Mr Implementation--matrix multiplication

1 Importjava.io.IOException;2 Importorg.apache.hadoop.conf.Configuration;3 ImportOrg.apache.hadoop.io.*;4 ImportOrg.apache.hadoop.mapreduce.Job;5 ImportOrg.apache.hadoop.mapreduce.Mapper;6 ImportOrg.apache.hadoop.mapreduce.Reducer;7 ImportOrg.apache.hadoop.mapreduce.lib.input.FileInputFormat;8 ImportOrg.apache.hadoop.mapreduce.lib.input.FileSplit;9 ImportOrg.apache.hadoop.mapreduce.lib.output.FileOutputFormat;Ten ImportOrg.apache.hadoop.fs.Path; One  Public classMatrix { A      Public Static intRowm=0; -      Public Static intColumnm=0; -      Public Static intColumnn=0; the      Public Static classMymapperextendsMapper<object, text, text, text>{ -         PrivateText map_key=NewText (); -         PrivateText map_value=NewText ();  -          Public voidSetup (Context context) { +Configuration conf=context.getconfiguration (); -Columnn=integer.parseint (Conf.get ("ColumnN")); +Rowm=integer.parseint (Conf.get ("ROWM")); A         } at          Public voidMap (Object key,text value,context Context)throwsIOException, interruptedexception{ -Filesplit filesplit=(Filesplit) context.getinputsplit (); -String filename=Filesplit.getpath (). GetName ();  -SYSTEM.OUT.PRINTLN ("Map's data shard length is:" +filesplit.getlength ()); -System.out.println ("The starting position of the data shard is:" +Filesplit.getstart ()); -String[] Templocation=filesplit.getlocations (); in              for(String string:templocation) { -System.out.println ("The host on which the data shard resides is:" +string); to             } +             if(Filename.contains ("M")){             -String[] Tuple=value.tostring (). Split (","); the             intI=integer.parseint (tuple[0]); *String[] Tuples=tuple[1].split ("\ t"); $             intJ=integer.parseint (tuples[0]);Panax Notoginseng             intMij=integer.parseint (tuples[1]); -              for(intK = 1; K <columnn+1; k++) { theMap_key.set (i+ "," +k); +Map_value.set ("M" + "," +j+ "," +mij); A Context.write (Map_key, Map_value);  the             } +             } -             Else if(Filename.contains ("N")){             $String[] Tuple=value.tostring (). Split (","); $                 intJ=integer.parseint (tuple[0]); -String[] Tuples=tuple[1].split ("\ t"); -                 intK=integer.parseint (tuples[0]); the                 intNjk=integer.parseint (tuples[1]); -                  for(inti = 1; I <rowm+1; i++) {WuyiMap_key.set (i+ "," +k); theMap_value.set ("N" + "," +j+ "," +NJK); - Context.write (Map_key, Map_value);  Wu                 }                 -             } About         } $     } -      Public Static classMyreducerextendsReducer<text, text, text, text>{ -         Private intSum=0; -          Public voidSetup (Context context)throwsioexception{ AConfiguration conf=context.getconfiguration (); +Columnm=integer.parseint (Conf.get ("COLUMNM"));  the         } -      Public voidReduce (Text key,iterable<text> value,context Context)throwsioexception,interruptedexception{ $         int[] m=New int[Columnm+1]; the         int[] n=New int[Columnm+1]; theSystem.out.println (key.tostring () + "corresponding value list all values are:"); the          for(Text val:value) { the System.out.println (val.tostring ()); -String[] Tuple=val.tostring (). Split (","); in             if(Tuple[0].equals ("M")){ theM[integer.parseint (Tuple[1])]=integer.parseint (tuple[2]);  the}Else { AboutN[integer.parseint (Tuple[1])]=integer.parseint (tuple[2]);  the             } the         } the          for(intj=1;j<columnm+1;++j) { +sum+=m[j]*N[j]; -         } theContext.write (Key,NewText (integer.tostring (sum)));BayiSum=0;  the     }         the     } -      Public Static voidMain (string[] args)throwsException { -         if(args.length!=3){ theSystem.err.println ("usage:matrixmultiply <inputPathM> <inputPathN> <outputPath>"); theSystem.exit (2); the         } the         Else{ -System.out.println ("M File path:" +args[0]); theString[] Infotuplem=args[0].split ("_"); theRowm=integer.parseint (infotuplem[1]); theColumnm=integer.parseint (infotuplem[2]);94String[] Infotuplen=args[1].split ("_"); theColumnn=integer.parseint (infotuplen[2]);  the         } theConfiguration conf=NewConfiguration ();98Conf.set ("COLUMNM", Integer.tostring (COLUMNM)); AboutConf.set ("Rowm", Integer.tostring (ROWM)); -Conf.set ("ColumnN", Integer.tostring (COLUMNN));101Job job=NewJob (conf, "Matrix");102Job.setjarbyclass (Matrix.class);103Job.setmapperclass (Mymapper.class);104Job.setreducerclass (Myreducer.class); theJob.setoutputkeyclass (Text.class);106Job.setoutputvalueclass (Text.class);107Fileinputformat.setinputpaths (Job,NewPath (Args[0]),NewPath (args[1]));108Fileoutputformat.setoutputpath (Job,NewPath (args[2]));109System.exit (Job.waitforcompletion (true)? 0:1);  the     }111}

The above is the source of the m*n result of the J calculation matrix, the total need three input parameters, namely: The Path of M matrix, the path of n matrix and the input path of the result. Where M is stored in the file, the format of the file is "M_rows_columns", the experimental matrix file is m_300_500. The file of n in the experiment is n_500_700. and the formats in the M and N files are the same, all in the form of "I,j\tmij", where I represents the number of rows of the matrix in which the element is located, J represents the number of columns of the matrix in which the element is located, and mij represents the matrix element. As shown (also in the form of n_500_700):

The matrix is a random number, and the matrix file is generated by the following shell script:

#!/bin/Bash forIinch`seq 1$1` Do     forJinch`seq 1$2`     Dos=$ ($RANDOM% -))            Echo-E"$i, $j \t$s">>m_$1_$2     Done Done

2) The output form of map:

Suppose M is a matrix of i*j, and N is the matrix of j*k.

For M-matrices: The output form of map is (<i,k>,< "M",j,mij>), where <i,k> is key,< "M",j,mij> is value.

M indicates that this key-value pair is the content of the M-matrix

Mij is an element in the M-matrix

I and J are the positions of this element in the matrix.

K is the number of columns of matrix n

Mr Implementation--matrix multiplication