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POHow to store input of input file array in Map Reduce(Java)
 

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  1. POHow to store input of input file array in Map Reduce(Java)
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    <p>I've write Linear Regression Program in java. Input is --> 2,21.05 3,23.51 4,24.23 5,27.71 6,30.86 8,45.85 10,52.12 11,55.98</p> <p>I want store input in array like x[]={2,3,...11} before processing input to reduce task. Then send that array variable to reduce() function But I'm only on value at a time My program.</p> <pre><code>import java.io.DataInput; import java.io.DataOutput; import java.io.IOException; import java.util.ArrayList; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.FloatWritable; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.io.Writable; import org.apache.hadoop.mapreduce.Job; import org.apache.hadoop.mapreduce.Mapper; import org.apache.hadoop.mapreduce.Reducer; import org.apache.hadoop.mapreduce.Reducer.Context; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; public class LinearRegression { public static class RegressionMapper extends Mapper&lt;LongWritable, Text, Text, CountRegression&gt; { private Text id = new Text(); private CountRegression countRegression = new CountRegression(); @Override public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException { String tempString = value.toString(); String[] inputData = tempString.split(","); String xVal = inputData[0]; String yVal = inputData[1]; countRegression.setxVal(Integer.parseInt(xVal)); countRegression.setyVal(Float.parseFloat(yVal)); id.set(xVal); context.write(id, countRegression); } } public static class RegressionReducer extends Reducer&lt;Text, CountRegression, Text, CountRegression&gt; { private CountRegression result = new CountRegression(); // static float meanX = 0; // private float xValues[]; // private float yValues[]; static float xRed = 0.0f; static float yRed = 0.3f; static float sum = 0; static ArrayList&lt;Float&gt; list = new ArrayList&lt;Float&gt;(); public void reduce(Text key, Iterable&lt;CountRegression&gt; values, Context context) throws IOException, InterruptedException { //float b = 0; // while(values.iterator().hasNext()) // { // xRed = xRed + values.iterator().next().getxVal(); // yRed = yRed + values.iterator().next().getyVal(); // } for (CountRegression val : values) { list.add(val.getxVal()); // list.add(val.getyVal()); // xRed += val.getxVal(); // yRed = val.getyVal(); // meanX += val.getxVal(); //xValues = val.getxVal(); } for (int i=0; i&lt; list.size(); i++) { int lastIndex = list.listIterator().previousIndex(); sum += list.get(lastIndex); } result.setxVal(sum); result.setyVal(yRed); context.write(key, result); } } public static class CountRegression implements Writable { private float xVal = 0; private float yVal = 0; public float getxVal() { return xVal; } public void setxVal(float x) { this.xVal = x; } public float getyVal() { return yVal; } public void setyVal(float y) { this.yVal = y; } @Override public void readFields(DataInput in) throws IOException { xVal = in.readFloat(); yVal = in.readFloat(); } @Override public void write(DataOutput out) throws IOException { out.writeFloat(xVal); out.writeFloat(yVal); } @Override public String toString() { return "y = "+xVal+" +"+yVal+" x" ; } } public static void main(String[] args) throws Exception { // Provides access to configuration parameters. Configuration conf = new Configuration(); // Create a new Job It allows the user to configure the job, submit it, control its execution, and query the state. Job job = new Job(conf); //Set the user-specified job name. job.setJobName("LinearRegression"); //Set the Jar by finding where a given class came from. job.setJarByClass(LinearRegression.class); // Set the Mapper for the job. job.setMapperClass(RegressionMapper.class); // Set the Combiner for the job. job.setCombinerClass(RegressionReducer.class); // Set the Reducer for the job. job.setReducerClass(RegressionReducer.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(CountRegression.class); FileInputFormat.setInputPaths(job, new Path(args[0])); FileOutputFormat.setOutputPath(job, new Path(args[1])); System.exit(job.waitForCompletion(true) ? 0 : 1); } } </code></pre>
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    1. PTQuestion
    1. USVijay_Shinde
    1. USVijay_Shinde
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      1. POHow to store input of input file array in Map Reduce(Java)
      1. This table or related slice is empty.
      1. VTDownMod
    2. VO
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      1. POHow to store input of input file array in Map Reduce(Java)
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      1. VTUpMod
    1. COIs this input you describe in one line or `xvalue`,`yvalue``\n``xvalue`,`yvalue` etc. ? What is your `InputFormat`?
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      1. POHow to store input of input file array in Map Reduce(Java)
      1. USArtem Tsikiridis
    2. COyes. its normal text file. x & y seperated by comma & next record to the newline.
      singulars
      1. POHow to store input of input file array in Map Reduce(Java)
      1. USVijay_Shinde
    3. COI can try and help you create a new `InputFormat` but I cannot undestand two things: 1) Why don't you just create an array as a field and `context.write()` only when it's full and 2) The length of `x` how big is it? You cannot store infinite data in memory. So maybe the real question is: "What are you trying to accomplish"? Can you please post `reduce()` and your expected output? Thanks
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      1. POHow to store input of input file array in Map Reduce(Java)
      1. USArtem Tsikiridis
 

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