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java.lang.Objectorg.apache.commons.math.stat.StatUtils
public final class StatUtils
StatUtils provides static methods for computing statistics based on data stored in double[] arrays.
| Method Summary | |
|---|---|
static double |
geometricMean(double[] values)
Returns the geometric mean of the entries in the input array, or Double.NaN if the array is empty. |
static double |
geometricMean(double[] values,
int begin,
int length)
Returns the geometric mean of the entries in the specified portion of the input array, or Double.NaN if the designated subarray
is empty. |
static double |
max(double[] values)
Returns the maximum of the entries in the input array, or Double.NaN if the array is empty. |
static double |
max(double[] values,
int begin,
int length)
Returns the maximum of the entries in the specified portion of the input array, or Double.NaN if the designated subarray
is empty. |
static double |
mean(double[] values)
Returns the arithmetic mean of the entries in the input array, or Double.NaN if the array is empty. |
static double |
mean(double[] values,
int begin,
int length)
Returns the arithmetic mean of the entries in the specified portion of the input array, or Double.NaN if the designated subarray
is empty. |
static double |
meanDifference(double[] sample1,
double[] sample2)
Returns the mean of the (signed) differences between corresponding elements of the input arrays -- i.e., sum(sample1[i] - sample2[i]) / sample1.length. |
static double |
min(double[] values)
Returns the minimum of the entries in the input array, or Double.NaN if the array is empty. |
static double |
min(double[] values,
int begin,
int length)
Returns the minimum of the entries in the specified portion of the input array, or Double.NaN if the designated subarray
is empty. |
static double |
percentile(double[] values,
double p)
Returns an estimate of the pth percentile of the values
in the values array. |
static double |
percentile(double[] values,
int begin,
int length,
double p)
Returns an estimate of the pth percentile of the values
in the values array, starting with the element in (0-based)
position begin in the array and including length
values. |
static double |
product(double[] values)
Returns the product of the entries in the input array, or Double.NaN if the array is empty. |
static double |
product(double[] values,
int begin,
int length)
Returns the product of the entries in the specified portion of the input array, or Double.NaN if the designated subarray
is empty. |
static double |
sum(double[] values)
Returns the sum of the values in the input array, or Double.NaN if the array is empty. |
static double |
sum(double[] values,
int begin,
int length)
Returns the sum of the entries in the specified portion of the input array, or Double.NaN if the designated subarray
is empty. |
static double |
sumDifference(double[] sample1,
double[] sample2)
Returns the sum of the (signed) differences between corresponding elements of the input arrays -- i.e., sum(sample1[i] - sample2[i]). |
static double |
sumLog(double[] values)
Returns the sum of the natural logs of the entries in the input array, or Double.NaN if the array is empty. |
static double |
sumLog(double[] values,
int begin,
int length)
Returns the sum of the natural logs of the entries in the specified portion of the input array, or Double.NaN if the designated subarray
is empty. |
static double |
sumSq(double[] values)
Returns the sum of the squares of the entries in the input array, or Double.NaN if the array is empty. |
static double |
sumSq(double[] values,
int begin,
int length)
Returns the sum of the squares of the entries in the specified portion of the input array, or Double.NaN if the designated subarray
is empty. |
static double |
variance(double[] values)
Returns the variance of the entries in the input array, or Double.NaN if the array is empty. |
static double |
variance(double[] values,
double mean)
Returns the variance of the entries in the input array, using the precomputed mean value. |
static double |
variance(double[] values,
double mean,
int begin,
int length)
Returns the variance of the entries in the specified portion of the input array, using the precomputed mean value. |
static double |
variance(double[] values,
int begin,
int length)
Returns the variance of the entries in the specified portion of the input array, or Double.NaN if the designated subarray
is empty. |
static double |
varianceDifference(double[] sample1,
double[] sample2,
double meanDifference)
Returns the variance of the (signed) differences between corresponding elements of the input arrays -- i.e., var(sample1[i] - sample2[i]). |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Method Detail |
|---|
public static double sum(double[] values)
Double.NaN if the array is empty.
