jdk.util.stream.DoubleStream — clojure-interop/java.util.stream 1.0.5

A sequence of primitive double-valued elements supporting sequential and parallel aggregate operations. This is the double primitive specialization of Stream.

The following example illustrates an aggregate operation using Stream and DoubleStream, computing the sum of the weights of the red widgets:

double sum = widgets.stream()
                    .filter(w -> w.getColor() == RED)
                    .mapToDouble(w -> w.getWeight())
                    .sum();

See the class documentation for Stream and the package documentation for java.util.stream for additional specification of streams, stream operations, stream pipelines, and parallelism.

*builder clj

(*builder)

Returns a builder for a DoubleStream.

returns: a stream builder - java.util.stream.DoubleStream$Builder

*concat clj

(*concat a b)

Creates a lazily concatenated stream whose elements are all the elements of the first stream followed by all the elements of the second stream. The resulting stream is ordered if both of the input streams are ordered, and parallel if either of the input streams is parallel. When the resulting stream is closed, the close handlers for both input streams are invoked.

a - the first stream - java.util.stream.DoubleStream b - the second stream - java.util.stream.DoubleStream

returns: the concatenation of the two input streams - java.util.stream.DoubleStream

*empty clj

(*empty)

Returns an empty sequential DoubleStream.

returns: an empty sequential stream - java.util.stream.DoubleStream

*generate clj

(*generate s)

Returns an infinite sequential unordered stream where each element is generated by the provided DoubleSupplier. This is suitable for generating constant streams, streams of random elements, etc.

s - the DoubleSupplier for generated elements - java.util.function.DoubleSupplier

returns: a new infinite sequential unordered DoubleStream - java.util.stream.DoubleStream

*iterate clj

(*iterate seed f)

Returns an infinite sequential ordered DoubleStream produced by iterative application of a function f to an initial element seed, producing a Stream consisting of seed, f(seed), f(f(seed)), etc.

The first element (position 0) in the DoubleStream will be the provided seed. For n > 0, the element at position n, will be the result of applying the function f to the element at position n - 1.

seed - the initial element - double f - a function to be applied to to the previous element to produce a new element - java.util.function.DoubleUnaryOperator

returns: a new sequential DoubleStream - java.util.stream.DoubleStream

*of clj

(*of t)

Returns a sequential DoubleStream containing a single element.

t - the single element - double

returns: a singleton sequential stream - java.util.stream.DoubleStream

all-match clj

(all-match this predicate)

Returns whether all elements of this stream match the provided predicate. May not evaluate the predicate on all elements if not necessary for determining the result. If the stream is empty then true is returned and the predicate is not evaluated.

This is a short-circuiting terminal operation.

predicate - a non-interfering, stateless predicate to apply to elements of this stream - java.util.function.DoublePredicate

returns: true if either all elements of the stream match the provided predicate or the stream is empty, otherwise false - boolean

any-match clj

(any-match this predicate)

Returns whether any elements of this stream match the provided predicate. May not evaluate the predicate on all elements if not necessary for determining the result. If the stream is empty then false is returned and the predicate is not evaluated.

This is a short-circuiting terminal operation.

predicate - a non-interfering, stateless predicate to apply to elements of this stream - java.util.function.DoublePredicate

returns: true if any elements of the stream match the provided predicate, otherwise false - boolean

average clj

(average this)

Returns an OptionalDouble describing the arithmetic mean of elements of this stream, or an empty optional if this stream is empty.

If any recorded value is a NaN or the sum is at any point a NaN then the average will be NaN.

The average returned can vary depending upon the order in which values are recorded.

This method may be implemented using compensated summation or other technique to reduce the error bound in the numerical sum used to compute the average.

The average is a special case of a reduction.

This is a terminal operation.

returns: an OptionalDouble containing the average element of this stream, or an empty optional if the stream is empty - java.util.OptionalDouble

boxed clj

(boxed this)

Returns a Stream consisting of the elements of this stream, boxed to Double.

This is an intermediate operation.

returns: a Stream consistent of the elements of this stream, each boxed to a Double - java.util.stream.Stream<java.lang.Double>

collect clj

(collect this supplier accumulator combiner)

Performs a mutable reduction operation on the elements of this stream. A mutable reduction is one in which the reduced value is a mutable result container, such as an ArrayList, and elements are incorporated by updating the state of the result rather than by replacing the result. This produces a result equivalent to:

 R result = supplier.get();
 for (double element : this stream)
     accumulator.accept(result, element);
 return result;

Like reduce(double, DoubleBinaryOperator), collect operations can be parallelized without requiring additional synchronization.

