Package edu.cmu.tetrad.util

Class SublistGenerator

java.lang.Object

edu.cmu.tetrad.util.SublistGenerator

public final class SublistGenerator
extends Object

Generates (nonrecursively) all of the sublists of size b from a list of size a, where a, b are nonnegative integers and a >= b. The values of a and b are given in the constructor, and the sequence of sublists is obtained by repeatedly calling the next() method. When the sequence is finished, null is returned.

A valid combination for the sublists generated by this class is an array x[] of b integers i, 0 <= i < a, such that x[j] < x[j + 1] for each j from 0 to b - 1.

Works by calling ChoiceGenerator with increasingly larger values of a.

To see what this class does, try calling ChoiceGenerator.testPrint(5, 3), for instance.

Version:

$Id: $Id

Author:

josephramsey

Constructor Summary

Constructors

Constructor	Description
SublistGenerator(int a, int depth)	Constructs a new generator for sublists for a list of size b taken a at a time.

Method Summary

Modifier and Type	Method	Description
int	getA()	Getter for the field a.
static int	getNumCombinations(int a, int b)	getNumCombinations.
int[]	next()	next.
static void	testPrint(int a, int depth)	This static method will print the series of combinations for a choose depth to System.out.
String	toString()	toString.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

SublistGenerator

public SublistGenerator(int a,
 int depth)

Constructs a new generator for sublists for a list of size b taken a at a time. Once this initialization has been performed, successive calls to next() will produce the series of combinations. To begin a new series at any time, call this init method again with new values for a and b.

Parameters:

a - the size of the list being selected from.

depth - the maximum number of elements selected.

Method Details

getNumCombinations

public static int getNumCombinations(int a,
 int b)

getNumCombinations.

Parameters:

a - a int

b - a int

Returns:

a int

testPrint

public static void testPrint(int a,
 int depth)

This static method will print the series of combinations for a choose depth to System.out.

Parameters:

a - the number of objects being selected from.

depth - the number of objects in the desired selection.

next

public int[] next()

next.

Returns:

the next combination in the series, or null if the series is finished.

toString

public String toString()

toString.

Overrides:

toString in class Object

Returns:

a String object

getA

public int getA()

Getter for the field a.

Returns:

Ibid.