java.util.PrimitiveIterator.OfDouble Java Examples

@Override
public OfDouble iterator() {
  return new OfDouble() {
    int i = 0;
    
    @Override
    public boolean hasNext() {
      return i < size();
    }

    @Override
    public Double next() {
      if (!hasNext())
        throw new NoSuchElementException();
      return get(i++);
    }

    @Override
    public double nextDouble() {
      if (!hasNext())
        throw new NoSuchElementException();
      return get(i++);
    }
  };
}
 

@Override
public Iterable<Double> filter(DoubleSet similarities) {
	if (similarities.isEmpty()) {
		return DoubleSets.EMPTY_SET;
	}
	DoubleSortedSet filtered = sorted(similarities);
	double first = filtered.firstDouble();
	int intervals = size - 1;
	if (intervals == 0) {
		return DoubleSets.singleton(first);
	}
	double last = filtered.lastDouble();
	double intervalSize = (first - last) / intervals;
	UniformTrimmer trimmer = new UniformTrimmer(intervalSize);
	OfDouble iterator = filtered.iterator();
	trimmer.trim(iterator);
	return filtered;
}
 

/**
 * Returns a {@code float[]} array containing the elements of this stream
 * which are converted to floats using {@code (float)} cast operation.
 *
 * <p>
 * This is a terminal operation.
 *
 * @return an array containing the elements of this stream
 * @since 0.3.0
 */
public float[] toFloatArray() {
    if (isParallel())
        return collect(DoubleCollector.toFloatArray());
    java.util.Spliterator.OfDouble spliterator = spliterator();
    int size = intSize(spliterator);
    FloatBuffer buf;
    if (size >= 0) {
        buf = new FloatBuffer(size);
        spliterator.forEachRemaining((DoubleConsumer) buf::addUnsafe);
    } else {
        buf = new FloatBuffer();
        spliterator.forEachRemaining((DoubleConsumer) buf::add);
    }
    return buf.toArray();
}
 

public static OptionalDouble next(OfDouble it) {
	if (it.hasNext()) {
		double higher = it.nextDouble();
		return OptionalDouble.of(higher);
	}
	return OptionalDouble.empty();
}
 

@Test
public void testDropWhile() {
    assertArrayEquals(new double[] { 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 }, LongStreamEx.range(100).asDoubleStream()
            .dropWhile(i -> i % 10 < 5).limit(10).toArray(), 0.0);
    assertEquals(100, LongStreamEx.range(100).asDoubleStream().sorted().dropWhile(i -> i % 10 < 0).count());
    assertEquals(0, LongStreamEx.range(100).asDoubleStream().dropWhile(i -> i % 10 < 10).count());
    assertEquals(OptionalDouble.of(0), LongStreamEx.range(100).asDoubleStream().dropWhile(i -> i % 10 < 0).findFirst());
    assertEquals(OptionalDouble.empty(), LongStreamEx.range(100).asDoubleStream().dropWhile(i -> i % 10 < 10).findFirst());

    java.util.Spliterator.OfDouble spltr = LongStreamEx.range(100).asDoubleStream().dropWhile(i -> i % 10 < 1).spliterator();
    assertTrue(spltr.tryAdvance((double x) -> assertEquals(1, x, 0.0)));
    Builder builder = DoubleStream.builder();
    spltr.forEachRemaining(builder);
    assertArrayEquals(LongStreamEx.range(2, 100).asDoubleStream().toArray(), builder.build().toArray(), 0.0);
}
 

private void trim(OfDouble iterator) {
	while (iterator.hasNext()) {
		double current = iterator.nextDouble();
		if (current <= first - count * intervalSize) {
			double diff = first - current;
			count = Math.max(count, (int) (diff / intervalSize)) + 1;
		} else {
			iterator.remove();
		}
	}
}
 

@Test
public void testNextDouble() {
	DoubleList list = DoubleLists.singleton(1.0);
	OfDouble it = list.iterator();
	assertThat(IteratorUtils.next(it).boxed()).hasValue(1.0);
	assertThat(IteratorUtils.next(it).boxed()).isEmpty();
}
 

private static Dimension toDimension(DoubleSortedSet thresholds) {
	int size = thresholds.size();
	Double2IntMap map = new Double2IntOpenHashMap(size);
	int i = 1;
	OfDouble it = thresholds.iterator();
	while (it.hasNext()) {
		double threshold = it.nextDouble();
		map.put(threshold, i++);
	}
	return new Dimension(map);
}
 

DoubleStreamEx(Spliterator.OfDouble spliterator, StreamContext context) {
    super(spliterator, context);
}
 

final DoubleStreamEx delegate(Spliterator.OfDouble spliterator) {
    return new DoubleStreamEx(spliterator, context);
}
 

public void trim(OfDouble iterator) {
	OptionalDouble first = IteratorUtils.next(iterator);
	first.map(this::with)
		.ifPresent(w -> w.trim(iterator));
}
 

