org.matheclipse.core.generic.combinatoric

Class KPartitionsIterable

java.lang.Object

org.matheclipse.core.generic.combinatoric.KPartitionsIterable

All Implemented Interfaces:

java.lang.Iterable<int[]>, java.util.Iterator<int[]>

public class KPartitionsIterable
extends java.lang.Object
implements java.util.Iterator<int[]>, java.lang.Iterable<int[]>

This class returns the indexes for partitioning a list of N elements.
Usage pattern:

 final KPartitionsIterable iter = new KPartitionsIterable(n, k);
 for (int[] partitionsIndex : iter) {
   ...
 }
 

Example: KPartitionsIterable(3,5) gives the following sequences [0, 1, 2], [0, 1, 3], [0, 1, 4], [0, 2, 3], [0, 2, 4], [0, 3, 4]
If you interpret these integer lists as indexes for a list {a,b,c,d,e} which should be partitioned into 3 parts the results are:
{{{a},{b},{c,d,e}}, {{a},{b,c},{d,e}}, {{a},{b,c,d},{e}}, {{a,b},{c},{d,e}}, {{a,b},{c,d},{e}}, {{a,b,c},{d},{e}}}

See Wikipedia - Partition of a set

Constructor Summary

Constructors

Constructor and Description
KPartitionsIterable(int length, int parts)

Method Summary

Modifier and Type	Method and Description
boolean	hasNext()
java.util.Iterator<int[]>	iterator()
int[]	next() Get the index array for the next partition.
void	remove()
void	reset()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

forEachRemaining

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

KPartitionsIterable

public KPartitionsIterable(int length,
                           int parts)

Method Detail

reset

public final void reset()

next

public int[] next()

Get the index array for the next partition.

Specified by:

next in interface java.util.Iterator<int[]>

Returns:

null if no further index array could be generated

hasNext

public boolean hasNext()

Specified by:

hasNext in interface java.util.Iterator<int[]>

remove

public void remove()

Specified by:

remove in interface java.util.Iterator<int[]>

iterator

public java.util.Iterator<int[]> iterator()

Specified by:

iterator in interface java.lang.Iterable<int[]>