Throws IllegalArgumentException if the input array
is null.
values - array of values to sum
Double.NaN if the array
is empty
IllegalArgumentException - if the array is null
public static double sum(double[] values,
int begin,
int length)
Double.NaN if the designated subarray
is empty.
Throws IllegalArgumentException if the array is null.
values - the input arraybegin - index of the first array element to includelength - the number of elements to include
IllegalArgumentException - if the array is null or the array index
parameters are not validpublic static double sumSq(double[] values)
Double.NaN if the array is empty.
Throws IllegalArgumentException if the array is null.
values - input array
Double.NaN if the
array is empty
IllegalArgumentException - if the array is null
public static double sumSq(double[] values,
int begin,
int length)
Double.NaN if the designated subarray
is empty.
Throws IllegalArgumentException if the array is null.
values - the input arraybegin - index of the first array element to includelength - the number of elements to include
IllegalArgumentException - if the array is null or the array index
parameters are not validpublic static double product(double[] values)
Double.NaN if the array is empty.
Throws IllegalArgumentException if the array is null.
values - the input array
IllegalArgumentException - if the array is null
public static double product(double[] values,
int begin,
int length)
Double.NaN if the designated subarray
is empty.
Throws IllegalArgumentException if the array is null.
values - the input arraybegin - index of the first array element to includelength - the number of elements to include
IllegalArgumentException - if the array is null or the array index
parameters are not validpublic static double sumLog(double[] values)
Double.NaN if the array is empty.
Throws IllegalArgumentException if the array is null.
See SumOfLogs.
values - the input array
IllegalArgumentException - if the array is null
public static double sumLog(double[] values,
int begin,
int length)
Double.NaN if the designated subarray
is empty.
Throws IllegalArgumentException if the array is null.
See SumOfLogs.
values - the input arraybegin - index of the first array element to includelength - the number of elements to include
IllegalArgumentException - if the array is null or the array index
parameters are not validpublic static double mean(double[] values)
Double.NaN if the array is empty.
Throws IllegalArgumentException if the array is null.
See Mean for
details on the computing algorithm.
values - the input array
IllegalArgumentException - if the array is null
public static double mean(double[] values,
int begin,
int length)
Double.NaN if the designated subarray
is empty.
Throws IllegalArgumentException if the array is null.
See Mean for
details on the computing algorithm.
values - the input arraybegin - index of the first array element to includelength - the number of elements to include
IllegalArgumentException - if the array is null or the array index
parameters are not validpublic static double geometricMean(double[] values)
Double.NaN if the array is empty.
Throws IllegalArgumentException if the array is null.
See GeometricMean
for details on the computing algorithm.
values - the input array
IllegalArgumentException - if the array is null
public static double geometricMean(double[] values,
int begin,
int length)
Double.NaN if the designated subarray
is empty.
Throws IllegalArgumentException if the array is null.
See GeometricMean
for details on the computing algorithm.
values - the input arraybegin - index of the first array element to includelength - the number of elements to include
IllegalArgumentException - if the array is null or the array index
parameters are not validpublic static double variance(double[] values)
Double.NaN if the array is empty.
See Variance for
details on the computing algorithm.
Returns 0 for a single-value (i.e. length = 1) sample.
Throws IllegalArgumentException if the array is null.
values - the input array
IllegalArgumentException - if the array is null
public static double variance(double[] values,
int begin,
int length)
Double.NaN if the designated subarray
is empty.
See Variance for
details on the computing algorithm.
Returns 0 for a single-value (i.e. length = 1) sample.
Throws IllegalArgumentException if the array is null or the
array index parameters are not valid.
values - the input arraybegin - index of the first array element to includelength - the number of elements to include
IllegalArgumentException - if the array is null or the array index
parameters are not valid
public static double variance(double[] values,
double mean,
int begin,
int length)
Double.NaN if the designated subarray is empty.
See Variance for
details on the computing algorithm.
The formula used assumes that the supplied mean value is the arithmetic mean of the sample data, not a known population parameter. This method is supplied only to save computation when the mean has already been computed.
Returns 0 for a single-value (i.e. length = 1) sample.
