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<FONT color="green">001</FONT>    /**<a name="line.1"></a>
<FONT color="green">002</FONT>     * Licensed to the Apache Software Foundation (ASF) under one<a name="line.2"></a>
<FONT color="green">003</FONT>     * or more contributor license agreements.  See the NOTICE file<a name="line.3"></a>
<FONT color="green">004</FONT>     * distributed with this work for additional information<a name="line.4"></a>
<FONT color="green">005</FONT>     * regarding copyright ownership.  The ASF licenses this file<a name="line.5"></a>
<FONT color="green">006</FONT>     * to you under the Apache License, Version 2.0 (the<a name="line.6"></a>
<FONT color="green">007</FONT>     * "License"); you may not use this file except in compliance<a name="line.7"></a>
<FONT color="green">008</FONT>     * with the License.  You may obtain a copy of the License at<a name="line.8"></a>
<FONT color="green">009</FONT>     *<a name="line.9"></a>
<FONT color="green">010</FONT>     *     http://www.apache.org/licenses/LICENSE-2.0<a name="line.10"></a>
<FONT color="green">011</FONT>     *<a name="line.11"></a>
<FONT color="green">012</FONT>     * Unless required by applicable law or agreed to in writing, software<a name="line.12"></a>
<FONT color="green">013</FONT>     * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.13"></a>
<FONT color="green">014</FONT>     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.14"></a>
<FONT color="green">015</FONT>     * See the License for the specific language governing permissions and<a name="line.15"></a>
<FONT color="green">016</FONT>     * limitations under the License.<a name="line.16"></a>
<FONT color="green">017</FONT>     */<a name="line.17"></a>
<FONT color="green">018</FONT>    <a name="line.18"></a>
<FONT color="green">019</FONT>    package org.apache.hadoop.mapreduce.lib.fieldsel;<a name="line.19"></a>
<FONT color="green">020</FONT>    <a name="line.20"></a>
<FONT color="green">021</FONT>    import java.io.IOException;<a name="line.21"></a>
<FONT color="green">022</FONT>    import java.util.ArrayList;<a name="line.22"></a>
<FONT color="green">023</FONT>    import java.util.List;<a name="line.23"></a>
<FONT color="green">024</FONT>    <a name="line.24"></a>
<FONT color="green">025</FONT>    import org.apache.commons.logging.Log;<a name="line.25"></a>
<FONT color="green">026</FONT>    import org.apache.commons.logging.LogFactory;<a name="line.26"></a>
<FONT color="green">027</FONT>    import org.apache.hadoop.classification.InterfaceAudience;<a name="line.27"></a>
<FONT color="green">028</FONT>    import org.apache.hadoop.classification.InterfaceStability;<a name="line.28"></a>
<FONT color="green">029</FONT>    import org.apache.hadoop.conf.Configuration;<a name="line.29"></a>
<FONT color="green">030</FONT>    import org.apache.hadoop.io.Text;<a name="line.30"></a>
<FONT color="green">031</FONT>    import org.apache.hadoop.mapreduce.Reducer;<a name="line.31"></a>
<FONT color="green">032</FONT>    <a name="line.32"></a>
<FONT color="green">033</FONT>    /**<a name="line.33"></a>
<FONT color="green">034</FONT>     * This class implements a reducer class that can be used to perform field<a name="line.34"></a>
<FONT color="green">035</FONT>     * selections in a manner similar to unix cut. <a name="line.35"></a>
<FONT color="green">036</FONT>     * <a name="line.36"></a>
<FONT color="green">037</FONT>     * The input data is treated as fields separated by a user specified<a name="line.37"></a>
<FONT color="green">038</FONT>     * separator (the default value is "\t"). The user can specify a list of<a name="line.38"></a>
<FONT color="green">039</FONT>     * fields that form the reduce output keys, and a list of fields that form<a name="line.39"></a>
<FONT color="green">040</FONT>     * the reduce output values. The fields are the union of those from the key<a name="line.40"></a>
<FONT color="green">041</FONT>     * and those from the value.<a name="line.41"></a>
<FONT color="green">042</FONT>     * <a name="line.42"></a>
<FONT color="green">043</FONT>     * The field separator is under attribute "mapreduce.fieldsel.data.field.separator"<a name="line.43"></a>
<FONT color="green">044</FONT>     * <a name="line.44"></a>
<FONT color="green">045</FONT>     * The reduce output field list spec is under attribute <a name="line.45"></a>
<FONT color="green">046</FONT>     * "mapreduce.fieldsel.reduce.output.key.value.fields.spec". <a name="line.46"></a>
<FONT color="green">047</FONT>     * The value is expected to be like<a name="line.47"></a>
<FONT color="green">048</FONT>     * "keyFieldsSpec:valueFieldsSpec" key/valueFieldsSpec are comma (,) <a name="line.48"></a>
<FONT color="green">049</FONT>     * separated field spec: fieldSpec,fieldSpec,fieldSpec ... Each field spec<a name="line.49"></a>
<FONT color="green">050</FONT>     * can be a simple number (e.g. 5) specifying a specific field, or a range<a name="line.50"></a>
<FONT color="green">051</FONT>     * (like 2-5) to specify a range of fields, or an open range (like 3-) <a name="line.51"></a>
<FONT color="green">052</FONT>     * specifying all the fields starting from field 3. The open range field<a name="line.52"></a>
