com.ibm.bi.dml.runtime.matrix.sort.ReadWithZeros.java Source code

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Here is the source code for com.ibm.bi.dml.runtime.matrix.sort.ReadWithZeros.java

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/**
 * (C) Copyright IBM Corp. 2010, 2015
 *
 * Licensed 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 com.ibm.bi.dml.runtime.matrix.sort;

import java.io.EOFException;
import java.io.IOException;

import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.IntWritable;

public class ReadWithZeros {

    private boolean contain0s = false;
    private long numZeros = 0;
    private FSDataInputStream currentStream;

    private DoubleWritable keyAfterZero = new DoubleWritable();
    private IntWritable valueAfterZero = new IntWritable();
    private boolean justFound0 = false;

    public ReadWithZeros(FSDataInputStream in, boolean contain0, long num0) {
        currentStream = in;
        contain0s = contain0;
        numZeros = num0;
    }

    public void readNextKeyValuePairs(DoubleWritable readKey, IntWritable readValue) throws IOException {
        try {
            if (contain0s && justFound0) {
                readKey.set(keyAfterZero.get());
                readValue.set(valueAfterZero.get());
                contain0s = false;
            } else {
                readKey.readFields(currentStream);
                readValue.readFields(currentStream);
            }
        } catch (EOFException e) {
            // case in which zero is the maximum value in the matrix. 
            // The zero value from the last entry is not present in the input sorted matrix, but needs to be accounted for.
            if (contain0s && !justFound0) {
                justFound0 = true;
                readKey.set(0);
                readValue.set((int) numZeros);
            } else {
                throw e;
            }
        }

        if (contain0s && !justFound0 && readKey.get() >= 0) {
            justFound0 = true;
            keyAfterZero.set(readKey.get());
            valueAfterZero.set(readValue.get());
            readKey.set(0);
            readValue.set((int) numZeros);
        }
    }
}