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## org.apache.commons.math.stat.descriptive
Class SummaryStatistics

    java.lang.Object
      org.apache.commons.math.stat.descriptive.SummaryStatistics

All Implemented Interfaces:
  java.io.Serializable, StatisticalSummary

Direct Known Subclasses:
  AggregateSummaryStatistics.AggregatingSummaryStatistics, SynchronizedSummaryStatistics

    public class SummaryStatistics

extends java.lang.Object
implements StatisticalSummary, java.io.Serializable

Computes summary statistics for a stream of data values added using the `addValue` method. The data values are not stored in memory, so this class can be used to compute statistics for very large data streams.

The `StorelessUnivariateStatistic` instances used to maintain summary state and compute statistics are configurable via setters. For example, the default implementation for the variance can be overridden by calling `setVarianceImpl(StorelessUnivariateStatistic)`. Actual parameters to these methods must implement the `StorelessUnivariateStatistic` interface and configuration must be completed before `addValue` is called. No configuration is necessary to use the default, commons-math provided implementations.

Note: This class is not thread-safe. Use `SynchronizedSummaryStatistics` if concurrent access from multiple threads is required.

Version:
  $Revision: 811833 $ $Date: 2009-09-06 12:27:50 -0400 (Sun, 06 Sep 2009) $
See Also:
  Serialized Form

Field Summary
`protected GeometricMean` | `geoMean` geoMean of values that have been added
`private StorelessUnivariateStatistic` | `geoMeanImpl` Geometric mean statistic implementation - can be reset by setter.
`protected Max` | `max` max of values that have been added
`private StorelessUnivariateStatistic` | `maxImpl` Maximum statistic implementation - can be reset by setter.
`protected Mean` | `mean` mean of values that have been added
`private StorelessUnivariateStatistic` | `meanImpl` Mean statistic implementation - can be reset by setter.
`protected Min` | `min` min of values that have been added
`private StorelessUnivariateStatistic` | `minImpl` Minimum statistic implementation - can be reset by setter.
`protected long` | `n` count of values that have been added
`protected SecondMoment` | `secondMoment` SecondMoment is used to compute the mean and variance
`private static long` | `serialVersionUID` Serialization UID
`protected Sum` | `sum` sum of values that have been added
`private StorelessUnivariateStatistic` | `sumImpl` Sum statistic implementation - can be reset by setter.
`protected SumOfLogs` | `sumLog` sumLog of values that have been added
`private StorelessUnivariateStatistic` | `sumLogImpl` Sum of log statistic implementation - can be reset by setter.
`protected SumOfSquares` | `sumsq` sum of the square of each value that has been added
`private StorelessUnivariateStatistic` | `sumsqImpl` Sum of squares statistic implementation - can be reset by setter.
`protected Variance` | `variance` variance of values that have been added
`private StorelessUnivariateStatistic` | `varianceImpl` Variance statistic implementation - can be reset by setter.

Constructor Summary
`SummaryStatistics()` Construct a SummaryStatistics instance
`SummaryStatistics(SummaryStatistics original)` A copy constructor.

