Commons Math example source code file (OpenMapRealMatrix.java)

This example Commons Math source code file (OpenMapRealMatrix.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons Math tags/keywords

abstractrealmatrix, blockrealmatrix, classcastexception, illegalargumentexception, illegalargumentexception, io, matrixindexexception, matrixindexexception, openmaprealmatrix, openmaprealmatrix, override, override, realmatrix, serializable, sparserealmatrix

The Commons Math OpenMapRealMatrix.java source code

/*
 * 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.commons.math.linear;

import java.io.Serializable;

import org.apache.commons.math.util.OpenIntToDoubleHashMap;

/**
 * Sparse matrix implementation based on an open addressed map.
 *
 * @version $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $
 * @since 2.0
 */
public class OpenMapRealMatrix extends AbstractRealMatrix implements SparseRealMatrix, Serializable {

    /** Serializable version identifier. */
    private static final long serialVersionUID = -5962461716457143437L;

    /** Number of rows of the matrix. */
    private final int rows;

    /** Number of columns of the matrix. */
    private final int columns;

    /** Storage for (sparse) matrix elements. */
    private final OpenIntToDoubleHashMap entries;

    /**
     * Build a sparse matrix with the supplied row and column dimensions.
     * @param rowDimension number of rows of the matrix
     * @param columnDimension number of columns of the matrix
     */
    public OpenMapRealMatrix(int rowDimension, int columnDimension) {
        super(rowDimension, columnDimension);
        this.rows    = rowDimension;
        this.columns = columnDimension;
        this.entries = new OpenIntToDoubleHashMap(0.0);
    }

    /**
     * Build a matrix by copying another one.
     * @param matrix matrix to copy
     */
    public OpenMapRealMatrix(OpenMapRealMatrix matrix) {
        this.rows    = matrix.rows;
        this.columns = matrix.columns;
        this.entries = new OpenIntToDoubleHashMap(matrix.entries);
    }

    /** {@inheritDoc} */
    @Override
    public OpenMapRealMatrix copy() {
        return new OpenMapRealMatrix(this);
    }

    /** {@inheritDoc} */
    @Override
    public OpenMapRealMatrix createMatrix(int rowDimension, int columnDimension)
            throws IllegalArgumentException {
        return new OpenMapRealMatrix(rowDimension, columnDimension);
    }

    /** {@inheritDoc} */
    @Override
    public int getColumnDimension() {
        return columns;
    }

    /** {@inheritDoc} */
    @Override
    public OpenMapRealMatrix add(final RealMatrix m)
        throws IllegalArgumentException {
        try {
            return add((OpenMapRealMatrix) m);
        } catch (ClassCastException cce) {
            return (OpenMapRealMatrix) super.add(m);
        }
    }

    /**
     * Compute the sum of this and <code>m.
     *
     * @param m    matrix to be added
     * @return     this + m
     * @throws  IllegalArgumentException if m is not the same size as this
     */
    public OpenMapRealMatrix add(OpenMapRealMatrix m) throws IllegalArgumentException {

        // safety check
        MatrixUtils.checkAdditionCompatible(this, m);

        final OpenMapRealMatrix out = new OpenMapRealMatrix(this);
        for (OpenIntToDoubleHashMap.Iterator iterator = m.entries.iterator(); iterator.hasNext();) {
            iterator.advance();
            final int row = iterator.key() / columns;
            final int col = iterator.key() - row * columns;
            out.setEntry(row, col, getEntry(row, col) + iterator.value());
        }

        return out;

    }

    /** {@inheritDoc} */
    @Override
    public OpenMapRealMatrix subtract(final RealMatrix m)
        throws IllegalArgumentException {
        try {
            return subtract((OpenMapRealMatrix) m);
        } catch (ClassCastException cce) {
            return (OpenMapRealMatrix) super.subtract(m);
        }
    }

    /**
     * Compute this minus <code>m.
     *
     * @param m    matrix to be subtracted
     * @return     this - m
     * @throws  IllegalArgumentException if m is not the same size as this
     */
    public OpenMapRealMatrix subtract(OpenMapRealMatrix m) throws IllegalArgumentException {