Throws IllegalArgumentException if the array is null or the
array index parameters are not valid.
values - the input arraymean - the precomputed mean valuebegin - index of the first array element to includelength - the number of elements to include
IllegalArgumentException - if the array is null or the array index
parameters are not valid
public static double variance(double[] values,
double mean)
Double.NaN if the array
is empty.
See Variance for
details on the computing algorithm.
The formula used assumes that the supplied mean value is the arithmetic mean of the sample data, not a known population parameter. This method is supplied only to save computation when the mean has already been computed.
Returns 0 for a single-value (i.e. length = 1) sample.
Throws IllegalArgumentException if the array is null.
values - the input arraymean - the precomputed mean value
IllegalArgumentException - if the array is nullpublic static double max(double[] values)
Double.NaN if the array is empty.
Throws IllegalArgumentException if the array is null.
NaN iff all values are NaN
(i.e. NaN values have no impact on the value of the statistic).Double.POSITIVE_INFINITY,
the result is Double.POSITIVE_INFINITY.
values - the input array
IllegalArgumentException - if the array is null
public static double max(double[] values,
int begin,
int length)
Double.NaN if the designated subarray
is empty.
Throws IllegalArgumentException if the array is null or
the array index parameters are not valid.
NaN iff all values are NaN
(i.e. NaN values have no impact on the value of the statistic).Double.POSITIVE_INFINITY,
the result is Double.POSITIVE_INFINITY.
values - the input arraybegin - index of the first array element to includelength - the number of elements to include
IllegalArgumentException - if the array is null or the array index
parameters are not validpublic static double min(double[] values)
Double.NaN if the array is empty.
Throws IllegalArgumentException if the array is null.
NaN iff all values are NaN
(i.e. NaN values have no impact on the value of the statistic).Double.NEGATIVE_INFINITY,
the result is Double.NEGATIVE_INFINITY.
values - the input array
IllegalArgumentException - if the array is null
public static double min(double[] values,
int begin,
int length)
Double.NaN if the designated subarray
is empty.
Throws IllegalArgumentException if the array is null or
the array index parameters are not valid.
NaN iff all values are NaN
(i.e. NaN values have no impact on the value of the statistic).Double.NEGATIVE_INFINITY,
the result is Double.NEGATIVE_INFINITY.
values - the input arraybegin - index of the first array element to includelength - the number of elements to include
IllegalArgumentException - if the array is null or the array index
parameters are not valid
public static double percentile(double[] values,
double p)
pth percentile of the values
in the values array.
Double.NaN if values has length
0p) values[0]
if values has length 1IllegalArgumentException if values
is null or p is not a valid quantile value (p must be greater than 0
and less than or equal to 100)
See Percentile for
a description of the percentile estimation algorithm used.
values - input array of valuesp - the percentile value to compute
IllegalArgumentException - if values is null
or p is invalid
public static double percentile(double[] values,
int begin,
int length,
double p)
pth percentile of the values
in the values array, starting with the element in (0-based)
position begin in the array and including length
values.
Double.NaN if length = 0p) values[begin]
if length = 1 IllegalArgumentException if values
is null , begin or length is invalid, or
p is not a valid quantile value (p must be greater than 0
and less than or equal to 100)
See Percentile for
a description of the percentile estimation algorithm used.
values - array of input valuesp - the percentile to computebegin - the first (0-based) element to include in the computationlength - the number of array elements to include
IllegalArgumentException - if the parameters are not valid or the
input array is null
public static double sumDifference(double[] sample1,
double[] sample2)
throws IllegalArgumentException
sample1 - the first arraysample2 - the second array
IllegalArgumentException - if the arrays do not have the same
(positive) length
public static double meanDifference(double[] sample1,
double[] sample2)
throws IllegalArgumentException
sample1 - the first arraysample2 - the second array
IllegalArgumentException - if the arrays do not have the same
(positive) length
public static double varianceDifference(double[] sample1,
double[] sample2,
double meanDifference)
throws IllegalArgumentException
sample1 - the first arraysample2 - the second arraymeanDifference - the mean difference between corresponding entries
IllegalArgumentException - if the arrays do not have the same
length or their common length is less than 2.meanDifference(double[],double[])
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