/**
* 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.df.ref;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import org.apache.mahout.df.Bagging;
import org.apache.mahout.df.DecisionForest;
import org.apache.mahout.df.builder.TreeBuilder;
import org.apache.mahout.df.callback.PredictionCallback;
import org.apache.mahout.df.data.Data;
import org.apache.mahout.df.node.Node;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Builds a Random Decision Forest using a given TreeBuilder to grow the trees
*/
public class SequentialBuilder {
private static final Logger log = LoggerFactory.getLogger(SequentialBuilder.class);
private final Random rng;
private final Bagging bagging;
/**
* Constructor
*
* @param rng random-numbers generator
* @param treeBuilder tree builder
* @param data training data
*/
public SequentialBuilder(Random rng, TreeBuilder treeBuilder, Data data) {
this.rng = rng;
bagging = new Bagging(treeBuilder, data);
}
public DecisionForest build(int nbTrees, PredictionCallback callback) {
List<Node> trees = new ArrayList<Node>();
for (int treeId = 0; treeId < nbTrees; treeId++) {
trees.add(bagging.build(treeId, rng, callback));
logProgress(((float) treeId + 1) / nbTrees);
}
return new DecisionForest(trees);
}
private static void logProgress(float progress) {
int percent = (int) (progress * 100);
if (percent % 10 == 0)
log.info(String.format("Building %2d%%", percent));
}
}