A sequential collection containing the same elements as this collection

A more refined version of the iterator found in the ParallelIterable trait, this iterator can be split into arbitrary subsets of iterators.

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).

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.

The factory companion object that builds instances of class mutable.ParSeq. (or its Iterable superclass where class mutable.ParSeq is not a Seq.)

Tests whether every element of this parallel iterable relates to the corresponding element of another parallel sequence by satisfying a test predicate.

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

Builds a new parallel iterable from this parallel iterable without any duplicate elements.

Note: will not terminate for infinite-sized collections.

This trait defines a new, more general split operation and reimplements the split operation of ParallelIterable trait using the new split operation.

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.

Tests whether this parallel iterable ends with the given collection.

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

Tests whether this parallel iterable ends with the given parallel sequence.

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

The equals method for arbitrary parallel sequences. Compares this parallel sequence to some other object.

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.

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.

Converts this mutable parallel sequence of traversable collections into a mutable parallel sequence formed by the elements of these traversable collections.

The resulting collection's type will be guided by the static type of mutable parallel sequence. 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)

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.

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.

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

The generic builder that builds instances of $Coll at arbitrary element types.

Finds index of first occurrence of some value in this parallel iterable after or at some start index.

Finds index of first occurrence of some value in this parallel iterable.

Finds the first element satisfying some 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.

Finds index of first element satisfying some predicate.

Note: may not terminate for infinite-sized collections.

Computes the multiset intersection between this mutable parallel sequence and another sequence.

Note: may not terminate for infinite-sized collections.

Tests whether this parallel iterable contains given index.

The implementations of methods apply and isDefinedAt turn a ParSeq[T] into a PartialFunction[Int, T].

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.

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.

Finds index of last occurrence of some value in this parallel iterable before or at a given end index.

Finds index of last occurrence of some value in this parallel iterable.

Note: will not terminate for infinite-sized collections.

This trait defines a new, more general split operation and reimplements the split operation of ParallelIterable trait using the new split operation.

Finds the last element satisfying some 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 minimum integer value.

Finds index of last element satisfying some predicate.

Note: will not terminate for infinite-sized collections.

This trait defines a new, more general split operation and reimplements the split operation of ParallelIterable trait using the new split operation.

The builder that builds instances of type $Coll[A]

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.

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

Overload of patch that takes a sequential collection as parameter

Returns the length of the longest prefix whose elements all satisfy some predicate.

Note: may not terminate for infinite-sized collections.

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.

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.

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).

Computes a prefix scan of the elements of the collection.

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

Returns the length of the longest segment of elements starting at a given position satisfying some 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.

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.

Tests whether this parallel iterable contains the given sequence at a given index.

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

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.

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 java.util.concurrent.ForkJoinPool(2))

Transposes this collection of traversable collections into a collection of collections.

The resulting collection's type will be guided by the static type of collection. For example:

val xs = List(
           Set(1, 2, 3),
           Set(4, 5, 6)).transpose
// xs == List(
//         List(1, 4),
//         List(2, 5),
//         List(3, 6))

val ys = Vector(
           List(1, 2, 3),
           List(4, 5, 6)).transpose
// ys == Vector(
//         Vector(1, 4),
//         Vector(2, 5),
//         Vector(3, 6))

Overload of union that takes a sequential collection as parameter

Produces a new sequence which contains all elements of this parallel iterable and also all elements of a given sequence. xs union ys is equivalent to xs ++ ys.

Another way to express this is that xs union ys computes the order-preserving multi-set union of xs and ys. union is hence a counter-part of diff and intersect which also work on multi-sets.

Note: will not terminate for infinite-sized collections.

This trait defines a new, more general split operation and reimplements the split operation of ParallelIterable trait using the new split operation.

Converts this collection of pairs into two collections of the first and second half of each pair.

val xs = $Coll(
           (1, "one"),
           (2, "two"),
           (3, "three")).unzip
// xs == ($Coll(1, 2, 3),
//        $Coll(one, two, three))

Converts this collection of triples into three collections of the first, second, and third element of each triple.

val xs = $Coll(
           (1, "one", '1'),
           (2, "two", '2'),
           (3, "three", '3')).unzip3
// xs == ($Coll(1, 2, 3),
//        $Coll(one, two, three),
//        $Coll(1, 2, 3))

Zips this parallel iterable with its indices.