This is a terminal operation.

supplier - a function that creates a new result container. For a parallel execution, this function may be called multiple times and must return a fresh value each time. - java.util.function.Supplier accumulator - an associative, non-interfering, stateless function for incorporating an additional element into a result - java.util.function.ObjDoubleConsumer combiner - an associative, non-interfering, stateless function for combining two values, which must be compatible with the accumulator function - java.util.function.BiConsumer

returns: the result of the reduction - <R> R

count clj

(count this)

Returns the count of elements in this stream. This is a special case of a reduction and is equivalent to:

 return mapToLong(e -> 1L).sum();

This is a terminal operation.

returns: the count of elements in this stream - long

distinct clj

(distinct this)

Returns a stream consisting of the distinct elements of this stream. The elements are compared for equality according to Double.compare(double, double).

This is a stateful intermediate operation.

returns: the result stream - java.util.stream.DoubleStream

filter clj

(filter this predicate)

Returns a stream consisting of the elements of this stream that match the given predicate.

This is an intermediate operation.

predicate - a non-interfering, stateless predicate to apply to each element to determine if it should be included - java.util.function.DoublePredicate

returns: the new stream - java.util.stream.DoubleStream

find-any clj

(find-any this)

Returns an OptionalDouble describing some element of the stream, or an empty OptionalDouble if the stream is empty.

This is a short-circuiting terminal operation.

The behavior of this operation is explicitly nondeterministic; it is free to select any element in the stream. This is to allow for maximal performance in parallel operations; the cost is that multiple invocations on the same source may not return the same result. (If a stable result is desired, use findFirst() instead.)

returns: an OptionalDouble describing some element of this stream, or an empty OptionalDouble if the stream is empty - java.util.OptionalDouble

find-first clj

(find-first this)

Returns an OptionalDouble describing the first element of this stream, or an empty OptionalDouble if the stream is empty. If the stream has no encounter order, then any element may be returned.

This is a short-circuiting terminal operation.

returns: an OptionalDouble describing the first element of this stream, or an empty OptionalDouble if the stream is empty - java.util.OptionalDouble

flat-map clj

(flat-map this mapper)

Returns a stream consisting of the results of replacing each element of this stream with the contents of a mapped stream produced by applying the provided mapping function to each element. Each mapped stream is closed after its contents have been placed into this stream. (If a mapped stream is null an empty stream is used, instead.)

This is an intermediate operation.

mapper - a non-interfering, stateless function to apply to each element which produces a DoubleStream of new values - java.util.function.DoubleFunction

returns: the new stream - java.util.stream.DoubleStream

for-each clj

(for-each this action)

Performs an action for each element of this stream.

This is a terminal operation.

For parallel stream pipelines, this operation does not guarantee to respect the encounter order of the stream, as doing so would sacrifice the benefit of parallelism. For any given element, the action may be performed at whatever time and in whatever thread the library chooses. If the action accesses shared state, it is responsible for providing the required synchronization.

action - a non-interfering action to perform on the elements - java.util.function.DoubleConsumer

for-each-ordered clj

(for-each-ordered this action)

Performs an action for each element of this stream, guaranteeing that each element is processed in encounter order for streams that have a defined encounter order.

This is a terminal operation.

action - a non-interfering action to perform on the elements - java.util.function.DoubleConsumer

iterator clj

(iterator this)

Description copied from interface: BaseStream

returns: the element iterator for this stream - java.util.PrimitiveIterator$OfDouble

limit clj

(limit this max-size)

Returns a stream consisting of the elements of this stream, truncated to be no longer than maxSize in length.

This is a short-circuiting stateful intermediate operation.

max-size - the number of elements the stream should be limited to - long

returns: the new stream - java.util.stream.DoubleStream

throws: java.lang.IllegalArgumentException - if maxSize is negative

map clj

(map this mapper)

Returns a stream consisting of the results of applying the given function to the elements of this stream.

This is an intermediate operation.

mapper - a non-interfering, stateless function to apply to each element - java.util.function.DoubleUnaryOperator

returns: the new stream - java.util.stream.DoubleStream

map-to-int clj

(map-to-int this mapper)

Returns an IntStream consisting of the results of applying the given function to the elements of this stream.

This is an intermediate operation.

mapper - a non-interfering, stateless function to apply to each element - java.util.function.DoubleToIntFunction

returns: the new stream - java.util.stream.IntStream

map-to-long clj

(map-to-long this mapper)

Returns a LongStream consisting of the results of applying the given function to the elements of this stream.

This is an intermediate operation.

mapper - a non-interfering, stateless function to apply to each element - java.util.function.DoubleToLongFunction

returns: the new stream - java.util.stream.LongStream

map-to-obj clj

(map-to-obj this mapper)

Returns an object-valued Stream consisting of the results of applying the given function to the elements of this stream.

