/**
* 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.tool;
import java.io.IOException;
import java.util.List;
import java.util.regex.Pattern;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
/**
* Extract the attribute values from a dataline. Skip ignored attributes<br>
* Input:<br>
* <ul>
* <li>LongWritable : data row index</li>
* <li>Text : dataline</li>
* </ul>
* Output:<br>
* <ul>
* <li>LongWritable : attribute index.<br>
* ignored attributes aren't taken into account when calculating this index.</li>
* <li>Text : attribute value</li>
* </ul>
*
* See Descriptors, for more information about the job parameter
*/
public class ToolMapper extends Mapper<LongWritable, Text, LongWritable, Text> {
public static final String ATTRIBUTES = "cdtool.attributes";
private static final Pattern COMMA = Pattern.compile(",");
private Descriptors descriptors;
@Override
protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
List<String> attributes = extractAttributes(value);
Preconditions.checkArgument(attributes.size() == descriptors.size(),
"Attributes number should be equal to the descriptors's array length");
// output non ignored attributes
for (int index = 0; index < attributes.size(); index++) {
if (descriptors.isIgnored(index)) {
continue;
}
context.write(new LongWritable(index), new Text(attributes.get(index)));
}
}
@Override
protected void setup(Context context) throws IOException, InterruptedException {
super.setup(context);
String descriptors = context.getConfiguration().get(ATTRIBUTES);
if (descriptors != null) {
configure(descriptors.toCharArray());
}
}
void configure(char[] descriptors) {
Preconditions.checkArgument(descriptors != null && descriptors.length > 0, "descriptors null or empty");
this.descriptors = new Descriptors(descriptors);
}
/**
* Extract attribute values from the input Text. The attributes are separated by a colon ','. Skips ignored
* attributes.
*/
static List<String> extractAttributes(Text value) {
List<String> result = Lists.newArrayList();
for (String token : COMMA.split(value.toString())) {
result.add(token.trim());
}
return result;
}
}