StringAttrStats.java

/*
 * chombo: Hadoop Map Reduce utility
 * Author: Pranab Ghosh
 * 
 * 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.
 */


package org.chombo.mr;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.chombo.util.GenericAttributeSchema;
import org.chombo.util.Tuple;
import org.chombo.util.Utility;
import org.chombo.util.Attribute;

/**
 * Basic stats for length of string attributes
 * @author pranab
 *
 */
public class StringAttrStats extends Configured implements Tool {
	private static String configDelim = ",";

	@Override
	public int run(String[] args) throws Exception {
        Job job = new Job(getConf());
        String jobName = "Basic stats for string attribute lengths";
        job.setJobName(jobName);
        
        job.setJarByClass(StringAttrStats.class);

        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        Utility.setConfiguration(job.getConfiguration(), "chombo");
        job.setMapperClass(StringAttrStats.StatsMapper.class);
        job.setReducerClass(NumericalAttrStats.StatsReducer.class);
        job.setCombinerClass(NumericalAttrStats.StatsCombiner.class);
        
        job.setMapOutputKeyClass(Tuple.class);
        job.setMapOutputValueClass(Tuple.class);

        job.setOutputKeyClass(NullWritable.class);
        job.setOutputValueClass(Text.class);

        int numReducer = job.getConfiguration().getInt("sas.num.reducer", -1);
        numReducer = -1 == numReducer ? job.getConfiguration().getInt("num.reducer", 1) : numReducer;
        job.setNumReduceTasks(numReducer);

        int status =  job.waitForCompletion(true) ? 0 : 1;
        return status;
	}

	/**
	 * @author pranab
	 *
	 */
	public static class StatsMapper extends Mapper<LongWritable, Text, Tuple, Tuple> {
		private Tuple outKey = new Tuple();
		private Tuple outVal = new Tuple();
		private int[]  attributes;
        private String fieldDelimRegex;
        private double val;
        private double sqVal;
        private int count = 1;
        private String[] items;
        private int[] idOrdinals;
        private GenericAttributeSchema schema;
                
        protected void setup(Context context) throws IOException, InterruptedException {
        	Configuration config = context.getConfiguration();
        	fieldDelimRegex = config.get("field.delim.regex", ",");
        	schema = Utility.getGenericAttributeSchema(config,  "sas.schema.file.path");
            attributes = Utility.getAttributes("sas.attr.list", configDelim,  schema, config,  Attribute.DATA_TYPE_STRING);        	
        	idOrdinals = Utility.intArrayFromString(config.get("sas.id.field.ordinals"), configDelim);
       }

        @Override
        protected void map(LongWritable key, Text value, Context context)
            throws IOException, InterruptedException {
            items  =  value.toString().split(fieldDelimRegex, -1);
        	for (int attr : attributes) {
            	outKey.initialize();
            	outVal.initialize();
            	
            	if (null != idOrdinals) {
            		outKey.addFromArray(items, idOrdinals);
            	}
            	outKey.add(attr);
            	
            	val = items[attr].length();
            	sqVal = val * val;
            	outVal.add(val, val, val, sqVal, count);
            	context.write(outKey, outVal);
        	}
        }
	}
	
	
	/**
	 * @param args
	 */
	public static void main(String[] args) throws Exception {
        int exitCode = ToolRunner.run(new StringAttrStats(), args);
        System.exit(exitCode);
	}
	
}