Package org.apache.commons.statistics.descriptive

Class LongMean

java.lang.Object

org.apache.commons.statistics.descriptive.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 Summary

Modifier and Type	Method	Description
void	accept(long value)	Updates the state of the statistic to reflect the addition of value.
LongMean	combine(LongMean other)	Combines the state of the other statistic into this one.
static LongMean	create()	Creates an instance.
double	getAsDouble()	Gets the mean of all input values.
static LongMean	of(long... values)	Returns an instance populated using the input values.
static LongMean	ofRange(long[] values, int from, int to)	Returns an instance populated using the specified range of values.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.function.LongConsumer

andThen

Methods inherited from interface org.apache.commons.statistics.descriptive.StatisticResult

getAsBigInteger, getAsInt, getAsLong

Method Detail

create

public static LongMean create()

Creates an instance.

The initial result is NaN.

Returns:

LongMean instance.

of

public static LongMean of(long... values)

Returns an instance populated using the input values.

Parameters:

values - Values.

Returns:

LongMean instance.

ofRange

public static LongMean ofRange(long[] values,
                               int from,
                               int to)

Returns an instance populated using the specified range of values.

Parameters:

values - Values.

from - Inclusive start of the range.

to - Exclusive end of the range.

Returns:

LongMean instance.

Throws:

IndexOutOfBoundsException - if the sub-range is out of bounds

Since:

1.2

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.

combine

public LongMean combine(LongMean other)

Description copied from interface: StatisticAccumulator

Combines the state of the other statistic into this one.

Specified by:

combine in interface StatisticAccumulator<LongMean>

Parameters:

other - Another statistic to be combined.

Returns:

this instance after combining other.