org.apache.mahout.utils.ConcatenateVectorsReducer.java Source code

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Here is the source code for org.apache.mahout.utils.ConcatenateVectorsReducer.java

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/**
 * 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.utils;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.math.NamedVector;
import org.apache.mahout.math.SequentialAccessSparseVector;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;

import com.google.common.base.Preconditions;

/*
 * Moded combiner/reducer. If vector comes in as length A or length B, concatenated.
 * If it is length A + B, combiner has already concatenated.
 * 
 */

public class ConcatenateVectorsReducer extends Reducer<IntWritable, VectorWritable, IntWritable, VectorWritable> {

    int dimsA = 0;
    int dimsB = 0;

    public ConcatenateVectorsReducer() {

    }

    public void setup(Context context) throws java.io.IOException, InterruptedException {
        Configuration configuration = context.getConfiguration();

        dimsA = Integer.valueOf(configuration.getStrings(ConcatenateVectorsJob.MATRIXA_DIMS)[0]);
        dimsB = Integer.valueOf(configuration.getStrings(ConcatenateVectorsJob.MATRIXB_DIMS)[0]);
    }

    public void reduce(IntWritable row, Iterable<VectorWritable> vectorWritableIterable, Context ctx)
            throws java.io.IOException, InterruptedException {
        Vector vA = null;
        Vector vB = null;
        Vector vOut = null;
        boolean isNamed = false;
        String name = null;

        for (VectorWritable vw : vectorWritableIterable) {
            Vector v = vw.get();
            if (v instanceof NamedVector) {
                name = ((NamedVector) v).getName();
                isNamed = true;
            }

            if (v.size() == dimsA) {
                vA = v;
            } else if (v.size() == dimsB) {
                vB = v;
            } else if (v.size() == dimsA + dimsB) {
                vOut = v;
                break;
            }
        }

        Preconditions.checkArgument((vA != null || vB != null) || (vOut != null));

        if (vOut == null) {
            vOut = new SequentialAccessSparseVector(dimsA + dimsB);
            if (isNamed) {
                vOut = new NamedVector(vOut, name);
            }
        }

        if (vA != null) {
            appendVector(vOut, vA, 0);
        }

        if (vB != null) {
            appendVector(vOut, vB, dimsA);
        }
        ctx.write(row, new VectorWritable(vOut));
    }

    private void appendVector(Vector vOut, Vector vIn, int offset) {
        for (Vector.Element element : vIn.nonZeroes()) {
            vOut.set(element.index() + offset, element.get());
        }
    }
}