite-sized collections.

     returns

       a map of type `immutable.Map[T, U]` containing all key/value pairs of type `(T, U)` of this parallel iterable.

     Definition Classes
       ParIterableLike → GenTraversableOnce
     Full Signature

     #### def toMap[K, V](implicit ev: <:<[T, (K, V)]): immutable.ParMap[K, V]

108. #### def toParArray: ParArray[T]

     Implicit information
       This member is added by an implicit conversion from ParIterableLike[T, Repr, Sequential] to CollectionsHaveToParArray[ParIterableLike[T, Repr, Sequential], T] performed by method CollectionsHaveToParArray in scala.collection.parallel. This conversion will take place only if an implicit value of type (ParIterableLike[T, Repr, Sequential]) ⇒ GenTraversableOnce[T] is in scope.
     Definition Classes
       CollectionsHaveToParArray

109. #### def toParCollection[U >: T, That](cbf: () ⇒ Combiner[U, That]): That

     Attributes
       protected

110. #### def toParMap[K, V, That](cbf: () ⇒ Combiner[(K, V), That])(implicit ev: <:<[T, (K, V)]): That

     Attributes
       protected

111. #### def toSeq: ParSeq[T]

     Converts this parallel iterable to a sequence.

     Converts this parallel iterable to a sequence. As with `toIterable`, it's lazy in this default implementation, as this `TraversableOnce` may be lazy and unevaluated.

     Note: will not terminate for infinite-sized collections.

     returns

       a sequence containing all elements of this parallel iterable.

     Definition Classes
       ParIterableLike → GenTraversableOnce

112. #### def toSet[U >: T]: immutable.ParSet[U]

     Converts this parallel iterable to a set.

     Converts this parallel iterable to a set.

     Note: will not terminate for infinite-sized collections.

     returns

       a set containing all elements of this parallel iterable.

     Definition Classes
       ParIterableLike → GenTraversableOnce

113. #### def toStream: Stream[T]

     Converts this parallel iterable to a stream.

     Converts this parallel iterable to a stream.

     returns

       a stream containing all elements of this parallel iterable.

     Definition Classes
       ParIterableLike → GenTraversableOnce

114. #### def toString(): String

     Creates a String representation of this object.

     Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.

     returns

       a String representation of the object.

     Definition Classes
       ParIterableLike → AnyRef → Any

115. #### def toTraversable: GenTraversable[T]

     Converts this parallel iterable to an unspecified Traversable.

     Converts this parallel iterable to an unspecified Traversable. Will return the same collection if this instance is already Traversable.

     Note: will not terminate for infinite-sized collections.

     returns

       a Traversable containing all elements of this parallel iterable.

     Definition Classes
       ParIterableLike → GenTraversableOnce

116. #### def toVector: Vector[T]

     Converts this parallel iterable to a Vector.

     Converts this parallel iterable to a Vector.

     Note: will not terminate for infinite-sized collections.

     returns

       a vector containing all elements of this parallel iterable.

     Definition Classes
       ParIterableLike → GenTraversableOnce

117. #### final def wait(): Unit

     Definition Classes
       AnyRef
     Annotations
       @throws( ... )

118. #### final def wait(arg0: Long, arg1: Int): Unit

     Definition Classes
       AnyRef
     Annotations
       @throws( ... )

119. #### final def wait(arg0: Long): Unit

     Definition Classes
       AnyRef
     Annotations
       @throws( ... )

120. #### def withFilter(pred: (T) ⇒ Boolean): Repr

121. #### def wrap[R](body: ⇒ R): NonDivisible[R]

     Attributes
       protected

122. #### def zip[B](that: GenIterable[B]): ParIterable[(A, B)]

     [use case] Returns a parallel iterable formed from this parallel iterable and another iterable collection by combining corresponding elements in pairs.

     [use case]

     Returns a parallel iterable formed from this parallel iterable and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.

     Note: might return different results for different runs, unless the underlying collection type is ordered.

     B

       the type of the second half of the returned pairs

     that

       The iterable providing the second half of each result pair

     returns

       a new parallel iterable containing pairs consisting of corresponding elements of this parallel iterable and `that`. The length of the returned collection is the minimum of the lengths of this parallel iterable and `that`.

