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java.lang.Objectorg.apache.commons.math.stat.descriptive.AbstractUnivariateStatistic
org.apache.commons.math.stat.descriptive.AbstractStorelessUnivariateStatistic
org.apache.commons.math.stat.descriptive.moment.GeometricMean
public class GeometricMean
Returns the geometric mean of the available values.
Uses a SumOfLogs
instance to compute sum of logs and returns
exp( 1/n (sum of logs) ).
Therefore,
NaN.
Double.POSITIVE_INFINITY
, but at least one value is 0, the
result is 0.
Double.POSITIVE_INFINITY
and
Double.NEGATIVE_INFINITY
are among the values, the result is
NaN.
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.
Field Summary | |
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private static long |
serialVersionUID
Serializable version identifier |
private StorelessUnivariateStatistic |
sumOfLogs
Wrapped SumOfLogs instance |
Constructor Summary | |
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GeometricMean()
Create a GeometricMean instance |
|
GeometricMean(SumOfLogs sumOfLogs)
Create a GeometricMean instance using the given SumOfLogs instance |
Method Summary | |
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private void |
checkEmpty()
Throws IllegalStateException if n > 0. |
void |
clear()
Clears the internal state of the Statistic |
double |
evaluate(double[] values,
int begin,
int length)
Returns the geometric mean of the entries in the specified portion of the input array. |
long |
getN()
Returns the number of values that have been added. |
double |
getResult()
Returns the current value of the Statistic. |
StorelessUnivariateStatistic |
getSumLogImpl()
Returns the currently configured sum of logs implementation |
void |
increment(double d)
Updates the internal state of the statistic to reflect the addition of the new value. |
void |
setSumLogImpl(StorelessUnivariateStatistic sumLogImpl)
Sets the implementation for the sum of logs. |
Methods inherited from class org.apache.commons.math.stat.descriptive.AbstractStorelessUnivariateStatistic |
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equals, evaluate, hashCode, incrementAll, incrementAll |
Methods inherited from class org.apache.commons.math.stat.descriptive.AbstractUnivariateStatistic |
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test |
Methods inherited from class java.lang.Object |
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clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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private static final long serialVersionUID
private StorelessUnivariateStatistic sumOfLogs
Constructor Detail |
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public GeometricMean()
public GeometricMean(SumOfLogs sumOfLogs)
Method Detail |
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public void increment(double d)
StorelessUnivariateStatistic
increment
in interface StorelessUnivariateStatistic
increment
in class AbstractStorelessUnivariateStatistic
d
- the new value.StorelessUnivariateStatistic.increment(double)
public double getResult()
StorelessUnivariateStatistic
getResult
in interface StorelessUnivariateStatistic
getResult
in class AbstractStorelessUnivariateStatistic
Double.NaN
if it
has been cleared or just instantiated.StorelessUnivariateStatistic.getResult()
public void clear()
StorelessUnivariateStatistic
clear
in interface StorelessUnivariateStatistic
clear
in class AbstractStorelessUnivariateStatistic
StorelessUnivariateStatistic.clear()
public double evaluate(double[] values, int begin, int length)
See GeometricMean
for details on the computing algorithm.
Throws IllegalArgumentException
if the array is null.
evaluate
in interface UnivariateStatistic
evaluate
in class AbstractStorelessUnivariateStatistic
values
- input array containing the valuesbegin
- first array element to includelength
- the number of elements to include
java.lang.IllegalArgumentException
- if the input array is null or the array
index parameters are not validUnivariateStatistic.evaluate(double[], int, int)
public long getN()
StorelessUnivariateStatistic
StorelessUnivariateStatistic.getN()
public void setSumLogImpl(StorelessUnivariateStatistic sumLogImpl)
Sets the implementation for the sum of logs.
This method must be activated before any data has been added - i.e.,
before increment
has been used to add data;
otherwise an IllegalStateException will be thrown.
sumLogImpl
- the StorelessUnivariateStatistic instance to use
for computing the log sum
java.lang.IllegalStateException
- if data has already been added
(i.e if n > 0)public StorelessUnivariateStatistic getSumLogImpl()
private void checkEmpty()
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