org.apache.mahout.math.RandomMatrix.java Source code

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Here is the source code for org.apache.mahout.math.RandomMatrix.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.math;

import java.util.Map;
import java.util.Random;

import com.google.common.primitives.Longs;

/** 
 * Matrix of random but repeatable doubles. 
 * -Double.MAX_Value -> Double.MAX_VALUE 
 * 
 * Can only use java.util.Random as generator from RandomUtils does not honor setSeed()
 */
public class RandomMatrix extends ReadOnlyMatrix {

    private long baseSeed;
    final private Random rnd = new Random(0);
    final boolean gaussian;

    /**
     * Constructs a zero-size matrix.
     * Some serialization thing?
     */

    public RandomMatrix() {
        cardinality[ROW] = 0;
        cardinality[COL] = 0;
        baseSeed = 0;
        gaussian = false;
    }

    /**
     * Constructs random matrix of the given size.
     * @param rows  The number of rows in the result.
     * @param columns The number of columns in the result.
     * @param baseSeed The starting seed
     * @param .
     * @throws Exception 
     */
    public RandomMatrix(int rows, int columns, long seed, boolean gaussian, Map<String, Integer> rowBindings,
            Map<String, Integer> columnBindings) {
        cardinality[ROW] = rows;
        cardinality[COL] = columns;
        this.baseSeed = seed;
        this.gaussian = gaussian;
        this.rowLabelBindings = rowBindings;
        this.columnLabelBindings = columnBindings;
    }

    @Override
    public double getQuick(int row, int column) {
        if (row < 0 || row >= rowSize())
            throw new CardinalityException(row, rowSize());
        if (column < 0 || column >= columnSize())
            throw new CardinalityException(column, columnSize());
        rnd.setSeed(getSeed(row, column));
        double value = gaussian ? rnd.nextGaussian() : rnd.nextDouble();
        return value;
    }

    private long getSeed(int row, int column) {
        return baseSeed + (row * columnSize()) + column;
    }

    @Override
    public boolean equals(Object o) {
        if (o.getClass() == RandomMatrix.class) {
            RandomMatrix r = (RandomMatrix) o;
            return rowSize() == r.rowSize() && columnSize() == r.columnSize() && baseSeed == r.baseSeed
                    && gaussian == r.gaussian;
        }
        return false;
    }

    @Override
    public int hashCode() {
        return Longs.hashCode(baseSeed)
                ^ Longs.hashCode((rowSize()) ^ Longs.hashCode(columnSize() ^ (gaussian ? 7 : 11)));
    }

}