public class FirstMoment extends AbstractStorelessUnivariateStatistic implements Serializable
mean = sum(x_i) / n
where n is the number of observations.
To limit numeric errors, the value of the statistic is computed using the following recursive updating algorithm:
m = the first valuem = m + (new value - m) / (number of observations)
Returns Double.NaN if the dataset is empty.
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.
| Modifier and Type | Field and Description |
|---|---|
protected double |
dev
Deviation of most recently added value from previous first moment.
|
protected double |
m1
First moment of values that have been added
|
protected long |
n
Count of values that have been added
|
protected double |
nDev
Deviation of most recently added value from previous first moment,
normalized by previous sample size.
|
| Constructor and Description |
|---|
FirstMoment()
Create a FirstMoment instance
|
FirstMoment(FirstMoment original)
Copy constructor, creates a new
FirstMoment identical
to the original |
| Modifier and Type | Method and Description |
|---|---|
void |
clear()
Clears the internal state of the Statistic
|
FirstMoment |
copy()
Returns a copy of the statistic with the same internal state.
|
static void |
copy(FirstMoment source,
FirstMoment dest)
Copies source to dest.
|
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.
|
equals, evaluate, evaluate, hashCode, incrementAll, incrementAlltest, testprotected long n
protected double m1
protected double dev
protected double nDev
public FirstMoment()
public FirstMoment(FirstMoment original)
FirstMoment identical
to the originaloriginal - the FirstMoment instance to copypublic void increment(double d)
increment in interface StorelessUnivariateStatisticincrement in class AbstractStorelessUnivariateStatisticd - the new value.public void clear()
clear in interface StorelessUnivariateStatisticclear in class AbstractStorelessUnivariateStatisticpublic double getResult()
getResult in interface StorelessUnivariateStatisticgetResult in class AbstractStorelessUnivariateStatisticDouble.NaN if it
has been cleared or just instantiated.public long getN()
getN in interface StorelessUnivariateStatisticpublic FirstMoment copy()
copy in interface StorelessUnivariateStatisticcopy in interface UnivariateStatisticcopy in class AbstractStorelessUnivariateStatisticpublic static void copy(FirstMoment source, FirstMoment dest)
Neither source nor dest can be null.
source - FirstMoment to copydest - FirstMoment to copy toNullPointerException - if either source or dest is nullCopyright © 1999–2014 The Apache Software Foundation. All rights reserved.