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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.commons.math.linear;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Array;
import java.math.BigDecimal;
import java.util.Arrays;
import org.apache.commons.math.Field;
import org.apache.commons.math.FieldElement;
import org.apache.commons.math.MathRuntimeException;
import org.apache.commons.math.exception.util.LocalizedFormats;
import org.apache.commons.math.fraction.BigFraction;
import org.apache.commons.math.fraction.Fraction;
/**
* A collection of static methods that operate on or return matrices.
*
* @version $Revision: 983921 $ $Date: 2010-08-10 12:46:06 +0200 (mar. 10 août 2010) $
*/
public class MatrixUtils {
/**
* Private constructor.
*/
private MatrixUtils() {
super();
}
/**
* Returns a {@link RealMatrix} with specified dimensions.
* The type of matrix returned depends on the dimension. Below
* 212 elements (i.e. 4096 elements or 64×64 for a
* square matrix) which can be stored in a 32kB array, a {@link
* Array2DRowRealMatrix} instance is built. Above this threshold a {@link
* BlockRealMatrix} instance is built.
* The matrix elements are all set to 0.0.
* @param rows number of rows of the matrix
* @param columns number of columns of the matrix
* @return RealMatrix with specified dimensions
* @see #createRealMatrix(double[][])
*/
public static RealMatrix createRealMatrix(final int rows, final int columns) {
return (rows * columns <= 4096) ?
new Array2DRowRealMatrix(rows, columns) : new BlockRealMatrix(rows, columns);
}
/**
* Returns a {@link FieldMatrix} with specified dimensions.
* The type of matrix returned depends on the dimension. Below
* 212 elements (i.e. 4096 elements or 64×64 for a
* square matrix), a {@link FieldMatrix} instance is built. Above
* this threshold a {@link BlockFieldMatrix} instance is built.
* The matrix elements are all set to field.getZero().
* @param the type of the field elements
* @param field field to which the matrix elements belong
* @param rows number of rows of the matrix
* @param columns number of columns of the matrix
* @return FieldMatrix with specified dimensions
* @see #createFieldMatrix(FieldElement[][])
* @since 2.0
*/
public static > FieldMatrix createFieldMatrix(final Field field,
final int rows,
final int columns) {
return (rows * columns <= 4096) ?
new Array2DRowFieldMatrix(field, rows, columns) : new BlockFieldMatrix(field, rows, columns);
}
/**
* Returns a {@link RealMatrix} whose entries are the the values in the
* the input array.
* The type of matrix returned depends on the dimension. Below
* 212 elements (i.e. 4096 elements or 64×64 for a
* square matrix) which can be stored in a 32kB array, a {@link
* Array2DRowRealMatrix} instance is built. Above this threshold a {@link
* BlockRealMatrix} instance is built.
* The input array is copied, not referenced.
*
* @param data input array
* @return RealMatrix containing the values of the array
* @throws IllegalArgumentException if data is not rectangular
* (not all rows have the same length) or empty
* @throws NullPointerException if either data or
* data[0] is null
* @see #createRealMatrix(int, int)
*/
public static RealMatrix createRealMatrix(double[][] data) {
return (data.length * data[0].length <= 4096) ?
new Array2DRowRealMatrix(data) : new BlockRealMatrix(data);
}
/**
* Returns a {@link FieldMatrix} whose entries are the the values in the
* the input array.
* The type of matrix returned depends on the dimension. Below
* 212 elements (i.e. 4096 elements or 64×64 for a
* square matrix), a {@link FieldMatrix} instance is built. Above
* this threshold a {@link BlockFieldMatrix} instance is built.
* The input array is copied, not referenced.
* @param the type of the field elements
* @param data input array
* @return RealMatrix containing the values of the array
* @throws IllegalArgumentException if data is not rectangular
* (not all rows have the same length) or empty
* @throws NullPointerException if either data or
* data[0] is null
* @see #createFieldMatrix(Field, int, int)
* @since 2.0
*/
public static > FieldMatrix createFieldMatrix(T[][] data) {
return (data.length * data[0].length <= 4096) ?
new Array2DRowFieldMatrix(data) : new BlockFieldMatrix(data);
}
/**
* Returns dimension x dimension identity matrix.