     Definition Classes
       ParIterableLike → GenIterableLike
     Full Signature

     #### def zip[U >: T, S, That](that: GenIterable[S])(implicit bf: CanBuildFrom[Repr, (U, S), That]): That

123. #### def zipAll[B](that: Iterable[B], thisElem: A, thatElem: B): ParIterable[(A, B)]

     [use case] Returns a parallel iterable formed from this parallel iterable and another iterable collection by combining corresponding elements in pairs.

     [use case]

     Returns a parallel iterable formed from this parallel iterable and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.

     Note: might return different results for different runs, unless the underlying collection type is ordered.

     B

       the type of the second half of the returned pairs

     that

       The iterable providing the second half of each result pair

     thisElem

       the element to be used to fill up the result if this parallel iterable is shorter than `that`.

     thatElem

       the element to be used to fill up the result if `that` is shorter than this parallel iterable.

     returns

       a new parallel iterable containing pairs consisting of corresponding elements of this parallel iterable and `that`. The length of the returned collection is the maximum of the lengths of this parallel iterable and `that`. If this parallel iterable is shorter than `that`, `thisElem` values are used to pad the result. If `that` is shorter than this parallel iterable, `thatElem` values are used to pad the result.

     Definition Classes
       ParIterableLike → GenIterableLike
     Full Signature

     #### def zipAll[S, U >: T, That](that: GenIterable[S], thisElem: U, thatElem: S)(implicit bf: CanBuildFrom[Repr, (U, S), That]): That

124. #### def zipWithIndex: ParIterable[(A, Int)]

     [use case] Zips this parallel iterable with its indices.

     [use case]

     Zips this parallel iterable with its indices.

     Note: might return different results for different runs, unless the underlying collection type is ordered.

     returns

       A new parallel iterable containing pairs consisting of all elements of this parallel iterable paired with their index. Indices start at `0`.

     Definition Classes
       ParIterableLike → GenIterableLike
     Full Signature

     #### def zipWithIndex[U >: T, That](implicit bf: CanBuildFrom[Repr, (U, Int), That]): That

     Example:

     1. `List("a", "b", "c").zipWithIndex = List(("a", 0), ("b", 1), ("c", 2))`

125. #### def →[B](y: B): (ParIterableLike[T, Repr, Sequential], B)

     Implicit information
       This member is added by an implicit conversion from ParIterableLike[T, Repr, Sequential] to ArrowAssoc[ParIterableLike[T, Repr, Sequential]] performed by method ArrowAssoc in scala.Predef.
     Definition Classes
       ArrowAssoc

### Deprecated Value Members

1. #### def view: IterableView[T, Sequential]

   Annotations
     @deprecated
   Deprecated

     (Since version 2.11.0) Use .seq.view instead

### Inherited from HasNewCombiner[T, Repr]

### Inherited from Parallel

### Inherited from CustomParallelizable[T, Repr]

### Inherited from GenIterableLike[T, Repr]

### Inherited from GenTraversableLike[T, Repr]

### Inherited from Parallelizable[T, Repr]

### Inherited from GenTraversableOnce[T]

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion CollectionsHaveToParArray from ParIterableLike[T, Repr, Sequential] to CollectionsHaveToParArray[ParIterableLike[T, Repr, Sequential], T]

### Inherited by implicit conversion any2stringadd from ParIterableLike[T, Repr, Sequential] to any2stringadd[ParIterableLike[T, Repr, Sequential]]

### Inherited by implicit conversion StringFormat from ParIterableLike[T, Repr, Sequential] to StringFormat[ParIterableLike[T, Repr, Sequential]]

### Inherited by implicit conversion Ensuring from ParIterableLike[T, Repr, Sequential] to Ensuring[ParIterableLike[T, Repr, Sequential]]

### Inherited by implicit conversion ArrowAssoc from ParIterableLike[T, Repr, Sequential] to ArrowAssoc[ParIterableLike[T, Repr, Sequential]]

### Ungrouped