Class RandomUtils

java.lang.Object

org.aksw.commons.collections.random.RandomUtils

public class RandomUtils
extends Object

Created by Claus Stadler Date: Oct 9, 2010 Time: 5:43:50 PM Updated by Konrad Höffner 12.8.2011

Constructor Summary

Constructors

Constructor	Description
RandomUtils()

Method Summary

Modifier and Type	Method	Description
static <T> T	randomItem(Iterable<T> iterable, Random random)
static <T> T	randomItem(Collection<T> collection, Random random)
static <T> T[]	randomSample(T[] universe, int n)	Returns a random sample of the given universe.
static <T> Set<T>	randomSampleSet(Collection<T> source, int sampleSize)
static <T> Set<T>	randomSampleSet(Collection<T> source, int sampleSize, Random random)
static <T> void	retainRandomSample(List<T> inout, int sampleSize, Random random)
static <T> void	shuffleRandomSample(List<T> source, Collection<T> out, int sampleSize, Random random)	Extracts a random sample of a specified maximum size from the given collection.
static <T> void	shuffleRemoveRandomSample(List<T> source, Collection<T> out, int sampleSize, Random random)
static <T> Set<T>	shuffleRemoveRandomSampleSet(List<T> source, int sampleSize, Random random)

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

RandomUtils

public RandomUtils()

Method Details

randomSample

public static <T> T[] randomSample(T[] universe,
 int n)

Returns a random sample of the given universe. If n invalid input: '<'= universe.length, then Arrays.copyOf of the universe is returned. The implementation runs in O(n). Principally the same as the method shuffleRandomSample() but works on arrays, does not shuffle the source, is not a void method and has a better complexity. For a discussion and benchmark of various methods of creating random samples see http://www.java-forum.org/mathematik/116289-random-sample.html

shuffleRandomSample

public static <T> void shuffleRandomSample(List<T> source,
 Collection<T> out,
 int sampleSize,
 Random random)

Extracts a random sample of a specified maximum size from the given collection. Warning: Shuffles elements of the source list.

Type Parameters:

T -

Parameters:

source -

sampleSize -

shuffleRemoveRandomSample

public static <T> void shuffleRemoveRandomSample(List<T> source,
 Collection<T> out,
 int sampleSize,
 Random random)

retainRandomSample

public static <T> void retainRandomSample(List<T> inout,
 int sampleSize,
 Random random)

randomSampleSet

public static <T> Set<T> randomSampleSet(Collection<T> source,
 int sampleSize,
 Random random)

randomSampleSet

public static <T> Set<T> randomSampleSet(Collection<T> source,
 int sampleSize)

shuffleRemoveRandomSampleSet

public static <T> Set<T> shuffleRemoveRandomSampleSet(List<T> source,
 int sampleSize,
 Random random)

randomItem

public static <T> T randomItem(Collection<T> collection,
 Random random)

randomItem

public static <T> T randomItem(Iterable<T> iterable,
 Random random)