/**
* 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.cd.hadoop;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reporter;
import org.apache.mahout.ga.watchmaker.cd.CDFitness;
import org.apache.mahout.ga.watchmaker.cd.DataLine;
import org.apache.mahout.ga.watchmaker.cd.DataSet;
import org.apache.mahout.ga.watchmaker.cd.Rule;
import org.apache.mahout.common.StringUtils;
import java.io.IOException;
import java.util.List;
/**
* Hadoop Mapper. Evaluate all the rules with the input data line.
*/
public class CDMapper extends MapReduceBase implements
Mapper<LongWritable, Text, LongWritable, CDFitness> {
public static final String CLASSDISCOVERY_RULES = "mahout.ga.classdiscovery.rules";
public static final String CLASSDISCOVERY_DATASET = "mahout.ga.classdiscovery.dataset";
public static final String CLASSDISCOVERY_TARGET_LABEL = "mahout.ga.classdiscovery.target";
private List<Rule> rules;
private int target;
@Override
@SuppressWarnings("unchecked")
public void configure(JobConf job) {
String rstr = job.get(CLASSDISCOVERY_RULES);
if (rstr == null)
throw new IllegalArgumentException("Job Parameter (" + CLASSDISCOVERY_RULES
+ ") not found!");
String datastr = job.get(CLASSDISCOVERY_DATASET);
if (datastr == null)
throw new IllegalArgumentException("Job Parameter (" + CLASSDISCOVERY_DATASET
+ ") not found!");
int target = job.getInt(CLASSDISCOVERY_TARGET_LABEL, -1);
if (target == -1)
throw new IllegalArgumentException("Job Parameter ("
+ CLASSDISCOVERY_TARGET_LABEL + ") not found!");
initializeDataSet((DataSet) StringUtils.fromString(datastr));
configure((List<Rule>) StringUtils.fromString(rstr), target);
super.configure(job);
}
static void initializeDataSet(DataSet dataset) {
if (dataset == null) {
throw new IllegalArgumentException("bad 'dataset' configuration parameter");
}
DataSet.initialize(dataset);
}
void configure(List<Rule> rules, int target) {
if (!(rules != null && !rules.isEmpty())) {
throw new IllegalArgumentException("bad 'rules' configuration parameter");
}
if (target < 0) {
throw new IllegalArgumentException("bad 'target' configuration parameter");
}
this.rules = rules;
this.target = target;
}
@Override
public void map(LongWritable key, Text value,
OutputCollector<LongWritable, CDFitness> output, Reporter reporter)
throws IOException {
DataLine dl = new DataLine(value.toString());
map(key, dl, output);
}
void map(LongWritable key, DataLine dl,
OutputCollector<LongWritable, CDFitness> output) throws IOException {
for (int index = 0; index < rules.size(); index++) {
CDFitness eval = evaluate(target, rules.get(index).classify(dl), dl
.getLabel());
output.collect(new LongWritable(index), eval);
}
}
/**
* Evaluate a given prediction.
*
* @param target expected label
* @param prediction
* @param label actual label
*/
public static CDFitness evaluate(int target, int prediction, int label) {
int tp = (label == target && prediction == 1) ? 1 : 0;
int fp = (label != target && prediction == 1) ? 1 : 0;
int tn = (label != target && prediction == 0) ? 1 : 0;
int fn = (label == target && prediction == 0) ? 1 : 0;
return new CDFitness(tp, fp, tn, fn);
}
}