org.apache.commons.math3.stat.descriptive

## Class SynchronizedDescriptiveStatistics

- java.lang.Object
- - org.apache.commons.math3.stat.descriptive.DescriptiveStatistics
  - - org.apache.commons.math3.stat.descriptive.SynchronizedDescriptiveStatistics

All Implemented Interfaces:
  java.io.Serializable, StatisticalSummary

    public class SynchronizedDescriptiveStatistics
    extends DescriptiveStatistics

Implementation of `DescriptiveStatistics` that is safe to use in a multithreaded environment. Multiple threads can safely operate on a single instance without causing runtime exceptions due to race conditions. In effect, this implementation makes modification and access methods atomic operations for a single instance. That is to say, as one thread is computing a statistic from the instance, no other thread can modify the instance nor compute another statistic.

Since:
  1.2
Version:
  $Id: SynchronizedDescriptiveStatistics.java 1416643 2012-12-03 19:37:14Z tn $
See Also:
  Serialized Form

### Field Summary

Fields
`private static long` `serialVersionUID` Serialization UID

### Fields inherited from class org.apache.commons.math3.stat.descriptive.DescriptiveStatistics

`INFINITE_WINDOW, windowSize`

### Constructor Summary

Constructors
Constructor and Description
`SynchronizedDescriptiveStatistics()` Construct an instance with infinite window
`SynchronizedDescriptiveStatistics(int window)` Construct an instance with finite window
`SynchronizedDescriptiveStatistics(SynchronizedDescriptiveStatistics original)` A copy constructor.

### Method Summary

Methods
`void` `addValue(double v)` Adds the value to the dataset.
`double` `apply(UnivariateStatistic stat)` Apply the given statistic to the data associated with this set of statistics.
`void` `clear()` Resets all statistics and storage
`SynchronizedDescriptiveStatistics` `copy()` Returns a copy of this SynchronizedDescriptiveStatistics instance with the same internal state.
`static void` `copy(SynchronizedDescriptiveStatistics source, SynchronizedDescriptiveStatistics dest)` Copies source to dest.
`double` `getElement(int index)` Returns the element at the specified index
`long` `getN()` Returns the number of available values
`double` `getStandardDeviation()` Returns the standard deviation of the available values.
`double[]` `getValues()` Returns the current set of values in an array of double primitives.
`int` `getWindowSize()` Returns the maximum number of values that can be stored in the dataset, or INFINITE_WINDOW (-1) if there is no limit.
`void` `setWindowSize(int windowSize)` WindowSize controls the number of values that contribute to the reported statistics.
`java.lang.String` `toString()` Generates a text report displaying univariate statistics from values that have been added.

### Methods inherited from class org.apache.commons.math3.stat.descriptive.DescriptiveStatistics

`copy, getGeometricMean, getGeometricMeanImpl, getKurtosis, getKurtosisImpl, getMax, getMaxImpl, getMean, getMeanImpl, getMin, getMinImpl, getPercentile, getPercentileImpl, getPopulationVariance, getSkewness, getSkewnessImpl, getSortedValues, getSum, getSumImpl, getSumsq, getSumsqImpl, getVariance, getVarianceImpl, removeMostRecentValue, replaceMostRecentValue, setGeometricMeanImpl, setKurtosisImpl, setMaxImpl, setMeanImpl, setMinImpl, setPercentileImpl, setSkewnessImpl, setSumImpl, setSumsqImpl, setVarianceImpl`

### Methods inherited from class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

### Field Detail

#### serialVersionUID

    private static final long serialVersionUID

Serialization UID

See Also:
  Constant Field Values

### Constructor Detail

#### SynchronizedDescriptiveStatistics

    public SynchronizedDescriptiveStatistics()

Construct an instance with infinite window

#### SynchronizedDescriptiveStatistics

    public SynchronizedDescriptiveStatistics(int window)
                                      throws MathIllegalArgumentException

Construct an instance with finite window

Parameters:
  `window` - the finite window size.
Throws:
  `MathIllegalArgumentException` - if window size is less than 1 but not equal to `DescriptiveStatistics.INFINITE_WINDOW`

#### SynchronizedDescriptiveStatistics

    public SynchronizedDescriptiveStatistics(SynchronizedDescriptiveStatistics original)
                                      throws NullArgumentException

A copy constructor. Creates a deep-copy of the `original`.

