[Hama Wiki] Trivial Update of "MatMult" by udanax

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The "MatMult" page has been changed by udanax.
http://wiki.apache.org/hama/MatMult?action=diff&rev1=13&rev2=14

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    }
  }}}
  
+ == Multiplication of file matrices ==
+ 
+ {{{
+  public static void main(String[] args) throws IOException {
+     collectBlocksFromFile(path[0], true, collectionTable, conf); // path of matrix A
+     collectBlocksFromFile(path[1], false, collectionTable, conf); // path of matrix B 
+ 
+     Matrix result = new DenseMatrix(conf, 4, 4);
+     Job job = new Job(conf, "multiplication MR job : " + result.getPath());
+ 
+     Scan scan = new Scan();
+     scan.addFamily(Bytes.toBytes(Constants.BLOCK));
+ 
+     TableMapReduceUtil.initTableMapperJob(collectionTable, scan,
+         BlockMultMap.class, BlockID.class, BytesWritable.class, job);
+     TableMapReduceUtil.initTableReducerJob(result.getPath(),
+         BlockMultReduce.class, job);
+ 
+     try {
+       job.waitForCompletion(true);
+     } catch (InterruptedException e) {
+       e.printStackTrace();
+     } catch (ClassNotFoundException e) {
+       e.printStackTrace();
+     }
+   }
+ 
+   private static void collectBlocksFromFile(Path path, boolean b,
+       String collectionTable, HamaConfiguration conf) throws IOException {
+     Job job = new Job(conf, "Blocking MR job" + path);
+     job.setMapperClass(MyMapper.class);
+     job.setMapOutputKeyClass(BlockID.class);
+     job.setMapOutputValueClass(MapWritable.class);
+     job.setInputFormatClass(SequenceFileInputFormat.class);
+     SequenceFileInputFormat.addInputPath(job, path);
+ 
+     job.getConfiguration().set(MyMapper.BLOCK_SIZE, String.valueOf(2));
+     job.getConfiguration().set(MyMapper.ROWS, String.valueOf(4));
+     job.getConfiguration().set(MyMapper.COLUMNS, String.valueOf(4));
+     job.getConfiguration().setBoolean(MyMapper.MATRIX_POS, b);
+     
+     TableMapReduceUtil.initTableReducerJob(collectionTable,
+         org.apache.hama.mapreduce.CollectBlocksReducer.class, job);
+ 
+     try {
+       job.waitForCompletion(true);
+     } catch (InterruptedException e) {
+       e.printStackTrace();
+     } catch (ClassNotFoundException e) {
+       e.printStackTrace();
+     }
+   }
+ 
+   public static class MyMapper extends
+       Mapper<IntWritable, MapWritable, BlockID, MapWritable> implements
+       Configurable {
+     private Configuration conf = null;
+     /** Parameter of the path of the matrix to be blocked * */
+     public static final String BLOCK_SIZE = "hama.blocking.size";
+     public static final String ROWS = "hama.blocking.rows";
+     public static final String COLUMNS = "hama.blocking.columns";
+     public static final String MATRIX_POS = "a.or.b";
+ 
+     private int mBlockNum;
+     private int mBlockRowSize;
+     private int mBlockColSize;
+     private int mRows;
+     private int mColumns;
+ 
+     public void map(IntWritable key, MapWritable value, Context context)
+         throws IOException, InterruptedException {
+       int startColumn, endColumn, blkRow = key.get() / mBlockRowSize, i = 0;
+       DenseVector dv = new DenseVector(key.get(), value);
+ 
+       do {
+         startColumn = i * mBlockColSize;
+         endColumn = startColumn + mBlockColSize - 1;
+         if (endColumn >= mColumns) // the last sub vector
+           endColumn = mColumns - 1;
+         context.write(new BlockID(blkRow, i), dv.subVector(startColumn,
+             endColumn).getEntries());
+ 
+         i++;
+       } while (endColumn < (mColumns - 1));
+     }
+ 
+     @Override
+     public Configuration getConf() {
+       return conf;
+     }
+ 
+     @Override
+     public void setConf(Configuration conf) {
+       this.conf = conf;
+ 
+       mBlockNum = conf.getInt(BLOCK_SIZE, 2);
+       mRows = conf.getInt(ROWS, 4);
+       mColumns = conf.getInt(COLUMNS, 4);
+ 
+       mBlockRowSize = mRows / mBlockNum;
+       mBlockColSize = mColumns / mBlockNum;
+     }
+   }
+ }}}
+