ParSeqLike
A template trait for sequences of type ParSeq[T], representing
parallel sequences with element type T.
A template trait for sequences of type ParSeq[T], representing
parallel sequences with element type T.
Parallel sequences inherit the Seq trait. 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.
- Type Params
- Repr
the type of the actual collection containing the elements
- Sequential
the type of the sequential version of this parallel collection
- T
the type of the elements contained in this collection
Type members
Classlikes
Used to iterate elements using indices
Used to iterate elements using indices
Inherited classlikes
Standard accessor task that iterates over the elements of the collection.
Standard accessor task that iterates over the elements of the collection.
- Type Params
- R
type of the result of this method (
Rfor result).- Tp
the representation type of the task at hand.
- Inherited from
- ParIterableLike
- Inherited from
- ParIterableLike
Inherited types
Value members
Concrete methods
Tests whether every element of this parallel iterable relates to the corresponding element of another parallel sequence by satisfying a test predicate.
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.
- Type Params
- S
the type of the elements of
that
- Value Params
- p
the test predicate, which relates elements from both sequences
- that
the other parallel sequence
- Returns
trueif both parallel sequences have the same length andp(x, y)istruefor all corresponding elementsxof this parallel iterable andyofthat, otherwisefalse
Builds a new parallel iterable from this parallel iterable without any duplicate elements.
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.
- Returns
A new parallel iterable which contains the first occurrence of every element of this parallel iterable.
Tests whether this parallel iterable ends with the given parallel sequence.
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.
- Type Params
- S
the type of the elements of
thatsequence
- Value Params
- that
the sequence to test
- Returns
trueif this parallel iterable hasthatas a suffix,falseotherwise
Tests whether this parallel iterable ends with the given collection.
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.
- Type Params
- S
the type of the elements of
thatsequence
- Value Params
- that
the sequence to test
- Returns
trueif this parallel iterable hasthatas a suffix,falseotherwise
The equals method for arbitrary parallel sequences. Compares this parallel sequence to some other object.
The equals method for arbitrary parallel sequences. Compares this parallel sequence to some other object.
- Value Params
- that
The object to compare the sequence to
- Returns
trueifthatis a sequence that has the same elements as this sequence in the same order,falseotherwise- Definition Classes
- Equals -> Any
Finds index of first occurrence of some value in this parallel iterable.
Finds index of first occurrence of some value in this parallel iterable.
- Type Params
- B
the type of the element
elem.
- Value Params
- elem
the element value to search for.
- Returns
the index of the first element of this parallel iterable that is equal (as determined by
==) toelem, or-1, if none exists.
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 after or at some start index.
- Type Params
- B
the type of the element
elem.
- Value Params
- elem
the element value to search for.
- from
the start index
- Returns
the index
>= fromof the first element of this parallel iterable that is equal (as determined by==) toelem, or-1, if none exists.
Finds index of first element satisfying some predicate.
Finds index of first element satisfying some predicate.
Note: may not terminate for infinite-sized collections.
- Value Params
- p
the predicate used to test elements.
- Returns
the index of the first element of this parallel iterable that satisfies the predicate
p, or-1, if none exists.
Finds the first element satisfying some predicate.
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.
- Value Params
- from
the starting offset for the search
- p
the predicate used to test the elements
- Returns
the index
>= fromof the first element of this parallel iterable that satisfies the predicatep, or-1, if none exists
Computes the multiset intersection between this parallel iterable and another sequence.
Computes the multiset intersection between this parallel iterable and another sequence.
- Type Params
- U
the element type of
thatparallel sequence
- Value Params
- that
the sequence of elements to intersect with.
- Returns
a new collection of type
Thatwhich contains all elements of this parallel iterable which also appear inthat. If an element valuexappears ''n'' times inthat, then the first ''n'' occurrences ofxwill be retained in the result, but any following occurrences will be omitted.
Tests whether this parallel iterable contains given index.
Tests whether this parallel iterable contains given index.
The implementations of methods apply and isDefinedAt turn a ParSeq[T] into
a PartialFunction[Int, T].
- Value Params
- idx
the index to test
- Returns
trueif this parallel iterable contains an element at positionidx,falseotherwise.
Finds index of last occurrence of some value in this parallel iterable.
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.
- Type Params
- B
the type of the element
elem.
- Value Params
- elem
the element value to search for.
- Returns
the index of the last element of this parallel iterable that is equal (as determined by
==) toelem, or-1, if none exists.
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 before or at a given end index.
- Type Params
- B
the type of the element
elem.
- Value Params
- elem
the element value to search for.
- end
the end index.
- Returns
the index
<= endof the last element of this parallel iterable that is equal (as determined by==) toelem, or-1, if none exists.
Finds index of last element satisfying some predicate.
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.
- Value Params
- p
the predicate used to test elements.
- Returns
the index of the last element of this parallel iterable that satisfies the predicate
p, or-1, if none exists.
Finds the last element satisfying some predicate.
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.