This is an intermediate operation.

mapper - a non-interfering, stateless function to apply to each element - java.util.function.DoubleFunction

returns: the new stream - <U> java.util.stream.Stream<U>

max clj

(max this)

Returns an OptionalDouble describing the maximum element of this stream, or an empty OptionalDouble if this stream is empty. The maximum element will be Double.NaN if any stream element was NaN. Unlike the numerical comparison operators, this method considers negative zero to be strictly smaller than positive zero. This is a special case of a reduction and is equivalent to:

 return reduce(Double::max);

This is a terminal operation.

returns: an OptionalDouble containing the maximum element of this stream, or an empty optional if the stream is empty - java.util.OptionalDouble

min clj

(min this)

Returns an OptionalDouble describing the minimum element of this stream, or an empty OptionalDouble if this stream is empty. The minimum element will be Double.NaN if any stream element was NaN. Unlike the numerical comparison operators, this method considers negative zero to be strictly smaller than positive zero. This is a special case of a reduction and is equivalent to:

 return reduce(Double::min);

This is a terminal operation.

returns: an OptionalDouble containing the minimum element of this stream, or an empty optional if the stream is empty - java.util.OptionalDouble

none-match clj

(none-match this predicate)

Returns whether no elements of this stream match the provided predicate. May not evaluate the predicate on all elements if not necessary for determining the result. If the stream is empty then true is returned and the predicate is not evaluated.

This is a short-circuiting terminal operation.

predicate - a non-interfering, stateless predicate to apply to elements of this stream - java.util.function.DoublePredicate

returns: true if either no elements of the stream match the provided predicate or the stream is empty, otherwise false - boolean

parallel clj

(parallel this)

Description copied from interface: BaseStream

returns: a parallel stream - java.util.stream.DoubleStream

peek clj

(peek this action)

Returns a stream consisting of the elements of this stream, additionally performing the provided action on each element as elements are consumed from the resulting stream.

This is an intermediate operation.

For parallel stream pipelines, the action may be called at whatever time and in whatever thread the element is made available by the upstream operation. If the action modifies shared state, it is responsible for providing the required synchronization.

action - a non-interfering action to perform on the elements as they are consumed from the stream - java.util.function.DoubleConsumer

returns: the new stream - java.util.stream.DoubleStream

reduce clj

(reduce this op)

(reduce this identity op)

Performs a reduction on the elements of this stream, using the provided identity value and an associative accumulation function, and returns the reduced value. This is equivalent to:

 double result = identity;
 for (double element : this stream)
     result = accumulator.applyAsDouble(result, element)
 return result;

but is not constrained to execute sequentially.

The identity value must be an identity for the accumulator function. This means that for all x, accumulator.apply(identity, x) is equal to x. The accumulator function must be an associative function.

This is a terminal operation.

identity - the identity value for the accumulating function - double op - an associative, non-interfering, stateless function for combining two values - java.util.function.DoubleBinaryOperator

returns: the result of the reduction - double

sequential clj

(sequential this)

Description copied from interface: BaseStream

returns: a sequential stream - java.util.stream.DoubleStream

skip clj

(skip this n)

Returns a stream consisting of the remaining elements of this stream after discarding the first n elements of the stream. If this stream contains fewer than n elements then an empty stream will be returned.

This is a stateful intermediate operation.

n - the number of leading elements to skip - long

returns: the new stream - java.util.stream.DoubleStream

throws: java.lang.IllegalArgumentException - if n is negative

sorted clj

(sorted this)

Returns a stream consisting of the elements of this stream in sorted order. The elements are compared for equality according to Double.compare(double, double).

This is a stateful intermediate operation.

returns: the result stream - java.util.stream.DoubleStream

spliterator clj

(spliterator this)

Description copied from interface: BaseStream

returns: the element spliterator for this stream - java.util.Spliterator$OfDouble

sum clj

(sum this)

Returns the sum of elements in this stream.

Summation is a special case of a reduction. If floating-point summation were exact, this method would be equivalent to:

 return reduce(0, Double::sum);

However, since floating-point summation is not exact, the above code is not necessarily equivalent to the summation computation done by this method.

If any stream element is a NaN or the sum is at any point a NaN then the sum will be NaN.

The value of a floating-point sum is a function both of the input values as well as the order of addition operations. The order of addition operations of this method is intentionally not defined to allow for implementation flexibility to improve the speed and accuracy of the computed result.

In particular, this method may be implemented using compensated summation or other technique to reduce the error bound in the numerical sum compared to a simple summation of double values.

This is a terminal operation.

returns: the sum of elements in this stream - double

summary-statistics clj

(summary-statistics this)

Returns a DoubleSummaryStatistics describing various summary data about the elements of this stream. This is a special case of a reduction.

This is a terminal operation.

returns: a DoubleSummaryStatistics describing various summary data about the elements of this stream - java.util.DoubleSummaryStatistics

to-array clj

(to-array this)

Returns an array containing the elements of this stream.

This is a terminal operation.

returns: an array containing the elements of this stream - double[]