Example usage for java.util.stream DoubleStream average

Introduction

In this page you can find the example usage for java.util.stream DoubleStream average.

Prototype

OptionalDouble average();

Source Link

Document

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

Usage

From source file:Main.java

public static void main(String[] args) {
    DoubleStream d = DoubleStream.of(1.2, 2.3, 4.5);

    OptionalDouble v = d.average();

    if (v.isPresent()) {
        System.out.println(v.getAsDouble());
    } else {// w  w  w  . j a  va  2 s.  c om
        System.out.println("no value");
    }
}

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From source file:com.hortonworks.streamline.streams.metrics.storm.ambari.AmbariMetricsServiceWithStormQuerier.java

private Map<Long, Double> aggregateStreamsForMetricsValues(Map<Long, List<Pair<String, Double>>> ret,
        AggregateFunction aggrFunction) {
    return ret.entrySet().stream().collect(toMap(e -> e.getKey(), e -> {
        DoubleStream valueStream = e.getValue().stream().mapToDouble(d -> d.getRight());
        switch (aggrFunction) {
        case SUM:
            return valueStream.sum();

        case AVG:
            return valueStream.average().orElse(0.0d);

        case MAX:
            return valueStream.max().orElse(0.0d);

        case MIN:
            return valueStream.min().orElse(0.0d);

        default:/*  w w  w  . java 2 s  . co m*/
            throw new IllegalArgumentException("Not supported aggregated function.");

        }
    }));
}

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