/*
* 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 $Id: OpenMapRealMatrix.java 1131229 2011-06-03 20:49:25Z luc $
* @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) {
return new OpenMapRealMatrix(rowDimension, columnDimension);
}
/** {@inheritDoc} */
@Override
public int getColumnDimension() {
return columns;
}
/**
* Compute the sum of this matrix and {@code m}.
*
* @param m Matrix to be added.
* @return {@code this} + {@code m}.
* @throws org.apache.commons.math.exception.DimensionMismatchException
* if {@code m} is not the same size as this matrix.
*/
public OpenMapRealMatrix add(OpenMapRealMatrix m) {
// 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) {
try {
return subtract((OpenMapRealMatrix) m);
} catch (ClassCastException cce) {
return (OpenMapRealMatrix) super.subtract(m);
}
}
/**
* Subtract {@code m} from this matrix.
*
* @param m Matrix to be subtracted.
* @return {@code this} - {@code m}.
* @throws org.apache.commons.math.exception.DimensionMismatchException
* if {@code m} is not the same size as this matrix.
*/
public OpenMapRealMatrix subtract(OpenMapRealMatrix m) {
// 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) {
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;
}
}
/**
* Postmultiply this matrix by {@code m}.
*
* @param m Matrix to postmultiply by.
* @return {@code this} * {@code m}.
* @throws MatrixDimensionMismatchException
* if the number of rows of {@code m} differ from the number of columns
* of this matrix.
*/
public OpenMapRealMatrix multiply(OpenMapRealMatrix m) {
// 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) {
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) {
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) {
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) {
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;
}
}