StaTools (Terrier Information Retrieval Platform 4.1 API)

java.lang.Object
- org.terrier.utility.StaTools

```
public class StaTools
extends Object
```
This class implements a series of basic statistical functions.

Constructor Summary

Constructors
Constructor and Description

StaTools()

Constructors
Constructor and Description
`StaTools()`

Method Summary

Methods
Modifier and Type	Method and Description
`static double`	`generalisedMean(double[] data, double p)` Computes the generalized mean, which is a general version of mean and quadratic mean, generalized by parameter p.
`static double`	`geometricMean(double[] data)` Computes the geometric mean.
`static double`	`harmonicMean(double[] data)` Computes the harmonic mean.
`static double`	`max(double[] a)` Return the max of the specified array
`static double`	`max(double[] a, int offset, int length)` Return the max of the specified array
`static float`	`max(float[] a)` Return the max of the specified array
`static int`	`max(int[] a)` Return the max of the specified array
`static double`	`mean(double[] data)` The mean of an array of double values.
`static double`	`mean(double[] data, int start, int length, boolean ascending)` The mean of a sub-array of an array of double values.
`static float`	`mean(float[] data)` find mean of float[]
`static double`	`mean(int[] data)` The mean of an array of integers.
`static double`	`meanNonZero(double[] data)` The mean of an array of doubles, only counting non-zero values.
`static double`	`median(double[] data)` The median of an array of double values.
`static double`	`min(double[] a)` Return the min of the specified array
`static float`	`min(float[] a)` Return the min of the specified array
`static int`	`min(int[] a)` Return the min of the specified array
`static double`	`quadraticMean(double[] data)` Computes the quadratic mean, also known as the root mean square.
`static double`	`standardDeviation(double[] data)` The standard deviation of an array of double values.
`static double[]`	`standardNormalisation(double[] data)` Normalises the data in the specified array to be in range [0,1], with 0 as the minimum, and 1 as the maximum.
`static float[]`	`standardNormalisation(float[] data)` Normalises the data in the specified array to be in range [0,1], with 0 as the minimum, and 1 as the maximum.
`static double`	`stdErrorOfTheMean(double[] data)` This method returns the standard error of the mean for an array of data.
`static double`	`stirlingPower(double n, double m)` This method provides the contract for implementing the Stirling formula for the power series.
`static double`	`sum(double[] data)` The sum of an array of double.
`static int`	`sum(int[] data)` The sum of an array of integers.
`static int`	`sum(int[] data, int length)` The sum of an array of integers.
`static double`	`variance(double[] data)` The variance of an array of double values.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - StaTools
```
public StaTools()
```
- Method Detail
  - stirlingPower
```
public static double stirlingPower(double n,
                   double m)
```
    This method provides the contract for implementing the Stirling formula for the power series.
    
    Parameters:
    n - The parameter of the Stirling formula.
    m - The parameter of the Stirling formula.
    
    Returns:
    the approximation of the power series
  - stdErrorOfTheMean
```
public static double stdErrorOfTheMean(double[] data)
```
    This method returns the standard error of the mean for an array of data.
    
    Parameters:
    data - The sampled data.
    
    Returns:
    The standard error of the mean.
  - max
```
public static final int max(int[] a)
```
    Return the max of the specified array
    
    Parameters:
    a - the array
    
    Returns:
    the maximum value in the arrays
  - max
```
public static final double max(double[] a)
```
    Return the max of the specified array
    
    Parameters:
    a - the array
    
    Returns:
    the maximum value in the arrays
  - max
```
public static final double max(double[] a,
         int offset,
         int length)
```
    Return the max of the specified array
    
    Parameters:
    a - the array
    offset - the offset in the array to start examining from
    length - how many items of the array to consider
    
    Returns:
    the maximum value in the arrays
  - min
```
public static final double min(double[] a)
```
    Return the min of the specified array
    
    Parameters:
    a - the array
    
    Returns:
    the minimum value in the arrays
  - min
```
public static final int min(int[] a)
```
    Return the min of the specified array
    
    Parameters:
    a - the array
    
    Returns:
    the minimum value in the arrays
  - sum
```
public static int sum(int[] data)
```
    The sum of an array of integers.
    
