Class GeometricMean
- java.lang.Object
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- org.apache.commons.math4.legacy.stat.descriptive.AbstractStorelessUnivariateStatistic
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- org.apache.commons.math4.legacy.stat.descriptive.moment.GeometricMean
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- All Implemented Interfaces:
MathArrays.Function,StorelessUnivariateStatistic,UnivariateStatistic
public class GeometricMean extends AbstractStorelessUnivariateStatistic
Returns the geometric mean of the available values.Uses a
SumOfLogsinstance to compute sum of logs and returnsexp( 1/n (sum of logs) ).Therefore,- If any of values are
< 0, the result isNaN. - If all values are non-negative and less than
Double.POSITIVE_INFINITY, but at least one value is 0, the result is0. - If both
Double.POSITIVE_INFINITYandDouble.NEGATIVE_INFINITYare among the values, the result isNaN.
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()orclear()method, it must be synchronized externally.
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Constructor Summary
Constructors Constructor Description GeometricMean()Create a GeometricMean instance.GeometricMean(GeometricMean original)Copy constructor, creates a newGeometricMeanidentical to theoriginal.GeometricMean(SumOfLogs sumOfLogs)Create a GeometricMean instance using the given SumOfLogs instance.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description voidclear()Clears the internal state of the Statistic.GeometricMeancopy()Returns a copy of the statistic with the same internal state.static voidcopy(GeometricMean source, GeometricMean dest)Copies source to dest.doubleevaluate(double[] values, int begin, int length)Returns the geometric mean of the entries in the specified portion of the input array.longgetN()Returns the number of values that have been added.doublegetResult()Returns the current value of the Statistic.StorelessUnivariateStatisticgetSumLogImpl()Returns the currently configured sum of logs implementation.voidincrement(double d)Updates the internal state of the statistic to reflect the addition of the new value.voidsetSumLogImpl(StorelessUnivariateStatistic sumLogImpl)Sets the implementation for the sum of logs.-
Methods inherited from class org.apache.commons.math4.legacy.stat.descriptive.AbstractStorelessUnivariateStatistic
equals, evaluate, hashCode, incrementAll, incrementAll
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Constructor Detail
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GeometricMean
public GeometricMean()
Create a GeometricMean instance.
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GeometricMean
public GeometricMean(GeometricMean original) throws NullArgumentException
Copy constructor, creates a newGeometricMeanidentical to theoriginal.- Parameters:
original- theGeometricMeaninstance to copy- Throws:
NullArgumentException- if original is null
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GeometricMean
public GeometricMean(SumOfLogs sumOfLogs)
Create a GeometricMean instance using the given SumOfLogs instance.- Parameters:
sumOfLogs- sum of logs instance to use for computation.
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Method Detail
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copy
public GeometricMean copy()
Returns a copy of the statistic with the same internal state.- Specified by:
copyin interfaceStorelessUnivariateStatistic- Specified by:
copyin interfaceUnivariateStatistic- Specified by:
copyin classAbstractStorelessUnivariateStatistic- Returns:
- a copy of the statistic
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increment
public void increment(double d)
Updates the internal state of the statistic to reflect the addition of the new value.- Specified by:
incrementin interfaceStorelessUnivariateStatistic- Specified by:
incrementin classAbstractStorelessUnivariateStatistic- Parameters:
d- the new value.
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getResult
public double getResult()
Returns the current value of the Statistic.- Specified by:
getResultin interfaceStorelessUnivariateStatistic- Specified by:
getResultin classAbstractStorelessUnivariateStatistic- Returns:
- value of the statistic,
Double.NaNif it has been cleared or just instantiated.
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clear
public void clear()
Clears the internal state of the Statistic.- Specified by:
clearin interfaceStorelessUnivariateStatistic- Specified by:
clearin classAbstractStorelessUnivariateStatistic
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evaluate
public double evaluate(double[] values, int begin, int length) throws MathIllegalArgumentException
Returns the geometric mean of the entries in the specified portion of the input array.See
GeometricMeanfor details on the computing algorithm.Throws
IllegalArgumentExceptionif the array is null.- Specified by:
evaluatein interfaceMathArrays.Function- Specified by:
evaluatein interfaceUnivariateStatistic- Overrides:
evaluatein classAbstractStorelessUnivariateStatistic- Parameters:
values- input array containing the valuesbegin- first array element to includelength- the number of elements to include- Returns:
- the geometric mean or Double.NaN if length = 0 or any of the values are <= 0.
- Throws:
MathIllegalArgumentException- if the input array is null or the array index parameters are not valid- See Also:
UnivariateStatistic.evaluate(double[], int, int)
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getN
public long getN()
Returns the number of values that have been added.- Returns:
- the number of values.
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setSumLogImpl
public void setSumLogImpl(StorelessUnivariateStatistic sumLogImpl) throws MathIllegalStateException
Sets the implementation for the sum of logs.
This method must be activated before any data has been added - i.e., before
incrementhas been used to add data; otherwise an IllegalStateException will be thrown.- Parameters:
sumLogImpl- the StorelessUnivariateStatistic instance to use for computing the log sum- Throws:
MathIllegalStateException- if data has already been added (i.e if n > 0)
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getSumLogImpl
public StorelessUnivariateStatistic getSumLogImpl()
Returns the currently configured sum of logs implementation.- Returns:
- the StorelessUnivariateStatistic implementing the log sum
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copy
public static void copy(GeometricMean source, GeometricMean dest) throws NullArgumentException
Copies source to dest.Neither source nor dest can be null.
- Parameters:
source- GeometricMean to copydest- GeometricMean to copy to- Throws:
NullArgumentException- if either source or dest is null
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