com.ibm.bluej.util.common

Class RandomUtil.Sample<T>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<E>

java.util.ArrayList<T>

com.ibm.bluej.util.common.RandomUtil.Sample<T>

Type Parameters:

T -

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, java.lang.Iterable<T>, java.util.Collection<T>, java.util.List<T>, java.util.RandomAccess

Enclosing class:

RandomUtil

public static class RandomUtil.Sample<T>
extends java.util.ArrayList<T>

A sample of n elements. It is a Collection. uses weighted reservoir sampling http://arxiv.org/pdf/1012.0256.pdf (A-Chao) http://blog.cloudera.com/blog/2013/04/hadoop-stratified-randosampling-algorithm/

Author:

partha

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
RandomUtil.Sample(int sampleSize)

Method Summary

Methods

Modifier and Type	Method and Description
void	maybeSave(T item)
void	maybeSave(T item, double weight) maybeSave(T item, double weight) behaves like two functions: shouldSave and save
void	save(T item) stores the item in the reservoir, ejecting another one if needed
boolean	shouldSave()
boolean	shouldSave(double weight) determines if the item should be stored in the reservoir

Methods inherited from class java.util.ArrayList

add, add, addAll, addAll, clear, clone, contains, ensureCapacity, get, indexOf, isEmpty, iterator, lastIndexOf, listIterator, listIterator, remove, remove, removeAll, retainAll, set, size, subList, toArray, toArray, trimToSize

Methods inherited from class java.util.AbstractList

equals, hashCode

Methods inherited from class java.util.AbstractCollection

containsAll, toString

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.List

containsAll, equals, hashCode

Constructor Detail

RandomUtil.Sample

public RandomUtil.Sample(int sampleSize)

Method Detail

maybeSave

public void maybeSave(T item)

maybeSave

public void maybeSave(T item,
             double weight)

maybeSave(T item, double weight) behaves like two functions: shouldSave and save

Parameters:

item -

weight -

shouldSave

public boolean shouldSave()

shouldSave

public boolean shouldSave(double weight)

determines if the item should be stored in the reservoir

Parameters:

weight -

Returns:

boolean

save

public void save(T item)

stores the item in the reservoir, ejecting another one if needed

Parameters:

item -