Method Summary
`void` | `addValue(double value)` Add a value to the data
`private void` | `checkEmpty()` Throws IllegalStateException if n > 0.
`void` | `clear()` Resets all statistics and storage
`SummaryStatistics` | `copy()` Returns a copy of this SummaryStatistics instance with the same internal state.
`static void` | `copy(SummaryStatistics source, SummaryStatistics dest)` Copies source to dest.
`boolean` | `equals(java.lang.Object object)` Returns true iff `object` is a `SummaryStatistics` instance and all statistics have the same values as this.
`StorelessUnivariateStatistic` | `getGeoMeanImpl()` Returns the currently configured geometric mean implementation
`double` | `getGeometricMean()` Returns the geometric mean of the values that have been added.
`double` | `getMax()` Returns the maximum of the values that have been added.
`StorelessUnivariateStatistic` | `getMaxImpl()` Returns the currently configured maximum implementation
`double` | `getMean()` Returns the mean of the values that have been added.
`StorelessUnivariateStatistic` | `getMeanImpl()` Returns the currently configured mean implementation
`double` | `getMin()` Returns the minimum of the values that have been added.
`StorelessUnivariateStatistic` | `getMinImpl()` Returns the currently configured minimum implementation
`long` | `getN()` Returns the number of available values
`double` | `getSecondMoment()` Returns a statistic related to the Second Central Moment.
`double` | `getStandardDeviation()` Returns the standard deviation of the values that have been added.
`double` | `getSum()` Returns the sum of the values that have been added
`StorelessUnivariateStatistic` | `getSumImpl()` Returns the currently configured Sum implementation
`StorelessUnivariateStatistic` | `getSumLogImpl()` Returns the currently configured sum of logs implementation
`StatisticalSummary` | `getSummary()` Return a `StatisticalSummaryValues` instance reporting current statistics.
`double` | `getSumOfLogs()` Returns the sum of the logs of the values that have been added.
`double` | `getSumsq()` Returns the sum of the squares of the values that have been added.
`StorelessUnivariateStatistic` | `getSumsqImpl()` Returns the currently configured sum of squares implementation
`double` | `getVariance()` Returns the variance of the values that have been added.
`StorelessUnivariateStatistic` | `getVarianceImpl()` Returns the currently configured variance implementation
`int` | `hashCode()` Returns hash code based on values of statistics
`void` | `setGeoMeanImpl(StorelessUnivariateStatistic geoMeanImpl)` Sets the implementation for the geometric mean.
`void` | `setMaxImpl(StorelessUnivariateStatistic maxImpl)` Sets the implementation for the maximum.
`void` | `setMeanImpl(StorelessUnivariateStatistic meanImpl)` Sets the implementation for the mean.
`void` | `setMinImpl(StorelessUnivariateStatistic minImpl)` Sets the implementation for the minimum.
`void` | `setSumImpl(StorelessUnivariateStatistic sumImpl)` Sets the implementation for the Sum.
`void` | `setSumLogImpl(StorelessUnivariateStatistic sumLogImpl)` Sets the implementation for the sum of logs.
`void` | `setSumsqImpl(StorelessUnivariateStatistic sumsqImpl)` Sets the implementation for the sum of squares.
`void` | `setVarianceImpl(StorelessUnivariateStatistic varianceImpl)` Sets the implementation for the variance.
`java.lang.String` | `toString()` Generates a text report displaying summary statistics from values that have been added.

Methods inherited from class java.lang.Object
`clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

Field Detail

### serialVersionUID

    private static final long serialVersionUID

  Serialization UID

  See Also:
    Constant Field Values

### n

    protected long n

  count of values that have been added

### secondMoment

    protected SecondMoment secondMoment

  SecondMoment is used to compute the mean and variance

### sum

    protected Sum sum

  sum of values that have been added

### sumsq

    protected SumOfSquares sumsq

  sum of the square of each value that has been added

### min

    protected Min min

  min of values that have been added

### max

    protected Max max

  max of values that have been added

### sumLog

    protected SumOfLogs sumLog

  sumLog of values that have been added

### geoMean

    protected GeometricMean geoMean

  geoMean of values that have been added

### mean

    protected Mean mean

  mean of values that have been added

### variance

    protected Variance variance

  variance of values that have been added

### sumImpl

    private StorelessUnivariateStatistic sumImpl

  Sum statistic implementation - can be reset by setter.

### sumsqImpl

    private StorelessUnivariateStatistic sumsqImpl

  Sum of squares statistic implementation - can be reset by setter.

### minImpl

    private StorelessUnivariateStatistic minImpl

  Minimum statistic implementation - can be reset by setter.

### maxImpl

    private StorelessUnivariateStatistic maxImpl

  Maximum statistic implementation - can be reset by setter.

### sumLogImpl

    private StorelessUnivariateStatistic sumLogImpl

  Sum of log statistic implementation - can be reset by setter.

### geoMeanImpl

    private StorelessUnivariateStatistic geoMeanImpl

  Geometric mean statistic implementation - can be reset by setter.

### meanImpl

    private StorelessUnivariateStatistic meanImpl

  Mean statistic implementation - can be reset by setter.

### varianceImpl

    private StorelessUnivariateStatistic varianceImpl

  Variance statistic implementation - can be reset by setter.

Constructor Detail

### SummaryStatistics

    public SummaryStatistics()

  Construct a SummaryStatistics instance

### SummaryStatistics

    public SummaryStatistics(SummaryStatistics original)

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

  Parameters:
    `original` - the `SummaryStatistics` instance to copy

Method Detail

### getSummary

    public StatisticalSummary getSummary()

  Return a `StatisticalSummaryValues` instance reporting current statistics.

  Returns:
    Current values of statistics

### addValue

    public void addValue(double value)

  Add a value to the data

  Parameters:
    `value` - the value to add

### getN

    public long getN()

  Returns the number of available values

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

### getSum

    public double getSum()

  Returns the sum of the values that have been added

  Specified by:
    `getSum` in interface `StatisticalSummary`
  Returns:
    The sum or `Double.NaN` if no values have been added

### getSumsq

    public double getSumsq()

  Returns the sum of the squares of the values that have been added.