<FONT color="green">053</FONT>     * spec applies value fields only. They have no effect on the key fields.<a name="line.53"></a>
<FONT color="green">054</FONT>     * <a name="line.54"></a>
<FONT color="green">055</FONT>     * Here is an example: "4,3,0,1:6,5,1-3,7-". It specifies to use fields<a name="line.55"></a>
<FONT color="green">056</FONT>     * 4,3,0 and 1 for keys, and use fields 6,5,1,2,3,7 and above for values.<a name="line.56"></a>
<FONT color="green">057</FONT>     */<a name="line.57"></a>
<FONT color="green">058</FONT>    @InterfaceAudience.Public<a name="line.58"></a>
<FONT color="green">059</FONT>    @InterfaceStability.Stable<a name="line.59"></a>
<FONT color="green">060</FONT>    public class FieldSelectionReducer&lt;K, V&gt;<a name="line.60"></a>
<FONT color="green">061</FONT>        extends Reducer&lt;Text, Text, Text, Text&gt; {<a name="line.61"></a>
<FONT color="green">062</FONT>    <a name="line.62"></a>
<FONT color="green">063</FONT>      private String fieldSeparator = "\t";<a name="line.63"></a>
<FONT color="green">064</FONT>    <a name="line.64"></a>
<FONT color="green">065</FONT>      private String reduceOutputKeyValueSpec;<a name="line.65"></a>
<FONT color="green">066</FONT>    <a name="line.66"></a>
<FONT color="green">067</FONT>      private List&lt;Integer&gt; reduceOutputKeyFieldList = new ArrayList&lt;Integer&gt;();<a name="line.67"></a>
<FONT color="green">068</FONT>    <a name="line.68"></a>
<FONT color="green">069</FONT>      private List&lt;Integer&gt; reduceOutputValueFieldList = new ArrayList&lt;Integer&gt;();<a name="line.69"></a>
<FONT color="green">070</FONT>    <a name="line.70"></a>
<FONT color="green">071</FONT>      private int allReduceValueFieldsFrom = -1;<a name="line.71"></a>
<FONT color="green">072</FONT>    <a name="line.72"></a>
<FONT color="green">073</FONT>      public static final Log LOG = LogFactory.getLog("FieldSelectionMapReduce");<a name="line.73"></a>
<FONT color="green">074</FONT>    <a name="line.74"></a>
<FONT color="green">075</FONT>      public void setup(Context context) <a name="line.75"></a>
<FONT color="green">076</FONT>          throws IOException, InterruptedException {<a name="line.76"></a>
<FONT color="green">077</FONT>        Configuration conf = context.getConfiguration();<a name="line.77"></a>
<FONT color="green">078</FONT>        <a name="line.78"></a>
<FONT color="green">079</FONT>        this.fieldSeparator = <a name="line.79"></a>
<FONT color="green">080</FONT>          conf.get(FieldSelectionHelper.DATA_FIELD_SEPERATOR, "\t");<a name="line.80"></a>
<FONT color="green">081</FONT>        <a name="line.81"></a>
<FONT color="green">082</FONT>        this.reduceOutputKeyValueSpec = <a name="line.82"></a>
<FONT color="green">083</FONT>          conf.get(FieldSelectionHelper.REDUCE_OUTPUT_KEY_VALUE_SPEC, "0-:");<a name="line.83"></a>
<FONT color="green">084</FONT>        <a name="line.84"></a>
<FONT color="green">085</FONT>        allReduceValueFieldsFrom = FieldSelectionHelper.parseOutputKeyValueSpec(<a name="line.85"></a>
<FONT color="green">086</FONT>          reduceOutputKeyValueSpec, reduceOutputKeyFieldList,<a name="line.86"></a>
<FONT color="green">087</FONT>          reduceOutputValueFieldList);<a name="line.87"></a>
<FONT color="green">088</FONT>    <a name="line.88"></a>
<FONT color="green">089</FONT>        LOG.info(FieldSelectionHelper.specToString(fieldSeparator,<a name="line.89"></a>
<FONT color="green">090</FONT>          reduceOutputKeyValueSpec, allReduceValueFieldsFrom,<a name="line.90"></a>
<FONT color="green">091</FONT>          reduceOutputKeyFieldList, reduceOutputValueFieldList));<a name="line.91"></a>
<FONT color="green">092</FONT>      }<a name="line.92"></a>
<FONT color="green">093</FONT>    <a name="line.93"></a>
<FONT color="green">094</FONT>      public void reduce(Text key, Iterable&lt;Text&gt; values, Context context)<a name="line.94"></a>
<FONT color="green">095</FONT>          throws IOException, InterruptedException {<a name="line.95"></a>
<FONT color="green">096</FONT>        String keyStr = key.toString() + this.fieldSeparator;<a name="line.96"></a>
<FONT color="green">097</FONT>        <a name="line.97"></a>
<FONT color="green">098</FONT>        for (Text val : values) {<a name="line.98"></a>
<FONT color="green">099</FONT>          FieldSelectionHelper helper = new FieldSelectionHelper();<a name="line.99"></a>
<FONT color="green">100</FONT>          helper.extractOutputKeyValue(keyStr, val.toString(),<a name="line.100"></a>
<FONT color="green">101</FONT>            fieldSeparator, reduceOutputKeyFieldList,<a name="line.101"></a>
<FONT color="green">102</FONT>            reduceOutputValueFieldList, allReduceValueFieldsFrom, false, false);<a name="line.102"></a>
<FONT color="green">103</FONT>          context.write(helper.getKey(), helper.getValue());<a name="line.103"></a>
<FONT color="green">104</FONT>        }<a name="line.104"></a>
<FONT color="green">105</FONT>      }<a name="line.105"></a>
<FONT color="green">106</FONT>    }<a name="line.106"></a>




























































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