@Override
public OfDouble iterator() {
    return Spliterators.iterator(spliterator());
}
 

@Test
public void testBasics() {
    assertFalse(DoubleStreamEx.of(1).isParallel());
    assertTrue(DoubleStreamEx.of(1).parallel().isParallel());
    assertFalse(DoubleStreamEx.of(1).parallel().sequential().isParallel());
    AtomicInteger i = new AtomicInteger();
    try (DoubleStreamEx s = DoubleStreamEx.of(1).onClose(i::incrementAndGet)) {
        assertEquals(1, s.count());
    }
    assertEquals(1, i.get());
    assertEquals(6, IntStreamEx.range(0, 4).asDoubleStream().sum(), 0);
    assertEquals(3, IntStreamEx.range(0, 4).asDoubleStream().max().getAsDouble(), 0);
    assertEquals(0, IntStreamEx.range(0, 4).asDoubleStream().min().getAsDouble(), 0);
    assertEquals(1.5, IntStreamEx.range(0, 4).asDoubleStream().average().getAsDouble(), 0.000001);
    assertEquals(4, IntStreamEx.range(0, 4).asDoubleStream().summaryStatistics().getCount());
    assertArrayEquals(new double[] { 1, 2, 3 },
        IntStreamEx.range(0, 5).asDoubleStream().skip(1).limit(3).toArray(), 0.0);
    assertArrayEquals(new double[] { 1, 2, 3 }, DoubleStreamEx.of(3, 1, 2).sorted().toArray(), 0.0);
    assertArrayEquals(new double[] { 1, 2, 3 }, DoubleStreamEx.of(1, 2, 1, 3, 2).distinct().toArray(), 0.0);
    assertArrayEquals(new int[] { 2, 4, 6 }, IntStreamEx.range(1, 4).asDoubleStream().mapToInt(x -> (int) x * 2)
            .toArray());
    assertArrayEquals(new long[] { 2, 4, 6 }, IntStreamEx.range(1, 4).asDoubleStream().mapToLong(x -> (long) x * 2)
            .toArray());
    assertArrayEquals(new double[] { 2, 4, 6 }, IntStreamEx.range(1, 4).asDoubleStream().map(x -> x * 2).toArray(),
        0.0);
    assertArrayEquals(new double[] { 1, 3 }, IntStreamEx.range(0, 5).asDoubleStream().filter(x -> x % 2 == 1)
            .toArray(), 0.0);
    assertEquals(6.0, DoubleStreamEx.of(1.0, 2.0, 3.0).reduce(Double::sum).getAsDouble(), 0.0);
    assertEquals(Long.MAX_VALUE, LongStreamEx.rangeClosed(1, Long.MAX_VALUE).asDoubleStream().spliterator()
            .getExactSizeIfKnown());

    assertArrayEquals(new double[] { 4, 2, 0, -2, -4 }, DoubleStreamEx.zip(new double[] { 5, 4, 3, 2, 1 },
        new double[] { 1, 2, 3, 4, 5 }, (a, b) -> a - b).toArray(), 0.0);
    assertEquals("1.0; 0.5; 0.25; 0.125", DoubleStreamEx.of(1.0, 0.5, 0.25, 0.125).mapToObj(String::valueOf)
            .joining("; "));
    List<Double> list = new ArrayList<>();
    DoubleStreamEx.of(1.0, 0.5, 0.25, 0.125).forEach(list::add);
    assertEquals(Arrays.asList(1.0, 0.5, 0.25, 0.125), list);
    list = new ArrayList<>();
    DoubleStreamEx.of(1.0, 0.5, 0.25, 0.125).parallel().forEachOrdered(list::add);
    assertEquals(Arrays.asList(1.0, 0.5, 0.25, 0.125), list);

    assertFalse(DoubleStreamEx.of(1.0, 2.0, 2.5).anyMatch(x -> x < 0.0));
    assertTrue(DoubleStreamEx.of(1.0, 2.0, 2.5).anyMatch(x -> x >= 2.5));
    assertTrue(DoubleStreamEx.of(1.0, 2.0, 2.5).noneMatch(x -> x < 0.0));
    assertFalse(DoubleStreamEx.of(1.0, 2.0, 2.5).noneMatch(x -> x >= 2.5));
    assertEquals(5.0, DoubleStreamEx.of(1.0, 2.0, 2.5).reduce(1, (a, b) -> a * b), 0.0);

    assertTrue(DoubleStreamEx.of(1, 2, 3).spliterator().hasCharacteristics(Spliterator.ORDERED));
    assertFalse(DoubleStreamEx.of(1, 2, 3).unordered().spliterator().hasCharacteristics(Spliterator.ORDERED));

    OfDouble iterator = DoubleStreamEx.of(1.0, 2.0, 3.0).iterator();
    assertEquals(1.0, iterator.next(), 0.0);
    assertEquals(2.0, iterator.next(), 0.0);
    assertEquals(3.0, iterator.next(), 0.0);
    assertFalse(iterator.hasNext());
}
 