  Double.NaN is returned if no values have been added.

  Returns:
    The sum of squares

### getMean

    public double getMean()

  Returns the mean of the values that have been added.

  Double.NaN is returned if no values have been added.

  Specified by:
    `getMean` in interface `StatisticalSummary`
  Returns:
    the mean

### getStandardDeviation

    public double getStandardDeviation()

  Returns the standard deviation of the values that have been added.

  Double.NaN is returned if no values have been added.

  Specified by:
    `getStandardDeviation` in interface `StatisticalSummary`
  Returns:
    the standard deviation

### getVariance

    public double getVariance()

  Returns the variance of the values that have been added.

  Double.NaN is returned if no values have been added.

  Specified by:
    `getVariance` in interface `StatisticalSummary`
  Returns:
    the variance

### getMax

    public double getMax()

  Returns the maximum of the values that have been added.

  Double.NaN is returned if no values have been added.

  Specified by:
    `getMax` in interface `StatisticalSummary`
  Returns:
    the maximum

### getMin

    public double getMin()

  Returns the minimum of the values that have been added.

  Double.NaN is returned if no values have been added.

  Specified by:
    `getMin` in interface `StatisticalSummary`
  Returns:
    the minimum

### getGeometricMean

    public double getGeometricMean()

  Returns the geometric mean of the values that have been added.

  Double.NaN is returned if no values have been added.

  Returns:
    the geometric mean

### getSumOfLogs

    public double getSumOfLogs()

  Returns the sum of the logs of the values that have been added.

  Double.NaN is returned if no values have been added.

  Returns:
    the sum of logs
  Since:
    1.2

### getSecondMoment

    public double getSecondMoment()

  Returns a statistic related to the Second Central Moment. Specifically, what is returned is the sum of squared deviations from the sample mean among the values that have been added.

  Returns `Double.NaN` if no data values have been added and returns `0` if there is just one value in the data set.

  Returns:
    second central moment statistic
  Since:
    2.0

### toString

    public java.lang.String toString()

  Generates a text report displaying summary statistics from values that have been added.

  Overrides:
    `toString` in class `java.lang.Object`
  Returns:
    String with line feeds displaying statistics
  Since:
    1.2

### clear

    public void clear()

  Resets all statistics and storage

### equals

    public boolean equals(java.lang.Object object)

  Returns true iff `object` is a `SummaryStatistics` instance and all statistics have the same values as this.

  Overrides:
    `equals` in class `java.lang.Object`
  Parameters:
    `object` - the object to test equality against.
  Returns:
    true if object equals this

### hashCode

    public int hashCode()

  Returns hash code based on values of statistics

  Overrides:
    `hashCode` in class `java.lang.Object`
  Returns:
    hash code

### getSumImpl

    public StorelessUnivariateStatistic getSumImpl()

  Returns the currently configured Sum implementation

  Returns:
    the StorelessUnivariateStatistic implementing the sum
  Since:
    1.2

### setSumImpl

    public void setSumImpl(StorelessUnivariateStatistic sumImpl)

  Sets the implementation for the Sum.

  This method must be activated before any data has been added - i.e., before `addValue` has been used to add data; otherwise an IllegalStateException will be thrown.

  Parameters:
    `sumImpl` - the StorelessUnivariateStatistic instance to use for computing the Sum
  Throws:
    `java.lang.IllegalStateException` - if data has already been added (i.e if n > 0)
  Since:
    1.2

### getSumsqImpl

    public StorelessUnivariateStatistic getSumsqImpl()

  Returns the currently configured sum of squares implementation

  Returns:
    the StorelessUnivariateStatistic implementing the sum of squares
  Since:
    1.2

### setSumsqImpl

    public void setSumsqImpl(StorelessUnivariateStatistic sumsqImpl)

  Sets the implementation for the sum of squares.

  This method must be activated before any data has been added - i.e., before `addValue` has been used to add data; otherwise an IllegalStateException will be thrown.

  Parameters:
    `sumsqImpl` - the StorelessUnivariateStatistic instance to use for computing the sum of squares
  Throws:
    `java.lang.IllegalStateException` - if data has already been added (i.e if n > 0)
  Since:
    1.2

### getMinImpl

    public StorelessUnivariateStatistic getMinImpl()

  Returns the currently configured minimum implementation

  Returns:
    the StorelessUnivariateStatistic implementing the minimum
  Since:
    1.2

### setMinImpl

    public void setMinImpl(StorelessUnivariateStatistic minImpl)

  Sets the implementation for the minimum.