    Parameters:
    data - The integers.
    
    Returns:
    The sum.
  - sum
```
public static int sum(int[] data,
      int length)
```
    The sum of an array of integers.
    
    Parameters:
    data - The integers.
    
    Returns:
    The sum.
  - sum
```
public static double sum(double[] data)
```
    The sum of an array of double.
    
    Parameters:
    data - The integers.
    
    Returns:
    The sum.
  - mean
```
public static double mean(double[] data)
```
    The mean of an array of double values.
    
    Parameters:
    data - The double values.
    
    Returns:
    The mean.
  - mean
```
public static float mean(float[] data)
```
    find mean of float[]
    
    Parameters:
    data -
    
    Returns:
    mean
  - mean
```
public static double mean(double[] data,
          int start,
          int length,
          boolean ascending)
```
    The mean of a sub-array of an array of double values.
    
    Parameters:
    data - The array of double values.
    start - The starting index of the sub-array.
    length - The length of the sub-array.
    ascending - Is the starting index the left (true) or right (false) end of the sub-array?
    
    Returns:
    The mean of the sub-array.
  - mean
```
public static double mean(int[] data)
```
    The mean of an array of integers.
    
    Parameters:
    data - The array of integers.
    
    Returns:
    The mean.
  - meanNonZero
```
public static double meanNonZero(double[] data)
```
    The mean of an array of doubles, only counting non-zero values.
    
    Parameters:
    data - The array of integers.
    
    Returns:
    The mean.
  - median
```
public static double median(double[] data)
```
    The median of an array of double values.
    
    Parameters:
    data - The array of double values.
    
    Returns:
    The median.
  - standardDeviation
```
public static double standardDeviation(double[] data)
```
    The standard deviation of an array of double values.
    
    Parameters:
    data - The array of double values.
    
    Returns:
    The standrad deviation.
  - variance
```
public static double variance(double[] data)
```
    The variance of an array of double values.
    
    Parameters:
    data - The array of double values.
    
    Returns:
    The variance.
  - harmonicMean
```
public static double harmonicMean(double[] data)
```
    Computes the harmonic mean. This assumes that all values are > 0. See http://en.wikipedia.org/wiki/Harmonic_mean.
  - geometricMean
```
public static double geometricMean(double[] data)
```
    Computes the geometric mean. This assumes that all values are > 0. See http://en.wikipedia.org/wiki/Geometric_mean.
  - quadraticMean
```
public static double quadraticMean(double[] data)
```
    Computes the quadratic mean, also known as the root mean square. See http://en.wikipedia.org/wiki/Quadratic_mean.
  - generalisedMean
```
public static double generalisedMean(double[] data,
                     double p)
```
    Computes the generalized mean, which is a general version of mean and quadratic mean, generalized by parameter p. See http://en.wikipedia.org/wiki/Generalized_mean.
  - standardNormalisation
```
public static double[] standardNormalisation(double[] data)
```
    Normalises the data in the specified array to be in range [0,1], with 0 as the minimum, and 1 as the maximum. RETURNS THE SAME ARRAY OBJECT - i.e. changes are made in place.
    
    Parameters:
    data -
  - standardNormalisation
```
public static float[] standardNormalisation(float[] data)
```
    Normalises the data in the specified array to be in range [0,1], with 0 as the minimum, and 1 as the maximum. RETURNS THE SAME ARRAY OBJECT - i.e. changes are made in place.
    
    Parameters:
    data -
  - min
```
public static final float min(float[] a)
```
    Return the min of the specified array
    
    Parameters:
    a - the array
    
    Returns:
    the minimum value in the arrays
  - max
```
public static final float max(float[] a)
```
    Return the max of the specified array
    
    Parameters:
    a - the array
    
    Returns:
    the maximum value in the arrays

Class StaTools

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

StaTools

Method Detail

stirlingPower

stdErrorOfTheMean

max

max

max

min

min

sum

sum

sum

mean

mean

mean

mean

meanNonZero

median

standardDeviation

variance

harmonicMean

geometricMean

quadraticMean

generalisedMean

standardNormalisation

standardNormalisation

min

max