@Override
public Spliterator.OfDouble spliterator() {
  return Arrays.spliterator(theArray);
}
 

/**
 * Produces an array containing cumulative results of applying the
 * accumulation function going left to right.
 * 
 * <p>
 * This is a terminal operation.
 * 
 * <p>
 * For parallel stream it's not guaranteed that accumulator will always be
 * executed in the same thread.
 * 
 * <p>
 * This method cannot take all the advantages of parallel streams as it must
 * process elements strictly left to right.
 *
 * @param accumulator a
 *        <a href="package-summary.html#NonInterference">non-interfering
 *        </a>, <a href="package-summary.html#Statelessness">stateless</a>
 *        function for incorporating an additional element into a result
 * @return the array where the first element is the first element of this
 *         stream and every successor element is the result of applying
 *         accumulator function to the previous array element and the
 *         corresponding stream element. The resulting array has the same
 *         length as this stream.
 * @see #foldLeft(DoubleBinaryOperator)
 * @since 0.5.1
 */
public double[] scanLeft(DoubleBinaryOperator accumulator) {
    Spliterator.OfDouble spliterator = spliterator();
    int size = intSize(spliterator);
    DoubleBuffer buf = new DoubleBuffer(size == -1 ? INITIAL_SIZE : size);
    delegate(spliterator).forEachOrdered(i -> buf.add(buf.size == 0 ? i
            : accumulator.applyAsDouble(buf.data[buf.size - 1], i)));
    return buf.toArray();
}
 

/**
 * Returns a stream containing cumulative results of applying the
 * accumulation function going left to right.
 * 
 * <p>
 * This is a stateful
 * <a href="package-summary.html#StreamOps">quasi-intermediate</a>
 * operation.
 *
 * <p>
 * This operation resembles {@link #scanLeft(DoubleBinaryOperator)}, but
 * unlike {@code scanLeft} this operation is intermediate and accumulation
 * function must be associative.
 * 
 * <p>
 * This method cannot take all the advantages of parallel streams as it must
 * process elements strictly left to right. Using an unordered source or
 * removing the ordering constraint with {@link #unordered()} may improve
 * the parallel processing speed.
 *
 * @param op an <a href="package-summary.html#Associativity">associative</a>
 *        , <a href="package-summary.html#NonInterference">non-interfering
 *        </a>, <a href="package-summary.html#Statelessness">stateless</a>
 *        function for computing the next element based on the previous one
 * @return the new stream.
 * @see #scanLeft(DoubleBinaryOperator)
 * @since 0.6.1
 */
public DoubleStreamEx prefix(DoubleBinaryOperator op) {
    return delegate(new PrefixOps.OfDouble(spliterator(), op));
}
 

/**
 * Returns a sequential {@code DoubleStreamEx} containing a single element.
 *
 * @param element the single element
 * @return a singleton sequential stream
 */
public static DoubleStreamEx of(double element) {
    return of(new ConstSpliterator.OfDouble(element, 1, true));
}
 

/**
 * Returns a sequential {@link DoubleStreamEx} created from given
 * {@link java.util.Spliterator.OfDouble}.
 * 
 * @param spliterator a spliterator to create the stream from.
 * @return the new stream
 * @since 0.3.4
 */
public static DoubleStreamEx of(Spliterator.OfDouble spliterator) {
    return new DoubleStreamEx(spliterator, StreamContext.SEQUENTIAL);
}
 

/**
 * Returns a sequential, ordered {@link DoubleStreamEx} created from given
 * {@link java.util.PrimitiveIterator.OfDouble}.
 *
 * <p>
 * This method is roughly equivalent to
 * {@code DoubleStreamEx.of(Spliterators.spliteratorUnknownSize(iterator, ORDERED))}
 * , but may show better performance for parallel processing.
 * 
 * <p>
 * Use this method only if you cannot provide better Stream source.
 *
 * @param iterator an iterator to create the stream from.
 * @return the new stream
 * @since 0.5.1
 */
public static DoubleStreamEx of(PrimitiveIterator.OfDouble iterator) {
    return of(new UnknownSizeSpliterator.USOfDouble(iterator));
}
 

/**
 * Returns a sequential unordered {@code DoubleStreamEx} of given length
 * which elements are equal to supplied value.
 * 
 * @param value the constant value
 * @param length the length of the stream
 * @return a new {@code DoubleStreamEx}
 * @since 0.1.2
 */
public static DoubleStreamEx constant(double value, long length) {
    return of(new ConstSpliterator.OfDouble(value, length, false));
}
 

/**
 * Returns the spliterator which covers all the elements emitted by this
 * emitter.
 * 
 * @return the new spliterator
 */
default Spliterator.OfDouble spliterator() {
    return new EmitterSpliterator.OfDouble(this);
}