  This method must be activated before any data has been added - i.e., before `addValue` has been used to add data; otherwise an IllegalStateException will be thrown.

  Parameters:
    `minImpl` - the StorelessUnivariateStatistic instance to use for computing the minimum
  Throws:
    `java.lang.IllegalStateException` - if data has already been added (i.e if n > 0)
  Since:
    1.2

### getMaxImpl

    public StorelessUnivariateStatistic getMaxImpl()

  Returns the currently configured maximum implementation

  Returns:
    the StorelessUnivariateStatistic implementing the maximum
  Since:
    1.2

### setMaxImpl

    public void setMaxImpl(StorelessUnivariateStatistic maxImpl)

  Sets the implementation for the maximum.

  This method must be activated before any data has been added - i.e., before `addValue` has been used to add data; otherwise an IllegalStateException will be thrown.

  Parameters:
    `maxImpl` - the StorelessUnivariateStatistic instance to use for computing the maximum
  Throws:
    `java.lang.IllegalStateException` - if data has already been added (i.e if n > 0)
  Since:
    1.2

### getSumLogImpl

    public StorelessUnivariateStatistic getSumLogImpl()

  Returns the currently configured sum of logs implementation

  Returns:
    the StorelessUnivariateStatistic implementing the log sum
  Since:
    1.2

### setSumLogImpl

    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 `addValue` has been used to add data; otherwise an IllegalStateException will be thrown.

  Parameters:
    `sumLogImpl` - the StorelessUnivariateStatistic instance to use for computing the log sum
  Throws:
    `java.lang.IllegalStateException` - if data has already been added (i.e if n > 0)
  Since:
    1.2

### getGeoMeanImpl

    public StorelessUnivariateStatistic getGeoMeanImpl()

  Returns the currently configured geometric mean implementation

  Returns:
    the StorelessUnivariateStatistic implementing the geometric mean
  Since:
    1.2

### setGeoMeanImpl

    public void setGeoMeanImpl(StorelessUnivariateStatistic geoMeanImpl)

  Sets the implementation for the geometric mean.

  This method must be activated before any data has been added - i.e., before `addValue` has been used to add data; otherwise an IllegalStateException will be thrown.

  Parameters:
    `geoMeanImpl` - the StorelessUnivariateStatistic instance to use for computing the geometric mean
  Throws:
    `java.lang.IllegalStateException` - if data has already been added (i.e if n > 0)
  Since:
    1.2

### getMeanImpl

    public StorelessUnivariateStatistic getMeanImpl()

  Returns the currently configured mean implementation

  Returns:
    the StorelessUnivariateStatistic implementing the mean
  Since:
    1.2

### setMeanImpl

    public void setMeanImpl(StorelessUnivariateStatistic meanImpl)

  Sets the implementation for the mean.

  This method must be activated before any data has been added - i.e., before `addValue` has been used to add data; otherwise an IllegalStateException will be thrown.

  Parameters:
    `meanImpl` - the StorelessUnivariateStatistic instance to use for computing the mean
  Throws:
    `java.lang.IllegalStateException` - if data has already been added (i.e if n > 0)
  Since:
    1.2

### getVarianceImpl

    public StorelessUnivariateStatistic getVarianceImpl()

  Returns the currently configured variance implementation

  Returns:
    the StorelessUnivariateStatistic implementing the variance
  Since:
    1.2

### setVarianceImpl

    public void setVarianceImpl(StorelessUnivariateStatistic varianceImpl)

  Sets the implementation for the variance.

  This method must be activated before any data has been added - i.e., before `addValue` has been used to add data; otherwise an IllegalStateException will be thrown.

  Parameters:
    `varianceImpl` - the StorelessUnivariateStatistic instance to use for computing the variance
  Throws:
    `java.lang.IllegalStateException` - if data has already been added (i.e if n > 0)
  Since:
    1.2

### checkEmpty

    private void checkEmpty()

  Throws IllegalStateException if n > 0.

### copy

    public SummaryStatistics copy()

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

  Returns:
    a copy of this

### copy

    public static void copy(SummaryStatistics source,
                            SummaryStatistics dest)

  Copies source to dest.

  Neither source nor dest can be null.

  Parameters:
    `source` - SummaryStatistics to copy
    `dest` - SummaryStatistics to copy to
  Throws:
    `java.lang.NullPointerException` - if either source or dest is null

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