/*
* Encog(tm) Core v3.4 - Java Version
* http://www.heatonresearch.com/encog/
* https://github.com/encog/encog-java-core
* Copyright 2008-2016 Heaton Research, Inc.
*
* 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.
*
* For more information on Heaton Research copyrights, licenses
* and trademarks visit:
* http://www.heatonresearch.com/copyright
*/
package org.encog.ml.prg.species;
import org.encog.ml.prg.EncogProgram;
import org.encog.ml.prg.ProgramNode;
/**
* Compare two Encog programs for speciation. Count the nodes that are the
* different, the higher the compare value, the more different two genomes are.
* Only the opcodes are compared, the actual values are not. This causes the
* comparison to be more about structure than actual values. Two genomes with
* the same structure, and different values, can be identical.
*/
public class CompareEncogProgram {
/**
* Compare program 1 and 2 node for node. Lower values mean more similar genomes.
*
* @param prg1 The first program.
* @param prg2 The second program.
* @return The result of the compare.
*/
public double compare(final EncogProgram prg1, final EncogProgram prg2) {
return compareNode(0, prg1.getRootNode(), prg2.getRootNode());
}
/**
* Compare two nodes.
*
* @param result The result of previous comparisons.
* @param node1 The first node to compare.
* @param node2 The second node to compare.
* @return The result.
*/
private double compareNode(final double result, final ProgramNode node1,
final ProgramNode node2) {
double newResult = result;
if (node1.getTemplate() != node2.getTemplate()) {
newResult++;
}
final int node1Size = node1.getChildNodes().size();
final int node2Size = node2.getChildNodes().size();
final int childNodeCount = Math.max(node1Size, node2Size);
for (int i = 0; i < childNodeCount; i++) {
if (i < node1Size && i < node2Size) {
final ProgramNode childNode1 = node1.getChildNode(i);
final ProgramNode childNode2 = node2.getChildNode(i);
newResult = compareNode(newResult, childNode1, childNode2);
} else {
newResult++;
}
}
return newResult;
}
}