Package org.apache.commons.statistics.descriptive

Class LongMean

  • All Implemented Interfaces:
    DoubleSupplier, IntSupplier, LongConsumer, LongSupplier, LongStatistic, StatisticAccumulator<LongMean>, StatisticResult
    public final class LongMean
extends Object
implements LongStatistic, StatisticAccumulator<LongMean>
    Computes the arithmetic mean of the available values. Uses the following definition of the sample mean:

    \[ \frac{1}{n} \sum_{i=1}^n x_i \]

    where \( n \) is the number of samples.

    • The result is NaN if no values are added.

    This class uses an exact integer sum to compute the mean. Supports up to 263 (exclusive) observations. This implementation does not check for overflow of the count.

    This class is designed to work with (though does not require) streams.

    This implementation is not thread safe. If multiple threads access an instance of this class concurrently, and at least one of the threads invokes the accept or combine method, it must be synchronized externally.

    However, it is safe to use accept and combine as accumulator and combiner functions of Collector on a parallel stream, because the parallel implementation of Stream.collect() provides the necessary partitioning, isolation, and merging of results for safe and efficient parallel execution.

    Since:
    1.1

    • Method Detail

      • create

        public static LongMean create()
        Creates an instance.

        The initial result is NaN.

        Returns:
        IntMean instance.

      • of

        public static LongMean of​(long... values)
        Returns an instance populated using the input values.
        Parameters:
        values - Values.
        Returns:
        IntMean instance.

      • accept

        public void accept​(long value)
        Updates the state of the statistic to reflect the addition of value.
        Specified by:
        accept in interface LongConsumer
        Parameters:
        value - Value.

      • getAsDouble

        public double getAsDouble()
        Gets the mean of all input values.

        When no values have been added, the result is NaN.

        Specified by:
        getAsDouble in interface DoubleSupplier
        Returns:
        mean of all values.