/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.mahout.ga.watchmaker;
import java.util.List;
import com.google.common.collect.Lists;
import org.uncommons.watchmaker.framework.FitnessEvaluator;
import com.google.common.base.Preconditions;
/** Special Fitness Evaluator that evaluates all the population ones. */
public abstract class STFitnessEvaluator<T> implements FitnessEvaluator<T> {
private final List<Double> evaluations = Lists.newArrayList();
private List<? extends T> population;
@Override
public double getFitness(T candidate, List<? extends T> population) {
// evaluate the population, when needed
if (this.population == null || this.population != population) {
evaluations.clear();
evaluate(population, evaluations);
this.population = population;
}
int index = population.indexOf(candidate);
Preconditions.checkArgument(index != -1, "Candidate is not part of the population");
return evaluations.get(index);
}
protected abstract void evaluate(List<? extends T> population, List<Double> evaluations);
}