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:
    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
  See Also:
    Serialized Form

- - ### Field Summary

    - ### 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
    Modifier and Type | Method and Description
    --- | ---
    `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` | `getQuadraticMean()` Returns the quadratic mean, a.k.a.
    `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.
    `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`

- - ### 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.

    - #### getQuadraticMean

          public double getQuadraticMean()

      Returns the quadratic mean, a.k.a. root-mean-square of the available values
      Overrides:
        `getQuadraticMean` in class `DescriptiveStatistics`
      Returns:
        The quadratic mean or `Double.NaN` if no values have been added.

    - #### 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 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

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