Performs two tasks in parallel, and waits for both to finish.
Sequentially performs one task after another.
Used to iterate elements using indices
Selects an element by its index in the general sequence.
Example:
scala> val x = List(1, 2, 3, 4, 5) x: List[Int] = List(1, 2, 3, 4, 5) scala> x(3) res1: Int = 4
The index to select.
the element of this general sequence at index idx, where 0 indicates the first element.
IndexOutOfBoundsException if idx does not satisfy 0 <= idx < length.
The length of the general sequence.
Note: will not terminate for infinite-sized collections.
Note: xs.length and xs.size yield the same result.
the number of elements in this general sequence.
IllegalArgumentException if the length of the sequence cannot be represented in an Int, for example, (-1 to Int.MaxValue).length.
A more refined version of the iterator found in the ParallelIterable trait, this iterator can be split into arbitrary subsets of iterators.
an iterator that can be split into subsets of precise size
Defines the prefix of this object's toString representation.
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.
Test two objects for inequality.
true if !(this == that), false otherwise.
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.
a hash value consistent with ==
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.
the class of the returned collection. Where possible, That is the same class as the current collection class Repr, but this depends on the element type B being admissible for that class, which means that an implicit instance of type CanBuildFrom[Repr, B, That] is found.
the traversable to append.
an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.
a new collection of type That which contains all elements of this parallel iterable followed by all elements of that.
A copy of the parallel iterable with an element prepended.
Note that :-ending operators are right associative (see example). A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.
Also, the original parallel iterable is not modified, so you will want to capture the result.
Example:
scala> val x = List(1) x: List[Int] = List(1) scala> val y = 2 +: x y: List[Int] = List(2, 1) scala> println(x) List(1)
the prepended element
a new parallel iterable consisting of elem followed by all elements of this parallel iterable.
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.
the start value.
the binary operator.
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.
A copy of this parallel iterable with an element appended.
A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.
Note: will not terminate for infinite-sized collections.
Example:
scala> val a = List(1) a: List[Int] = List(1) scala> val b = a :+ 2 b: List[Int] = List(1, 2) scala> println(a) List(1)
the appended element
a new parallel iterable consisting of all elements of this parallel iterable followed by elem.
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
the start value
the binary operator
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.
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
true if the receiver object is equivalent to the argument; false otherwise.
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).
the type of accumulated results
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
an operator used to accumulate results within a partition
an associative operator used to combine results from different partitions
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.
the receiver object.
ClassCastException if the receiver object is not an instance of the erasure of type T0.
Create a copy of the receiver object.
The default implementation of the clone method is platform dependent.
a copy of the receiver object.
Builds a new collection by applying a partial function to all elements of this parallel iterable on which the function is defined.
the element type of the returned collection.
the partial function which filters and maps the parallel iterable.
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.
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.
Copies the elements of this parallel iterable to an array. Fills the given array xs with at most len elements of this parallel iterable, starting at position start. Copying will stop once either the end of the current parallel iterable is reached, or the end of the target array is reached, or len elements have been copied.
Note: will not terminate for infinite-sized collections.
the array to fill.
the starting index.
the maximal number of elements to copy.
Copies the elements 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 target array is reached.
Note: will not terminate for infinite-sized collections.
the array to fill.
the starting index.
Copies the elements 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 target array is reached.
Note: will not terminate for infinite-sized collections.
the array to fill.
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.
the type of the elements of that
the other parallel sequence
the test predicate, which relates elements from both sequences
true if both parallel sequences have the same length and p(x, y) is true for all corresponding elements x of this parallel iterable and y of that, otherwise false
Counts the number of elements in the parallel iterable which satisfy a predicate.
the predicate used to test elements.
the number of elements satisfying the predicate p.
Computes the multiset difference between this parallel iterable and another sequence.
Note: will not terminate for infinite-sized collections.
the sequence of elements to remove
a new parallel iterable which contains all elements of this parallel iterable except some of occurrences of elements that also appear in that. If an element value x appears n times in that, then the first n occurrences of x will not form part of the result, but any following occurrences will.
Builds a new parallel iterable from this parallel iterable without any duplicate elements.
Note: will not terminate for infinite-sized collections.
A new parallel iterable which contains the first occurrence of every element of this parallel iterable.
Selects all elements except first n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the number of elements to drop from this parallel iterable.
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. If n is negative, don't drop any 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.
the predicate used to test the elements
a collection composed of all the elements after the longest prefix of elements in this parallel iterable that satisfy the predicate pred
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 type of the elements of that sequence
the sequence to test
true if this parallel iterable has that as a suffix, false otherwise
Tests whether the argument (that) 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:
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).
true if the argument is a reference to the receiver object; false otherwise.
The equals method for arbitrary sequences. Compares this sequence to some other object.