        // safety check
        MatrixUtils.checkAdditionCompatible(this, m);

        final OpenMapRealMatrix out = new OpenMapRealMatrix(this);
        for (OpenIntToDoubleHashMap.Iterator iterator = m.entries.iterator(); iterator.hasNext();) {
            iterator.advance();
            final int row = iterator.key() / columns;
            final int col = iterator.key() - row * columns;
            out.setEntry(row, col, getEntry(row, col) - iterator.value());
        }

        return out;

    }

    /** {@inheritDoc} */
    @Override
    public RealMatrix multiply(final RealMatrix m)
        throws IllegalArgumentException {
        try {
            return multiply((OpenMapRealMatrix) m);
        } catch (ClassCastException cce) {

            // safety check
            MatrixUtils.checkMultiplicationCompatible(this, m);

            final int outCols = m.getColumnDimension();
            final BlockRealMatrix out = new BlockRealMatrix(rows, outCols);
            for (OpenIntToDoubleHashMap.Iterator iterator = entries.iterator(); iterator.hasNext();) {
                iterator.advance();
                final double value = iterator.value();
                final int key      = iterator.key();
                final int i        = key / columns;
                final int k        = key % columns;
                for (int j = 0; j < outCols; ++j) {
                    out.addToEntry(i, j, value * m.getEntry(k, j));
                }
            }

            return out;

        }
    }

    /**
     * Returns the result of postmultiplying this by m.
     *
     * @param m    matrix to postmultiply by
     * @return     this * m
     * @throws     IllegalArgumentException
     *             if columnDimension(this) != rowDimension(m)
     */
    public OpenMapRealMatrix multiply(OpenMapRealMatrix m) throws IllegalArgumentException {

        // safety check
        MatrixUtils.checkMultiplicationCompatible(this, m);

        final int outCols = m.getColumnDimension();
        OpenMapRealMatrix out = new OpenMapRealMatrix(rows, outCols);
        for (OpenIntToDoubleHashMap.Iterator iterator = entries.iterator(); iterator.hasNext();) {
            iterator.advance();
            final double value = iterator.value();
            final int key      = iterator.key();
            final int i        = key / columns;
            final int k        = key % columns;
            for (int j = 0; j < outCols; ++j) {
                final int rightKey = m.computeKey(k, j);
                if (m.entries.containsKey(rightKey)) {
                    final int outKey = out.computeKey(i, j);
                    final double outValue =
                        out.entries.get(outKey) + value * m.entries.get(rightKey);
                    if (outValue == 0.0) {
                        out.entries.remove(outKey);
                    } else {
                        out.entries.put(outKey, outValue);
                    }
                }
            }
        }

        return out;

    }

    /** {@inheritDoc} */
    @Override
    public double getEntry(int row, int column) throws MatrixIndexException {
        MatrixUtils.checkRowIndex(this, row);
        MatrixUtils.checkColumnIndex(this, column);
        return entries.get(computeKey(row, column));
    }

    /** {@inheritDoc} */
    @Override
    public int getRowDimension() {
        return rows;
    }

    /** {@inheritDoc} */
    @Override
    public void setEntry(int row, int column, double value)
            throws MatrixIndexException {
        MatrixUtils.checkRowIndex(this, row);
        MatrixUtils.checkColumnIndex(this, column);
        if (value == 0.0) {
            entries.remove(computeKey(row, column));
        } else {
            entries.put(computeKey(row, column), value);
        }
    }

    /** {@inheritDoc} */
    @Override
    public void addToEntry(int row, int column, double increment)
            throws MatrixIndexException {
        MatrixUtils.checkRowIndex(this, row);
        MatrixUtils.checkColumnIndex(this, column);
        final int key = computeKey(row, column);
        final double value = entries.get(key) + increment;
        if (value == 0.0) {
            entries.remove(key);
        } else {
            entries.put(key, value);
        }
    }

    /** {@inheritDoc} */
    @Override
    public void multiplyEntry(int row, int column, double factor)
            throws MatrixIndexException {
        MatrixUtils.checkRowIndex(this, row);
        MatrixUtils.checkColumnIndex(this, column);
        final int key = computeKey(row, column);
        final double value = entries.get(key) * factor;
        if (value == 0.0) {
            entries.remove(key);
        } else {
            entries.put(key, value);
        }
    }

    /**
     * Compute the key to access a matrix element
     * @param row row index of the matrix element
     * @param column column index of the matrix element
     * @return key within the map to access the matrix element
     */
    private int computeKey(int row, int column) {
        return row * columns + column;
    }


}