/*
* 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.graph.search;
import org.encog.ml.graph.BasicGraph;
import org.encog.ml.graph.BasicNode;
import org.encog.ml.graph.BasicPath;
public class AStarSearch extends AbstractGraphSearch {
private final CostEstimator estimator;
public AStarSearch(BasicGraph theGraph, BasicNode startingPoint,
SearchGoal theGoal, CostEstimator theEstimator) {
super(theGraph, startingPoint, theGoal);
this.estimator = theEstimator;
}
/**
* @return the estimator
*/
public CostEstimator getEstimator() {
return estimator;
}
public double calculatePathCost(BasicPath path) {
double result = 0;
BasicNode lastNode = null;
for(BasicNode node: path.getNodes()) {
double hc = this.estimator.estimateCost(node, getGoal());
double stepCost = 0;
if( lastNode!=null ) {
stepCost = lastNode.getCost(node);
}
result+=(hc+stepCost);
lastNode = node;
}
return result;
}
@Override
public boolean isHigherPriority(BasicPath first, BasicPath second) {
double firstCost = calculatePathCost( first );
double secondCost = calculatePathCost( second );
return firstCost<secondCost;
}
}