java.util.stream.IntStream.mapToDouble()方法的使用及代码示例

x33g5p2x  于2022-01-20 转载在 其他  
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本文整理了Java中java.util.stream.IntStream.mapToDouble()方法的一些代码示例，展示了IntStream.mapToDouble()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。IntStream.mapToDouble()方法的具体详情如下：
包路径：java.util.stream.IntStream
类名称：IntStream
方法名：mapToDouble

IntStream.mapToDouble介绍

[英]Returns a DoubleStream consisting of the results of applying the given function to the elements of this stream.

This is an intermediate operation.
[中]返回一个DoubleStream，其中包含将给定函数应用于该流元素的结果。
这是一个intermediate operation。

代码示例

代码示例来源：origin: neo4j/neo4j

@SuppressWarnings( "unchecked" )
public static DoubleStream toDoubleStream( Object list )
{
  if ( list == null )
  {
    return DoubleStream.empty();
  }
  else if ( list instanceof SequenceValue )
  {
    throw new IllegalArgumentException( "Need to implement support for SequenceValue in CompiledConversionUtils.toDoubleStream" );
  }
  else if ( list instanceof List )
  {
    return ((List) list).stream().mapToDouble( n -> ((Number) n).doubleValue() );
  }
  else if ( Object[].class.isAssignableFrom( list.getClass() ) )
  {
    return Arrays.stream( (Object[]) list ).mapToDouble( n -> ((Number) n).doubleValue() );
  }
  else if ( list instanceof float[] )
  {
    float[] array = (float[]) list;
    return IntStream.range( 0, array.length ).mapToDouble( i -> array[i] );
  }
  else if ( list instanceof double[] )
  {
    return DoubleStream.of( (double[]) list );
  }
  throw new IllegalArgumentException( format( "Can not be converted to stream: %s", list.getClass().getName() ) );
}

代码示例来源：origin: spring-projects/spring-data-redis

/**
 * Creates equal {@link Weights} for a number of input sets {@code count} with a weight of one.
 *
 * @param count number of input sets. Must be greater or equal to zero.
 * @return equal {@link Weights} for a number of input sets with a weight of one.
 */
public static Weights fromSetCount(int count) {
  Assert.isTrue(count >= 0, "Count of input sorted sets must be greater or equal to zero!");
  return new Weights(IntStream.range(0, count).mapToDouble(value -> 1).boxed().collect(Collectors.toList()));
}

代码示例来源：origin: RichardWarburton/java-8-lambdas-exercises

public static double[] simpleMovingAverage(double[] values, int n) {
  double[] sums = Arrays.copyOf(values, values.length); // <1>
  Arrays.parallelPrefix(sums, Double::sum); // <2>
  int start = n - 1;
  return IntStream.range(start, sums.length) // <3>
          .mapToDouble(i -> {
            double prefix = i == start ? 0 : sums[i - n];
            return (sums[i] - prefix) / n; // <4>
          })
          .toArray(); // <5>
}
  // END simpleMovingAverage

代码示例来源：origin: apache/ignite

/**
 * Create {@link VectorGenerator} with vectors having feature values generated by random producer.
 *
 * @param vectorSize Generated vector size.
 * @return Vector generator.
 */
public default VectorGenerator vectorize(int vectorSize) {
  return () -> VectorUtils.of(IntStream.range(0, vectorSize).mapToDouble(x -> get()).toArray());
}

代码示例来源：origin: jtablesaw/tablesaw

private AttributeDataset dataset(NumericColumn<?> responseCol, AttributeType type, List<Column<?>> variableCols) {
  List<Column<?>> convertedVariableCols = variableCols.stream()
    .map(col -> col.type() == ColumnType.STRING ? col : table.nCol(col.name()))
    .collect(Collectors.toList());
  Attribute responseAttribute = type == AttributeType.NOMINAL
    ? colAsNominalAttribute(responseCol) : new NumericAttribute(responseCol.name());
  AttributeDataset dataset = new AttributeDataset(table.name(),
    convertedVariableCols.stream().map(col -> colAsAttribute(col)).toArray(Attribute[]::new),
    responseAttribute);
  for (int i = 0; i < responseCol.size(); i++) {
    final int r = i;
    double[] x = IntStream.range(0, convertedVariableCols.size())
      .mapToDouble(c -> getDouble(convertedVariableCols.get(c), dataset.attributes()[c], r))
      .toArray();
    dataset.add(x, responseCol.getDouble(r));
  }
  return dataset;
}

代码示例来源：origin: apache/nifi

return IntStream.range(0, floatArray.length)
    .mapToDouble(i -> floatArray[i])
    .mapToObj((element) -> convertToORCObject(TypeInfoFactory.getPrimitiveTypeInfo("float"), (float) element))
    .collect(Collectors.toList());
return IntStream.range(0, booleanArray.length)
    .map(i -> booleanArray[i] ? 1 : 0)
    .mapToObj((element) -> convertToORCObject(TypeInfoFactory.getPrimitiveTypeInfo("boolean"), element == 1))