- Value Params
- end
the maximum offset for the search
- p
the predicate used to test the elements
- Returns
the index
<= endof the first element of this parallel iterable that satisfies the predicatep, or-1, if none exists
Overload of ''patch'' that takes a sequential collection as parameter
Overload of ''patch'' that takes a sequential collection as parameter
Returns the length of the longest prefix whose elements all satisfy some predicate.
Returns the length of the longest prefix whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
- Value Params
- p
the predicate used to test elements.
- Returns
the length of the longest prefix of this parallel iterable such that every element of the segment satisfies the predicate
p.
Returns the length of the longest segment of elements starting at a given position satisfying some predicate.
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.
- Value Params
- from
the starting offset for the search
- p
the predicate used to test the elements
- Returns
the length of the longest segment of elements starting at
fromand satisfying the predicate
Tests whether this parallel iterable contains the given sequence at a given index.
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.
- Type Params
- S
the element type of
thatparallel sequence
- Value Params
- offset
the starting offset for the search
- that
the parallel sequence this sequence is being searched for
- Returns
trueif there is a sequencethatstarting atoffsetin this sequence,falseotherwise
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.
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.
- Type Params
- B
the element type of the returned parallel iterable.
- Value Params
- that
the sequence to add.
- Returns
a new parallel iterable which contains all elements of this parallel iterable followed by all elements of
that.
Inherited methods
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).
- Type Params
- S
the type of accumulated results
- Value Params
- combop
an associative operator used to combine results from different partitions
- seqop
an operator used to accumulate results within a partition
- z
the initial value for the accumulated result of the partition - this will typically be the neutral element for the
seqopoperator (e.g.Nilfor list concatenation or0for summation) and may be evaluated more than once
- Inherited from
- ParIterableLike
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.
- Value Params
- 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- Inherited from
- ParIterableLike
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.
- Value Params
- p
a predicate used to test elements
- Returns
true if
pholds for some element, false otherwise- Inherited from
- ParIterableLike
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.
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.
- Value Params
- p
predicate used to test the elements
- Returns
an option value with the element if such an element exists, or
Noneotherwise- Inherited from
- ParIterableLike
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.
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.
- Type Params
- U
a type parameter for the binary operator, a supertype of
T.
- Value Params
- op
a binary operator that must be associative
- 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.
Nilfor list concatenation, 0 for addition, or 1 for multiplication)
- Returns
the result of applying fold operator
opbetween all the elements andz- Inherited from
- ParIterableLike
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.
- Value Params
- p
a predicate used to test elements
- Returns
true if
pholds for all elements, false otherwise- Inherited from
- ParIterableLike
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.
- Type Params
- U
the result type of the function applied to each element, which is always discarded
- Value Params
- f
function applied to each element
- Inherited from
- ParIterableLike
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.
- Inherited from
- ParIterableLike
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.
- Type Params
- U
A type parameter for the binary operator, a supertype of
T.
- Value Params
- op
A binary operator that must be associative.
- Returns
The result of applying reduce operator
opbetween all the elements if the collection is nonempty.- Throws
- UnsupportedOperationException
if this parallel iterable is empty.
- Inherited from
- ParIterableLike
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.
- Type Params
- U
A type parameter for the binary operator, a supertype of
T.
- Value Params
- op
A binary operator that must be associative.
- Returns
An option value containing result of applying reduce operator
opbetween all the elements if the collection is nonempty, andNoneotherwise.- Inherited from
- ParIterableLike
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).
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).
- Value Params
- newc
The new, empty combiner that can be used.
- oldc
The combiner that is the result of the previous task, or
Noneif there was no previous task.
- Returns
Either
newcoroldc.- Inherited from
- ParIterableLike
Computes a prefix scan of the elements of the collection.
Computes a prefix scan of the elements of the collection.
Note: The neutral element z may be applied more than once.
- Type Params
- U
element type of the resulting collection
- Value Params
- op
the associative operator for the scan
- z
neutral element for the operator
op
- Returns
a new parallel iterable containing the prefix scan of the elements in this parallel iterable
- Inherited from
- ParIterableLike
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.
- Value Params
- 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- Inherited from
- ParIterableLike
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.
- Value Params
- pred
the predicate used to test the elements
- Returns
the longest prefix of this parallel iterable of elements that satisfy the predicate
pred- Inherited from
- ParIterableLike
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
- Inherited from
- ParIterableLike
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 java.util.concurrent.ForkJoinPool(2))
- See also
- Inherited from
- ParIterableLike
Zips this parallel iterable with its indices.
Zips this parallel iterable with its indices.
- Type Params
- U
the type of the first half of the returned pairs (this is always a supertype of the collection's element type
T).
- Returns
A new collection of type
ParIterablecontaining pairs consisting of all elements of this parallel iterable paired with their index. Indices start at 0.- Inherited from
- ParIterableLike
Deprecated and Inherited methods
Implicits
Inherited implicits
- Inherited from
- ParIterableLike