org.jgrapht.experimental.permutation.CollectionPermutationIter Maven / Gradle / Ivy
/* ==========================================
* JGraphT : a free Java graph-theory library
* ==========================================
*
* Project Info: http://jgrapht.sourceforge.net/
* Project Creator: Barak Naveh (http://sourceforge.net/users/barak_naveh)
*
* (C) Copyright 2003-2008, by Barak Naveh and Contributors.
*
* This program and the accompanying materials are dual-licensed under
* either
*
* (a) the terms of the GNU Lesser General Public License version 2.1
* as published by the Free Software Foundation, or (at your option) any
* later version.
*
* or (per the licensee's choosing)
*
* (b) the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation.
*/
/* -----------------
* CollectionPermutationIter.java
* -----------------
* (C) Copyright 2005-2008, by Assaf Lehr and Contributors.
*
* Original Author: Assaf Lehr
* Contributor(s): -
*
* $Id$
*
* Changes
* -------
*/
package org.jgrapht.experimental.permutation;
import java.util.*;
/**
* Given a container with elements (Collection,Enumeration,array) defines a
* permutation iterator which returns, on each iteration, a differnt permutation
* of the source container. You may choose a different container
* type(Collection/Array/etc) for each next call. It will continue as if they
* were the same iterator.
*
* @author Assaf
* @since May 20, 2005
*/
public class CollectionPermutationIter
{
private ArrayPermutationsIter permOrder;
private List sourceArray;
/**
* change everry calculation.can be retrieved publicly
*/
private int [] currPermutationArray;
/**
* Note: the Set interface does not guarantee iteration order. This method
* iterates on the set to get the initial order and after that the data will
* be saved internally in another (ordered) container. So, remeber that the
* Initial order can be different from the objectSet.toString() method. If
* you want it to be the same, use a LinkedHashSet , or use the array
* constructor.
*
* @param objectsSet
*/
public CollectionPermutationIter(Set objectsSet)
{
this(
new ArrayList(objectsSet),
new IntegerPermutationIter(objectsSet.size()));
}
/**
* Uses a permArray like [1,1,1,2] where some of the permutations are not
* relevant. Here there will be 4 permutations (only the '2' position is
* important)
*
* @param objectsArray
*/
public CollectionPermutationIter(List objectsArray)
{
this(
objectsArray,
new IntegerPermutationIter(objectsArray.size()));
}
public CollectionPermutationIter(
List objectsArray,
ArrayPermutationsIter permuter)
{
this.permOrder = permuter;
this.sourceArray = objectsArray;
}
public boolean hasNext()
{
return this.permOrder.hasNextPermutaions();
}
/**
* On first call, returns the source as an array; on any other call
* thereafter, a new permutation
*
* @return null if we overflowed! the array otherwise
*/
public List getNextArray()
{
List permutationResult; // will hold the array result
if (this.permOrder.hasNextPermutaions()) {
this.currPermutationArray = this.permOrder.nextPermutation();
permutationResult = applyPermutation();
} else {
permutationResult = null;
}
return permutationResult;
}
private List applyPermutation()
{
ArrayList output = new ArrayList(sourceArray);
// Example : this.sourceArray = ["A","B","C","D"]
// perOrder: = [ 1 , 0 , 3 , 2 ]
// result : = ["B","A","D","C"]
for (int i = 0; i < output.size(); i++) {
output.set(
i,
this.sourceArray.get(this.currPermutationArray[i]));
}
return output;
}
/**
* Wrap result to a Set.
*
* @return null if we overflowed! the set otherwise
*/
public Set getNextSet()
{
List result = getNextArray();
if (result == null) {
return null;
} else // wrap in a SET
{
Set resultSet = new LinkedHashSet(result);
return resultSet;
}
}
public int [] getCurrentPermutationArray()
{
return this.currPermutationArray;
}
public String toString()
{
StringBuffer sb = new StringBuffer();
sb.append("Permutation int[]=");
sb.append(Arrays.toString(getCurrentPermutationArray()));
List permutationResult = applyPermutation();
sb.append("\nPermutationSet Source Object[]=");
sb.append(this.sourceArray.toString());
sb.append("\nPermutationSet Result Object[]=");
sb.append(permutationResult.toString());
return sb.toString();
}
}
// End CollectionPermutationIter.java