Class Median
- java.lang.Object
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- org.apache.commons.statistics.descriptive.Median
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public final class Median extends Object
Returns the median of the available values.For values of length
n, letk = n / 2:- The result is
NaNifn = 0. - The result is
values[k]ifnis odd. - The result is
(values[k - 1] + values[k]) / 2ifnis even.
This implementation respects the ordering imposed by
Double.compare(double, double)forNaNvalues. If aNaNoccurs in the selected positions in the fully sorted values then the result isNaN.The
NaNPolicycan be used to change the behaviour onNaNvalues.Instances of this class are immutable and thread-safe.
- Since:
- 1.1
- See Also:
with(NaNPolicy), Median (Wikipedia)
- The result is
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description doubleevaluate(double[] values)Evaluate the median.doubleevaluate(int[] values)Evaluate the median.Medianwith(NaNPolicy v)Return an instance with the configuredNaNPolicy.MedianwithCopy(boolean v)Return an instance with the configured copy behaviour.static MedianwithDefaults()Return a new instance with the default options.
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Method Detail
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withDefaults
public static Median withDefaults()
Return a new instance with the default options.Note: The default options configure for processing in-place and including
NaNvalues in the data. This is the most efficient mode and has the smallest memory consumption.- Returns:
- the median implementation
- See Also:
withCopy(boolean),with(NaNPolicy)
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withCopy
public Median withCopy(boolean v)
Return an instance with the configured copy behaviour. Iffalsethen the input array will be modified by the call to evaluate the median; otherwise the computation uses a copy of the data.- Parameters:
v- Value.- Returns:
- an instance
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with
public Median with(NaNPolicy v)
Return an instance with the configuredNaNPolicy.Note: This implementation respects the ordering imposed by
Double.compare(double, double)forNaNvalues:NaNis considered greater than all other values, and allNaNvalues are equal. TheNaNPolicychanges the computation of the statistic in the presence ofNaNvalues.NaNPolicy.INCLUDE:NaNvalues are moved to the end of the data; the size of the data includes theNaNvalues and the median will beNaNif any value used for median interpolation isNaN.NaNPolicy.EXCLUDE:NaNvalues are moved to the end of the data; the size of the data excludes theNaNvalues and the median will never beNaNfor non-zero size. If all data areNaNthen the size is zero and the result isNaN.NaNPolicy.ERROR: An exception is raised if the data containsNaNvalues.
Note that the result is identical for all policies if no
NaNvalues are present.- Parameters:
v- Value.- Returns:
- an instance
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evaluate
public double evaluate(double[] values)
Evaluate the median.Note: This method may partially sort the input values if not configured to
copythe input data.- Parameters:
values- Values.- Returns:
- the median
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