代码示例来源：origin: apache/nifi

return IntStream.range(0, floatArray.length)
    .mapToDouble(i -> floatArray[i])
    .mapToObj((element) -> convertToORCObject(TypeInfoFactory.getPrimitiveTypeInfo("float"), (float) element, hiveFieldNames))
    .collect(Collectors.toList());
return IntStream.range(0, booleanArray.length)
    .map(i -> booleanArray[i] ? 1 : 0)
    .mapToObj((element) -> convertToORCObject(TypeInfoFactory.getPrimitiveTypeInfo("boolean"), element == 1, hiveFieldNames))

代码示例来源：origin: apache/tinkerpop

public static double clock(final int loops, final Runnable runnable) {
  runnable.run(); // warm-up
  return IntStream.range(0, loops).mapToDouble(i -> {
    long t = System.nanoTime();
    runnable.run();
    return (System.nanoTime() - t) * 0.000001;
  }).sum() / loops;
}

代码示例来源：origin: apache/tinkerpop

public static <S> Pair<Double, S> clockWithResult(final int loops, final Supplier<S> supplier) {
    final S result = supplier.get(); // warm up
    return Pair.with(IntStream.range(0, loops).mapToDouble(i -> {
      long t = System.nanoTime();
      supplier.get();
      return (System.nanoTime() - t) * 0.000001;
    }).sum() / loops, result);
  }
}

代码示例来源：origin: com.simiacryptus/mindseye-test

/**
 * Scan double stream.
 *
 * @return the double stream
 */
public DoubleStream scan() {
 return IntStream.range(-1000, 1000).mapToDouble(x -> x / 300.0);
}

代码示例来源：origin: com.simiacryptus/mindseye-research

/**
 * Dot double.
 *
 * @param a the a
 * @param b the b
 * @return the double
 */
public static double dot(double[] a, double[] b) {
 return IntStream.range(0, a.length).mapToDouble(i -> a[i] * b[i]).sum();
}

代码示例来源：origin: com.simiacryptus/mindseye

/**
 * Dot double.
 *
 * @param a the a
 * @param b the b
 * @return the double
 */
public static double dot(double[] a, double[] b) {
 return IntStream.range(0, a.length).mapToDouble(i -> a[i] * b[i]).sum();
}

代码示例来源：origin: org.apache.tinkerpop/gremlin-core

public static double clock(final int loops, final Runnable runnable) {
  runnable.run(); // warm-up
  return IntStream.range(0, loops).mapToDouble(i -> {
    long t = System.nanoTime();
    runnable.run();
    return (System.nanoTime() - t) * 0.000001;
  }).sum() / loops;
}

代码示例来源：origin: org.maochen.nlp/CoreNLP-NLP

private double[] reweight(final double[] x, final double[] weight, final double correctionD) {
  return IntStream.range(0, x.length)
      .mapToDouble(i -> weight[i] + model.learningRate * correctionD * x[i]) // Main Part, +1 strategy
      .toArray();
}

代码示例来源：origin: MegaMek/megamek

protected String getASRangeString(double[] damage) {
  return IntStream.range(0, damage.length).mapToDouble(i -> damage[i] / 10.0)
      .mapToObj(d -> {
        if (d > 0.5) {
          return Integer.toString((int)Math.round(d));
        } else if (d > 0) {
          return "0*";
        } else {
          return "0";
        }
      }).collect(Collectors.joining("/"));
}

代码示例来源：origin: jenetics/jenetics

/**
 * Returns a sequential stream of the alleles with this chromosome as its
 * source.
 *
 * @since 4.3
 *
 * @return a sequential stream of alleles
 */
public DoubleStream doubleStream() {
  return IntStream.range(0, length()).mapToDouble(this::doubleValue);
}

代码示例来源：origin: neo4j-contrib/neo4j-graph-algorithms

public double[] toArray() {
    return IntStream.range(0, capacity)
        .mapToDouble(this::get)
        .toArray();
  }
}

代码示例来源：origin: org.apache.tinkerpop/gremlin-core

public static <S> Pair<Double, S> clockWithResult(final int loops, final Supplier<S> supplier) {
    final S result = supplier.get(); // warm up
    return Pair.with(IntStream.range(0, loops).mapToDouble(i -> {
      long t = System.nanoTime();
      supplier.get();
      return (System.nanoTime() - t) * 0.000001;
    }).sum() / loops, result);
  }
}

代码示例来源：origin: com.simiacryptus/mindseye-research

/**
 * Add double [ ].
 *
 * @param a the a
 * @param b the b
 * @return the double [ ]
 */
public static double[] add(double[] a, double[] b) {
 return IntStream.range(0, a.length).mapToDouble(i -> a[i] + b[i]).toArray();
}

代码示例来源：origin: com.simiacryptus/mindseye-research

/**
 * Dot double.
 *
 * @param a the a
 * @param b the b
 * @return the double
 */
public static double dot(@Nonnull final List<DoubleBuffer<UUID>> a, @Nonnull final List<DoubleBuffer<UUID>> b) {
 assert a.size() == b.size();
 return IntStream.range(0, a.size()).mapToDouble(i -> a.get(i).dot(b.get(i))).sum();
}

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