The object to compare the sequence to
true if that is a sequence that has the same elements as this sequence in the same order, false otherwise
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.
a predicate used to test elements
true if p holds for some element, false otherwise
Selects all elements of this parallel iterable which satisfy a predicate.
the predicate used to test elements.
a new parallel iterable consisting of all elements of this parallel iterable that satisfy the given predicate p. Their order may not be preserved.
Selects all elements of this parallel iterable which do not satisfy a predicate.
the predicate used to test elements.
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.
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.
not specified by SLS as a member of AnyRef
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.
predicate used to test the elements
an option value with the element if such an element exists, or None otherwise
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)
the element type of the returned collection.
the function to apply to each element.
a new parallel iterable resulting from applying the given collection-valued function f to each element of this parallel iterable and concatenating the results.
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.
a type parameter for the binary operator, a supertype of T.
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)
a binary operator that must be associative
the result of applying fold operator op between all the elements and z
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.
the start value.
the binary operator.
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. Returns z if this parallel iterable is empty.
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.
the start value.
the binary operator.
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. Returns z if this parallel iterable is empty.
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.
a predicate used to test elements
true if p holds for all elements, false otherwise
Applies a function f to all the elements of parallel iterable in an undefined order.
the result type of the function applied to each element, which is always discarded
function applied to each element
Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).
Returns the runtime class representation of the object.
a class object corresponding to the runtime type of the receiver.
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.
the type of keys returned by the discriminator function.
the discriminator function.
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.
Tests whether this parallel iterable is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as Stream, the predicate returns true if all elements have been computed. It returns false if the stream is not yet evaluated to the end. Non-empty Iterators usually return false even if they were created from a collection with a known finite size.
Note: many collection methods will not work on collections of infinite sizes. The typical failure mode is an infinite loop. These methods always attempt a traversal without checking first that hasDefiniteSize returns true. However, checking hasDefiniteSize can provide an assurance that size is well-defined and non-termination is not a concern.
true if this collection is known to have finite size, false otherwise.
Hashcodes for GenSeq produce a value from the hashcodes of all the elements of the general sequence.
the hash code value for this object.
Selects the first element of this parallel iterable.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the first element of this parallel iterable.
NoSuchElementException if the parallel iterable is empty.
Optionally selects the first element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the first element of this parallel iterable if it is nonempty, None if it is empty.
Finds index of first occurrence of some value in this parallel iterable after or at some start index.
Note: may not terminate for infinite-sized collections.
the element value to search for.
the start index
the index >= from of the first element of this parallel iterable that is equal (as determined by ==) to elem, or -1, if none exists.
Finds index of first occurrence of some value in this parallel iterable.
Note: may not terminate for infinite-sized collections.
the element value to search for.
the index of the first element of this parallel iterable that is equal (as determined by ==) to elem, or -1, if none exists.
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.
the predicate used to test the elements
the starting offset for the search
the index >= from of the first element of this parallel iterable that satisfies the predicate p, or -1, if none exists
Finds index of first element satisfying some predicate.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
the index of the first element of this general sequence that satisfies the predicate p, or -1, if none exists.
Selects all elements except the last.
Note: might return different results for different runs, unless the underlying collection type is ordered.
a parallel iterable consisting of all elements of this parallel iterable except the last one.
UnsupportedOperationException if the parallel iterable is empty.
Computes the multiset intersection between this parallel iterable and another sequence.
Note: may not terminate for infinite-sized collections.
the sequence of elements to intersect with.
a new parallel iterable which contains all elements of this parallel iterable which also appear in that. If an element value x appears n times in that, then the first n occurrences of x will be retained in the result, but any following occurrences will be omitted.
Tests whether this general sequence contains given index.
The implementations of methods apply and isDefinedAt turn a Seq[A] into a PartialFunction[Int, A].
the index to test
true if this general sequence contains an element at position idx, false otherwise.
Tests whether the parallel iterable is empty.
Note: Implementations in subclasses that are not repeatedly traversable must take care not to consume any elements when isEmpty is called.
true if the parallel iterable contains no elements, false otherwise.
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.
true if the receiver object is an instance of erasure of type T0; false otherwise.
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.
Tests whether this parallel iterable can be repeatedly traversed.
true
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.
a split iterator
Selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
The last element of this parallel iterable.
NoSuchElementException If the parallel iterable is empty.
Finds index of last occurrence of some value in this parallel iterable before or at a given end index.
the element value to search for.
the end index.
the index <= end of the last element of this parallel iterable that is equal (as determined by ==) to elem, or -1, if none exists.
Finds index of last occurrence of some value in this parallel iterable.
Note: will not terminate for infinite-sized collections.
the element value to search for.
the index of the last element of this parallel iterable that is equal (as determined by ==) to elem, or -1, if none exists.
