org.apache.commons.math3.stat.descriptive.summary
Class Product

java.lang.Object
  extended by org.apache.commons.math3.stat.descriptive.AbstractUnivariateStatistic
      extended by org.apache.commons.math3.stat.descriptive.AbstractStorelessUnivariateStatistic
          extended by org.apache.commons.math3.stat.descriptive.summary.Product
All Implemented Interfaces:
Serializable, StorelessUnivariateStatistic, UnivariateStatistic, WeightedEvaluation, MathArrays.Function

public class Product
extends AbstractStorelessUnivariateStatistic
implements Serializable, WeightedEvaluation

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.

Version:
$Id: Product.java 1416643 2012-12-03 19:37:14Z tn $
See Also:
Serialized Form

Constructor Summary
Product()
          Create a Product instance
Product(Product original)
          Copy constructor, creates a new Product identical to the original
 
Method Summary
 void clear()
          Clears the internal state of the Statistic
 Product copy()
          Returns a copy of the statistic with the same internal state.
static void copy(Product source, Product dest)
          Copies source to dest.
 double evaluate(double[] values, double[] weights)
          Returns the weighted product of the entries in the input array.
 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.apache.commons.math3.stat.descriptive.AbstractStorelessUnivariateStatistic
equals, evaluate, hashCode, incrementAll, incrementAll
 
Methods inherited from class org.apache.commons.math3.stat.descriptive.AbstractUnivariateStatistic
evaluate, getData, getDataRef, setData, setData, test, test, test, test
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 

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

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.

Throws MathIllegalArgumentException if the array is null.

Specified by:
evaluate in interface UnivariateStatistic
Specified by:
evaluate in interface MathArrays.Function
Overrides:
evaluate in class AbstractStorelessUnivariateStatistic
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:

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
Since:
2.1

evaluate

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

Returns the weighted product of the entries in the input array.

Throws MathIllegalArgumentException if any of the following are true:

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
Returns:
the product of the values or Double.NaN if length = 0
Throws:
MathIllegalArgumentException - if the parameters are not valid
Since:
2.1

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

copy

public static void copy(Product source,
                        Product dest)
                 throws NullArgumentException
Copies source to dest.

Neither source nor dest can be null.

Parameters:
source - Product to copy
dest - Product to copy to
Throws:
NullArgumentException - if either source or dest is null


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