/*
* SwapOperator.java
*
* Copyright (c) 2002-2015 Alexei Drummond, Andrew Rambaut and Marc Suchard
*
* This file is part of BEAST.
* See the NOTICE file distributed with this work for additional
* information regarding copyright ownership and licensing.
*
* BEAST is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* BEAST is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with BEAST; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301 USA
*/
package dr.inference.operators;
import dr.inference.model.Parameter;
import dr.inferencexml.operators.SwapOperatorParser;
import dr.math.MathUtils;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* A generic operator swapping a number of pairs in a multi-dimensional parameter.
*
* @author Alexei Drummond
* @author Andrew Rambaut
*/
public class SwapOperator extends SimpleMCMCOperator {
private int size = 1;
public SwapOperator(Parameter parameter, int size) {
this.parameter = parameter;
this.size = size;
if (parameter.getDimension() < 2 * size) {
throw new IllegalArgumentException();
}
int dimension = parameter.getDimension();
List<Integer> list = new ArrayList<Integer>();
for (int i = 0; i < dimension; i++) {
list.add(i);
}
masterList = Collections.unmodifiableList(list);
}
/**
* @return the parameter this operator acts on.
*/
public Parameter getParameter() {
return parameter;
}
/**
* swap the values in two random parameter slots.
*/
public final double doOperation() {
List<Integer> allIndices = new ArrayList<Integer>(masterList);
int left, right;
for (int i = 0; i < size; i++) {
left = allIndices.remove(MathUtils.nextInt(allIndices.size()));
right = allIndices.remove(MathUtils.nextInt(allIndices.size()));
double value1 = parameter.getParameterValue(left);
double value2 = parameter.getParameterValue(right);
parameter.setParameterValue(left, value2);
parameter.setParameterValue(right, value1);
}
return 0.0;
}
public String getOperatorName() {
return SwapOperatorParser.SWAP_OPERATOR + "(" + parameter.getParameterName() + ")";
}
public String getPerformanceSuggestion() {
return "No suggestions";
}
//PRIVATE STUFF
private Parameter parameter = null;
private List<Integer> masterList = null;
}