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//=============================================================================
// Copyright 2006-2010 Daniel W. Dyer
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//=============================================================================
package org.uncommons.watchmaker.examples.monalisa;
import java.awt.Dimension;
import java.awt.Point;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import org.uncommons.maths.number.NumberGenerator;
import org.uncommons.maths.random.Probability;
import org.uncommons.watchmaker.framework.EvolutionaryOperator;
/**
* Base class for mutation operators that modify the points of polygons in an
* image.
* @author Daniel Dyer
*/
abstract class AbstractVertexMutation implements EvolutionaryOperator<ColouredPolygon>
{
private final Dimension canvasSize;
private final NumberGenerator<Probability> mutationProbability;
/**
* @param mutationProbability A {@link NumberGenerator} that controls the probability
* that a polygon's points will be mutated.
* @param canvasSize The size of the canvas. Used to constrain the positions of the points.
*/
protected AbstractVertexMutation(NumberGenerator<Probability> mutationProbability,
Dimension canvasSize)
{
this.mutationProbability = mutationProbability;
this.canvasSize = canvasSize;
}
/**
* @return The dimensions of the target image.
*/
protected Dimension getCanvasSize()
{
return canvasSize;
}
/**
* @return The {@link NumberGenerator} that provides the mutation probability.
*/
protected NumberGenerator<Probability> getMutationProbability()
{
return mutationProbability;
}
/**
* Applies the mutation to each polygon in the list provided according to the
* pre-configured mutation probability. If the probability is 0.1, approximately
* 10% of the individuals will be mutated. The actual mutation operation is
* defined in the sub-class implementation of the
* {@link #mutateVertices(java.util.List, java.util.Random)} method.
* @param polygons The list of polygons to be mutated.
* @param rng A source of randomness.
* @return The polygons after mutation. None, some or all will have been
* modified.
*/
public List<ColouredPolygon> apply(List<ColouredPolygon> polygons, Random rng)
{
List<ColouredPolygon> newPolygons = new ArrayList<ColouredPolygon>(polygons.size());
for (ColouredPolygon polygon : polygons)
{
List<Point> newVertices = mutateVertices(polygon.getVertices(), rng);
newPolygons.add(newVertices == polygon.getVertices()
? polygon
: new ColouredPolygon(polygon.getColour(), newVertices));
}
return newPolygons;
}
/**
* Implemented in sub-classes to perform the mutation of the vertices.
* @param vertices A list of the points that make up the polygon.
* @param rng A source of randomness.
* @return A mutated list of points.
*/
protected abstract List<Point> mutateVertices(List<Point> vertices, Random rng);
}
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