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.
the predicate used to test the elements
the maximum offset for the search
the index <= end of the first element of this parallel iterable that satisfies the predicate p, or -1, if none exists
Finds index of last element satisfying some predicate.
Note: will not terminate for infinite-sized collections.
the predicate used to test elements.
the index of the last element of this general sequence that satisfies the predicate p, or -1, if none exists.
Optionally selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the last element of this parallel iterable$ if it is nonempty, None if it is empty.
Builds a new collection by applying a function to all elements of this parallel iterable.
the element type of the returned collection.
the function to apply to each element.
a new parallel iterable resulting from applying the given function f to each element of this parallel iterable and collecting the results.
Finds the largest element.
the largest element of this parallel iterable.
UnsupportedOperationException if this parallel iterable is empty.
Finds the first element which yields the largest value measured by function f.
The result type of the function f.
The measuring function.
the first element of this parallel iterable with the largest value measured by function f.
UnsupportedOperationException if this parallel iterable is empty.
Finds the smallest element.
the smallest element of this parallel iterable
UnsupportedOperationException if this parallel iterable is empty.
Finds the first element which yields the smallest value measured by function f.
The result type of the function f.
The measuring function.
the first element of this parallel iterable with the smallest value measured by function f.
UnsupportedOperationException if this parallel iterable is empty.
Displays all elements of this parallel iterable in a string.
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.
Displays all elements of this parallel iterable in a string using a separator string.
the separator string.
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.
List(1, 2, 3).mkString("|") = "1|2|3"
Displays all elements of this parallel iterable in a string using start, end, and separator strings.
the starting string.
the separator string.
the ending string.
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.
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Equivalent to !(this eq that).
true if the argument is not a reference to the receiver object; false otherwise.
Tests whether the parallel iterable is not empty.
true if the parallel iterable contains at least one element, false otherwise.
Wakes up a single thread that is waiting on the receiver object's monitor.
not specified by SLS as a member of AnyRef
Wakes up all threads that are waiting on the receiver object's monitor.
not specified by SLS as a member of AnyRef
A copy of this parallel iterable with an element value appended until a given target length is reached.
the target length
the padding value
a new parallel iterable consisting of all elements of this parallel iterable followed by the minimal number of occurrences of elem so that the resulting parallel iterable has a length of at least len.
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.
a parallel implementation of this collection
The default par implementation uses the combiner provided by this method to create a new parallel collection.
a combiner for the parallel collection of type ParRepr
Partitions this parallel iterable in two parallel iterables according to a predicate.
the predicate on which to partition.
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.
Produces a new parallel iterable where a slice of elements in this parallel iterable is replaced by another sequence.
the index of the first replaced element
the number of elements to drop in the original parallel iterable
a new parallel iterable consisting of all elements of this parallel iterable except that replaced elements starting from from are replaced by patch.
Returns the length of the longest prefix whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
the length of the longest prefix of this general sequence such that every element of the segment satisfies the predicate p.
Multiplies up the elements of this collection.
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.
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.
A type parameter for the binary operator, a supertype of T.
A binary operator that must be associative.
The result of applying reduce operator op between all the elements if the collection is nonempty.
UnsupportedOperationException if this parallel iterable is empty.
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.
the binary operator.
an option value containing the result of reduceLeft(op) if this parallel iterable is nonempty, None otherwise.
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.
A type parameter for the binary operator, a supertype of T.
A binary operator that must be associative.
An option value containing result of applying reduce operator op between all the elements if the collection is nonempty, and None otherwise.
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.
the binary operator.
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.
UnsupportedOperationException if this parallel iterable is empty.
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.
the binary operator.
an option value containing the result of reduceRight(op) if this parallel iterable is nonempty, None otherwise.
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).
The combiner that is the result of the previous task, or None if there was no previous task.
The new, empty combiner that can be used.
Either newc or oldc.
Returns new parallel iterable with elements in reversed order.
Note: will not terminate for infinite-sized collections.
A new parallel iterable with all elements of this parallel iterable in reversed order.
Builds a new collection by applying a function to all elements of this parallel iterable and collecting the results in reversed order.
Note: will not terminate for infinite-sized collections.
Note: xs.reverseMap(f) is the same as xs.reverse.map(f) but might be more efficient.
the element type of the returned collection.
the function to apply to each element.
a new parallel iterable resulting from applying the given function f to each element of this parallel iterable and collecting the results in reversed order.
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.
the collection to compare with.
true, if both collections contain the same elements in the same order, false otherwise.
Computes a prefix scan of the elements of the collection.