Parameters:
  `original` - the `SynchronizedDescriptiveStatistics` instance to copy
Throws:
  `NullArgumentException` - if original is null

### Method Detail

#### addValue

    public void addValue(double v)

Adds the value to the dataset. If the dataset is at the maximum size (i.e., the number of stored elements equals the currently configured windowSize), the first (oldest) element in the dataset is discarded to make room for the new value.

Overrides:
  `addValue` in class `DescriptiveStatistics`
Parameters:
  `v` - the value to be added

#### apply

    public double apply(UnivariateStatistic stat)

Apply the given statistic to the data associated with this set of statistics.

Overrides:
  `apply` in class `DescriptiveStatistics`
Parameters:
  `stat` - the statistic to apply
Returns:
  the computed value of the statistic.

#### clear

    public void clear()

Resets all statistics and storage

Overrides:
  `clear` in class `DescriptiveStatistics`

#### getElement

    public double getElement(int index)

Returns the element at the specified index

Overrides:
  `getElement` in class `DescriptiveStatistics`
Parameters:
  `index` - The Index of the element
Returns:
  return the element at the specified index

#### getN

    public long getN()

Returns the number of available values

Specified by:
  `getN` in interface `StatisticalSummary`
Overrides:
  `getN` in class `DescriptiveStatistics`
Returns:
  The number of available values

#### getStandardDeviation

    public double getStandardDeviation()

Returns the standard deviation of the available values.

Specified by:
  `getStandardDeviation` in interface `StatisticalSummary`
Overrides:
  `getStandardDeviation` in class `DescriptiveStatistics`
Returns:
  The standard deviation, Double.NaN if no values have been added or 0.0 for a single value set.

#### getValues

    public double[] getValues()

Returns the current set of values in an array of double primitives. The order of addition is preserved. The returned array is a fresh copy of the underlying data -- i.e., it is not a reference to the stored data.

Overrides:
  `getValues` in class `DescriptiveStatistics`
Returns:
  returns the current set of numbers in the order in which they were added to this set

#### getWindowSize

    public int getWindowSize()

Returns the maximum number of values that can be stored in the dataset, or INFINITE_WINDOW (-1) if there is no limit.

Overrides:
  `getWindowSize` in class `DescriptiveStatistics`
Returns:
  The current window size or -1 if its Infinite.

#### setWindowSize

    public void setWindowSize(int windowSize)
                       throws MathIllegalArgumentException

WindowSize controls the number of values that contribute to the reported statistics. For example, if windowSize is set to 3 and the values {1,2,3,4,5} have been added in that order then the available values are {3,4,5} and all reported statistics will be based on these values. If `windowSize` is decreased as a result of this call and there are more than the new value of elements in the current dataset, values from the front of the array are discarded to reduce the dataset to `windowSize` elements.

Overrides:
  `setWindowSize` in class `DescriptiveStatistics`
Parameters:
  `windowSize` - sets the size of the window.
Throws:
  `MathIllegalArgumentException` - if window size is less than 1 but not equal to `DescriptiveStatistics.INFINITE_WINDOW`

#### toString

    public java.lang.String toString()

Generates a text report displaying univariate statistics from values that have been added. Each statistic is displayed on a separate line.

Overrides:
  `toString` in class `DescriptiveStatistics`
Returns:
  String with line feeds displaying statistics

#### copy

    public SynchronizedDescriptiveStatistics copy()

Returns a copy of this SynchronizedDescriptiveStatistics instance with the same internal state.

Overrides:
  `copy` in class `DescriptiveStatistics`
Returns:
  a copy of this

#### copy

    public static void copy(SynchronizedDescriptiveStatistics source,
            SynchronizedDescriptiveStatistics dest)
                     throws NullArgumentException

Copies source to dest.

Neither source nor dest can be null.

Acquires synchronization lock on source, then dest before copying.

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