org.hipparchus.stat.descriptive.summary

Class Product

java.lang.Object

org.hipparchus.stat.descriptive.AbstractStorelessUnivariateStatistic

org.hipparchus.stat.descriptive.summary.Product

All Implemented Interfaces:

Serializable, DoubleConsumer, AggregatableStatistic<Product>, StorelessUnivariateStatistic, UnivariateStatistic, WeightedEvaluation, MathArrays.Function

public class Product
extends AbstractStorelessUnivariateStatistic
implements AggregatableStatistic<Product>, WeightedEvaluation, Serializable

Returns the product of the available values.

If there are no values in the dataset, then 1 is returned. If any of the values are NaN, then NaN is returned.

Note that this implementation is not synchronized. If multiple threads access an instance of this class concurrently, and at least one of the threads invokes the increment() or clear() method, it must be synchronized externally.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
Product() Create a Product instance.
Product(Product original) Copy constructor, creates a new Product identical to the original.

Method Summary

Modifier and Type	Method and Description
void	aggregate(Product other) Aggregates the provided instance into this instance.
void	clear() Clears the internal state of the Statistic
Product	copy() Returns a copy of the statistic with the same internal state.
double	evaluate(double[] values, double[] weights, int begin, int length) Returns the weighted product of the entries in the specified portion of the input array, or Double.NaN if the designated subarray is empty.
double	evaluate(double[] values, int begin, int length) Returns the product of the entries in the specified portion of the input array, or Double.NaN if the designated subarray is empty.
long	getN() Returns the number of values that have been added.
double	getResult() Returns the current value of the Statistic.
void	increment(double d) Updates the internal state of the statistic to reflect the addition of the new value.

Methods inherited from class org.hipparchus.stat.descriptive.AbstractStorelessUnivariateStatistic

equals, hashCode, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.hipparchus.stat.descriptive.AggregatableStatistic

aggregate, aggregate

Methods inherited from interface org.hipparchus.stat.descriptive.WeightedEvaluation

evaluate

Methods inherited from interface org.hipparchus.stat.descriptive.StorelessUnivariateStatistic

accept, incrementAll, incrementAll

Methods inherited from interface org.hipparchus.stat.descriptive.UnivariateStatistic

evaluate

Methods inherited from interface java.util.function.DoubleConsumer

andThen

Constructor Detail

Product

public Product()

Create a Product instance.

Product

public Product(Product original)
        throws NullArgumentException

Copy constructor, creates a new Product identical to the original.

Parameters:

original - the Product instance to copy

Throws:

NullArgumentException - if original is null

Method Detail

increment

public void increment(double d)

Updates the internal state of the statistic to reflect the addition of the new value.

Specified by:

increment in interface StorelessUnivariateStatistic

Specified by:

increment in class AbstractStorelessUnivariateStatistic

Parameters:

d - the new value.

getResult

public double getResult()

Returns the current value of the Statistic.

Specified by:

getResult in interface StorelessUnivariateStatistic

Specified by:

getResult in class AbstractStorelessUnivariateStatistic

Returns:

value of the statistic, Double.NaN if it has been cleared or just instantiated.

getN

public long getN()

Returns the number of values that have been added.

Specified by:

getN in interface StorelessUnivariateStatistic

Returns:

the number of values.

clear

public void clear()

Clears the internal state of the Statistic

Specified by:

clear in interface StorelessUnivariateStatistic

Specified by:

clear in class AbstractStorelessUnivariateStatistic

aggregate

public void aggregate(Product other)

Aggregates the provided instance into this instance.

This method can be used to combine statistics computed over partitions or subsamples - i.e., the value of this instance after this operation should be the same as if a single statistic would have been applied over the combined dataset.

Specified by:

aggregate in interface AggregatableStatistic<Product>

Parameters:

other - the instance to aggregate into this instance

evaluate

public double evaluate(double[] values,
                       int begin,
                       int length)
                throws MathIllegalArgumentException

Returns the product of the entries in the specified portion of the input array, or Double.NaN if the designated subarray is empty.

Specified by:

evaluate in interface StorelessUnivariateStatistic

Specified by:

evaluate in interface UnivariateStatistic

Specified by:

evaluate in interface MathArrays.Function

Parameters:

values - the input array

begin - index of the first array element to include

length - the number of elements to include

Returns:

the product of the values or 1 if length = 0

Throws:

MathIllegalArgumentException - if the array is null or the array index parameters are not valid

See Also:

UnivariateStatistic.evaluate(double[], int, int)

evaluate

public double evaluate(double[] values,
                       double[] weights,
                       int begin,
                       int length)
                throws MathIllegalArgumentException

Returns the weighted product of the entries in the specified portion of the input array, or Double.NaN if the designated subarray is empty.

Throws MathIllegalArgumentException if any of the following are true:

• the values array is null
• the weights array is null
• the weights array does not have the same length as the values array
• the weights array contains one or more infinite values
• the weights array contains one or more NaN values
• the weights array contains negative values
• the start and length arguments do not determine a valid array

Uses the formula,

    weighted product = ∏values[i]weights[i]
 

that is, the weights are applied as exponents when computing the weighted product.

Specified by:

evaluate in interface WeightedEvaluation

Parameters:

values - the input array

weights - the weights array

begin - index of the first array element to include

length - the number of elements to include

Returns:

the product of the values or 1 if length = 0

Throws:

MathIllegalArgumentException - if the parameters are not valid

copy

public Product copy()

Returns a copy of the statistic with the same internal state.

Specified by:

copy in interface StorelessUnivariateStatistic

Specified by:

copy in interface UnivariateStatistic

Specified by:

copy in class AbstractStorelessUnivariateStatistic

Returns:

a copy of the statistic