Note: The neutral element z may be applied more than once.
neutral element for the operator op
the associative operator for the scan
a new parallel iterable containing the prefix scan of the elements in this parallel iterable
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.
the actual type of the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.
collection with intermediate results
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)
the actual type of the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.
collection with intermediate results
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.
the predicate used to test the elements
the starting offset for the search
the length of the longest segment of elements starting at from and satisfying the predicate
The size of this parallel iterable.
Note: will not terminate for infinite-sized collections.
the number of elements in this parallel iterable.
The size of this collection or iterator, if it can be cheaply computed
the number of elements in this collection or iterator, or -1 if the size cannot be determined cheaply
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.
the lowest index to include from this parallel iterable.
the lowest index to EXCLUDE from this parallel iterable.
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.
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.
the predicate used to test the elements
a pair consisting of the longest prefix of the collection for which all the elements satisfy pred, and the rest of the collection
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.
the position at which to split.
a pair of parallel iterables consisting of the first n elements of this parallel iterable, and the other elements.
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.
the element type of that parallel sequence
the parallel sequence this sequence is being searched for
the starting offset for the search
true if there is a sequence that starting at offset in this sequence, false otherwise
Tests whether this general sequence starts with the given sequence.
the sequence to test
true if this collection has that as a prefix, false otherwise.
Sums up the elements of this collection.
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.
Selects all elements except the first.
Note: might return different results for different runs, unless the underlying collection type is ordered.
a parallel iterable consisting of all elements of this parallel iterable except the first one.
UnsupportedOperationException if the parallel iterable is empty.
Selects first n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the number of elements to take from this parallel iterable.
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. If n is negative, returns an empty parallel iterable.
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 predicate used to test the elements
the longest prefix of this parallel iterable of elements that satisfy the predicate pred
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))
Converts this parallel iterable into another by copying all elements.
Note: will not terminate for infinite-sized collections.
The collection type to build.
a new collection containing all elements of this parallel iterable.
Converts this parallel iterable to an array.
Note: will not terminate for infinite-sized collections.
an array containing all elements of this parallel iterable. An ClassTag must be available for the element type of this parallel iterable.
Uses the contents of this parallel iterable to create a new mutable buffer.
Note: will not terminate for infinite-sized collections.
a buffer containing all elements of this parallel iterable.
Converts this parallel iterable to an indexed sequence.
Note: will not terminate for infinite-sized collections.
an indexed sequence containing all elements of this parallel iterable.
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.
an Iterable containing all elements of 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.
an Iterator containing all elements of this parallel iterable.
Converts this parallel iterable to a list.
Note: will not terminate for infinite-sized collections.
a list containing all elements of this parallel iterable.
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.
a map of type immutable.Map[T, U] containing all key/value pairs of type (T, U) of this parallel iterable.
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.
a sequence containing all elements of this parallel iterable.
Converts this parallel iterable to a set.
Note: will not terminate for infinite-sized collections.
a set containing all elements of this parallel iterable.
Converts this parallel iterable to a stream.
a stream containing all elements of this parallel iterable.
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.
a String representation of the object.
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.
a Traversable containing all elements of this parallel iterable.
Converts this parallel iterable to a Vector.
Note: will not terminate for infinite-sized collections.
a vector containing all elements of this parallel iterable.
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.
the sequence to add.
a new parallel iterable which contains all elements of this parallel iterable followed by all elements of that.
A copy of this parallel iterable with one single replaced element.
the position of the replacement
the replacing element
a copy of this parallel iterable with the element at position index replaced by elem.
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.
the type of the second half of the returned pairs
The iterable providing the second half of each result pair
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.
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.
the type of the second half of the returned pairs
The iterable providing the second half of each result pair
the element to be used to fill up the result if this parallel iterable is shorter than that.
the element to be used to fill up the result if that is shorter than this parallel iterable.
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.
Zips this parallel iterable with its indices.
Note: might return different results for different runs, unless the underlying collection type is ordered.
A new parallel iterable containing pairs consisting of all elements of this parallel iterable paired with their index. Indices start at 0.
List("a", "b", "c").zipWithIndex = List(("a", 0), ("b", 1), ("c", 2))
© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.12.9/scala/collection/parallel/ParSeqLike.html
A template trait for sequences of type
ParSeq[T], representing parallel sequences with element typeT.Parallel sequences inherit the
Seqtrait. Their indexing and length computations are defined to be efficient. Like their sequential counterparts they always have a defined order of elements. This means they will produce resulting parallel sequences in the same way sequential sequences do. However, the order in which they perform bulk operations on elements to produce results is not defined and is generally nondeterministic. If the higher-order functions given to them produce no sideeffects, then this won't be noticeable.This trait defines a new, more general
splitoperation and reimplements thesplitoperation ofParallelIterabletrait using the newsplitoperation.the type of the elements contained in this collection
the type of the actual collection containing the elements
the type of the sequential version of this parallel collection