*
* @param dimension dimension of identity matrix to generate
* @return identity matrix
* @throws IllegalArgumentException if dimension is not positive
* @since 1.1
*/
public static RealMatrix createRealIdentityMatrix(int dimension) {
final RealMatrix m = createRealMatrix(dimension, dimension);
for (int i = 0; i < dimension; ++i) {
m.setEntry(i, i, 1.0);
}
return m;
}
/**
* Returns dimension x dimension identity matrix.
*
* @param the type of the field elements
* @param field field to which the elements belong
* @param dimension dimension of identity matrix to generate
* @return identity matrix
* @throws IllegalArgumentException if dimension is not positive
* @since 2.0
*/
public static > FieldMatrix
createFieldIdentityMatrix(final Field field, final int dimension) {
final T zero = field.getZero();
final T one = field.getOne();
@SuppressWarnings("unchecked") // zero is type T
final T[][] d = (T[][]) Array.newInstance(zero.getClass(), new int[] { dimension, dimension });
for (int row = 0; row < dimension; row++) {
final T[] dRow = d[row];
Arrays.fill(dRow, zero);
dRow[row] = one;
}
return new Array2DRowFieldMatrix(d, false);
}
/**
* Returns dimension x dimension identity matrix.
*
* @param dimension dimension of identity matrix to generate
* @return identity matrix
* @throws IllegalArgumentException if dimension is not positive
* @since 1.1
* @deprecated since 2.0, replaced by {@link #createFieldIdentityMatrix(Field, int)}
*/
@Deprecated
public static BigMatrix createBigIdentityMatrix(int dimension) {
final BigDecimal[][] d = new BigDecimal[dimension][dimension];
for (int row = 0; row < dimension; row++) {
final BigDecimal[] dRow = d[row];
Arrays.fill(dRow, BigMatrixImpl.ZERO);
dRow[row] = BigMatrixImpl.ONE;
}
return new BigMatrixImpl(d, false);
}
/**
* Returns a diagonal matrix with specified elements.
*
* @param diagonal diagonal elements of the matrix (the array elements
* will be copied)
* @return diagonal matrix
* @since 2.0
*/
public static RealMatrix createRealDiagonalMatrix(final double[] diagonal) {
final RealMatrix m = createRealMatrix(diagonal.length, diagonal.length);
for (int i = 0; i < diagonal.length; ++i) {
m.setEntry(i, i, diagonal[i]);
}
return m;
}
/**
* Returns a diagonal matrix with specified elements.
*
* @param the type of the field elements
* @param diagonal diagonal elements of the matrix (the array elements
* will be copied)
* @return diagonal matrix
* @since 2.0
*/
public static > FieldMatrix
createFieldDiagonalMatrix(final T[] diagonal) {
final FieldMatrix m =
createFieldMatrix(diagonal[0].getField(), diagonal.length, diagonal.length);
for (int i = 0; i < diagonal.length; ++i) {
m.setEntry(i, i, diagonal[i]);
}
return m;
}
/**
* Returns a {@link BigMatrix} whose entries are the the values in the
* the input array. The input array is copied, not referenced.
*
* @param data input array
* @return RealMatrix containing the values of the array
* @throws IllegalArgumentException if data is not rectangular
* (not all rows have the same length) or empty
* @throws NullPointerException if data is null
* @deprecated since 2.0 replaced by {@link #createFieldMatrix(FieldElement[][])}
*/
@Deprecated
public static BigMatrix createBigMatrix(double[][] data) {
return new BigMatrixImpl(data);
}
/**
* Returns a {@link BigMatrix} whose entries are the the values in the
* the input array. The input array is copied, not referenced.
