Java PrimitiveIterator.OfDouble方法代碼示例

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
/**
 * Returns an infinite sequential ordered {@code DoubleStream} produced by iterative
 * application of a function {@code f} to an initial element {@code seed},
 * producing a {@code Stream} consisting of {@code seed}, {@code f(seed)},
 * {@code f(f(seed))}, etc.
 *
 * <p>The first element (position {@code 0}) in the {@code DoubleStream}
 * will be the provided {@code seed}.  For {@code n > 0}, the element at
 * position {@code n}, will be the result of applying the function {@code f}
 *  to the element at position {@code n - 1}.
 *
 * @param seed the initial element
 * @param f a function to be applied to to the previous element to produce
 *          a new element
 * @return a new sequential {@code DoubleStream}
 */
public static DoubleStream iterate(final double seed, final DoubleUnaryOperator f) {
    Objects.requireNonNull(f);
    final PrimitiveIterator.OfDouble iterator = new PrimitiveIterator.OfDouble() {
        double t = seed;

        @Override
        public boolean hasNext() {
            return true;
        }

        @Override
        public double nextDouble() {
            double v = t;
            t = f.applyAsDouble(t);
            return v;
        }
    };
    return StreamSupport.doubleStream(Spliterators.spliteratorUnknownSize(
            iterator,
            Spliterator.ORDERED | Spliterator.IMMUTABLE | Spliterator.NONNULL), false);
}
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
/**
 * Returns a primitive iterator for this range
 * @return  the primitive iterator
 */
private PrimitiveIterator.OfDouble iteratorOfDouble() {
    return new PrimitiveIterator.OfDouble() {
        private double value = start;
        @Override
        public boolean hasNext() {
            if (excludes != null) {
                while (excludes.test(value) && inBounds(value)) {
                    value = ascend ? value + step : value - step;
                }
            }
            return inBounds(value);
        }
        @Override
        public double nextDouble() {
            final double next = value;
            value = ascend ? value + step : value - step;
            return next;
        }
    };
}
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
public void testDoubleForEachRemainingWithNull() {
    PrimitiveIterator.OfDouble i = new PrimitiveIterator.OfDouble() {
        @Override
        public double nextDouble() {
            return 0;
        }

        @Override
        public boolean hasNext() {
            return false;
        }
    };

    executeAndCatch(() -> i.forEachRemaining((DoubleConsumer) null));
    executeAndCatch(() -> i.forEachRemaining((Consumer<Double>) null));
}
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
public void testDoubleForEachRemainingWithNull() {
    PrimitiveIterator.OfDouble i = new PrimitiveIterator.OfDouble() {
        @Override
        public double nextDouble() {
            return 0;
        }

        @Override
        public boolean hasNext() {
            return false;
        }
    };

    assertThrowsNPE(() -> i.forEachRemaining((DoubleConsumer) null));
    assertThrowsNPE(() -> i.forEachRemaining((Consumer<Double>) null));
}
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
/** {@inheritDoc} */
@Override public VarianceData calculateRegionInfo(DoubleStream s, int size) {
    PrimitiveIterator.OfDouble itr = s.iterator();
    int i = 0;

    double mean = 0.0;
    double m2 = 0.0;

    // Here we calculate variance and mean by incremental computation.
    while (itr.hasNext()) {
        i++;
        double x = itr.next();
        double delta = x - mean;
        mean += delta / i;
        double delta2 = x - mean;
        m2 += delta * delta2;
    }

    return new VarianceData(m2 / i, size, mean);
}
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
public PrimitiveIterator.OfDouble rowMajor() {
  return new PrimitiveIterator.OfDouble() {
    int idx = 0;

    public boolean hasNext() {
      return idx < 16;
    }

    public double nextDouble() {
      if (idx < 9) {
        return elements[idx++];
      } else {
        throw new NoSuchElementException();
      }
    }
  };
}
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
public PrimitiveIterator.OfDouble rowMajor() {
  return new PrimitiveIterator.OfDouble() {
    int idx = 0;

    public boolean hasNext() {
      return idx < 9;
    }

    public double nextDouble() {
      if (idx < 9) {
        return elements[idx++];
      } else {
        throw new NoSuchElementException();
      }
    }
  };
}
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
private Node.OfDouble degenerateTree(PrimitiveIterator.OfDouble it) {
    if (!it.hasNext()) {
        return Nodes.node(new double[0]);
    }

    double i = it.nextDouble();
    if (it.hasNext()) {
        return new Nodes.ConcNode.OfDouble(Nodes.node(new double[] {i}), degenerateTree(it));
    }
    else {
        return Nodes.node(new double[] {i});
    }
}
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
@Override
public final PrimitiveIterator.OfDouble iterator() {
    return Spliterators.iterator(spliterator());
}
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
@Override
public PrimitiveIterator.OfDouble iterator() {
    return Spliterators.iterator(spliterator());
}
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
@Override
PrimitiveIterator.OfDouble iterator();
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
@Override
public PrimitiveIterator.OfDouble iterator() {
    return s.iterator();
}
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
/** {@inheritDoc} */
@Override public GiniData calculateRegionInfo(DoubleStream s, int l) {
    PrimitiveIterator.OfDouble itr = s.iterator();

    Map<Double, Integer> m = new HashMap<>();

    int size = 0;

    while (itr.hasNext()) {
        size++;
        m.compute(itr.next(), (a, i) -> i != null ? i + 1 : 1);
    }

    double c2 = m.values().stream().mapToDouble(v -> v * v).sum();

    int[] cnts = new int[mapping.size()];

    m.forEach((key, value) -> cnts[mapping.get(key)] = value);

    return new GiniData(size != 0 ? 1 - c2 / (size * size) : 0.0, size, cnts, c2);
}
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
public PrimitiveIterator.OfDouble columnMajor() {
  return transpose().rowMajor();
}
 

import java.util.PrimitiveIterator; //導入方法依賴的package包/類
@Override
public PrimitiveIterator.OfDouble execute() {
    try (final DoubleStream stream = buildPrevious()) {
        return stream.iterator();
    }
}