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Scalable machine learning libraries
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.mahout.common.mapreduce;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.mahout.math.RandomAccessSparseVector;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;
import java.io.IOException;
public class TransposeMapper extends Mapper {
public static final String NEW_NUM_COLS_PARAM = TransposeMapper.class.getName() + ".newNumCols";
private int newNumCols;
@Override
protected void setup(Context ctx) throws IOException, InterruptedException {
newNumCols = ctx.getConfiguration().getInt(NEW_NUM_COLS_PARAM, Integer.MAX_VALUE);
}
@Override
protected void map(IntWritable r, VectorWritable v, Context ctx) throws IOException, InterruptedException {
int row = r.get();
for (Vector.Element e : v.get().nonZeroes()) {
RandomAccessSparseVector tmp = new RandomAccessSparseVector(newNumCols, 1);
tmp.setQuick(row, e.get());
r.set(e.index());
ctx.write(r, new VectorWritable(tmp));
}
}
}
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