*
* @param data input array
* @return RealMatrix containing the values of the array
* @throws IllegalArgumentException if data is not rectangular
* (not all rows have the same length) or empty
* @throws NullPointerException if data is null
* @deprecated since 2.0 replaced by {@link #createFieldMatrix(FieldElement[][])}
*/
@Deprecated
public static BigMatrix createBigMatrix(BigDecimal[][] data) {
return new BigMatrixImpl(data);
}
/**
* Returns a {@link BigMatrix} whose entries are the the values in the
* the input array.
* If an array is built specially in order to be embedded in a
* BigMatrix and not used directly, the copyArray may be
* set to false
* @param data data for new matrix
* @param copyArray if true, the input array will be copied, otherwise
* it will be referenced
* @return BigMatrix containing the values of the array
* @throws IllegalArgumentException if data is not rectangular
* (not all rows have the same length) or empty
* @throws NullPointerException if data is null
* @see #createRealMatrix(double[][])
* @deprecated since 2.0 replaced by {@link #createFieldMatrix(FieldElement[][])}
*/
@Deprecated
public static BigMatrix createBigMatrix(BigDecimal[][] data, boolean copyArray) {
return new BigMatrixImpl(data, copyArray);
}
/**
* Returns a {@link BigMatrix} whose entries are the the values in the
* the input array. The input array is copied, not referenced.
*
* @param data input array
* @return RealMatrix containing the values of the array
* @throws IllegalArgumentException if data is not rectangular
* (not all rows have the same length) or empty
* @throws NullPointerException if data is null
* @deprecated since 2.0 replaced by {@link #createFieldMatrix(FieldElement[][])}
*/
@Deprecated
public static BigMatrix createBigMatrix(String[][] data) {
return new BigMatrixImpl(data);
}
/**
* Creates a {@link RealVector} using the data from the input array.
*
* @param data the input data
* @return a data.length RealVector
* @throws IllegalArgumentException if data is empty
* @throws NullPointerException if datais null
*/
public static RealVector createRealVector(double[] data) {
return new ArrayRealVector(data, true);
}
/**
* Creates a {@link FieldVector} using the data from the input array.
*
* @param the type of the field elements
* @param data the input data
* @return a data.length FieldVector
* @throws IllegalArgumentException if data is empty
* @throws NullPointerException if datais null
*/
public static > FieldVector createFieldVector(final T[] data) {
return new ArrayFieldVector(data, true);
}
/**
* Creates a row {@link RealMatrix} using the data from the input
* array.
*
* @param rowData the input row data
* @return a 1 x rowData.length RealMatrix
* @throws IllegalArgumentException if rowData is empty
* @throws NullPointerException if rowDatais null
*/
public static RealMatrix createRowRealMatrix(double[] rowData) {
final int nCols = rowData.length;
final RealMatrix m = createRealMatrix(1, nCols);
for (int i = 0; i < nCols; ++i) {
m.setEntry(0, i, rowData[i]);
}
return m;
}
/**
* Creates a row {@link FieldMatrix} using the data from the input
* array.
*
* @param the type of the field elements
* @param rowData the input row data
* @return a 1 x rowData.length FieldMatrix
* @throws IllegalArgumentException if rowData is empty
* @throws NullPointerException if rowDatais null
*/
public static > FieldMatrix
createRowFieldMatrix(final T[] rowData) {
final int nCols = rowData.length;
if (nCols == 0) {
throw MathRuntimeException.createIllegalArgumentException(LocalizedFormats.AT_LEAST_ONE_COLUMN);
}
final FieldMatrix m = createFieldMatrix(rowData[0].getField(), 1, nCols);
for (int i = 0; i < nCols; ++i) {
m.setEntry(0, i, rowData[i]);
}
return m;
}
/**
* Creates a row {@link BigMatrix} using the data from the input
* array.
*
* @param rowData the input row data
* @return a 1 x rowData.length BigMatrix
* @throws IllegalArgumentException if rowData is empty
* @throws NullPointerException if rowDatais null
* @deprecated since 2.0 replaced by {@link #createRowFieldMatrix(FieldElement[])}
*/
@Deprecated
public static BigMatrix createRowBigMatrix(double[] rowData) {
final int nCols = rowData.length;
final BigDecimal[][] data = new BigDecimal[1][nCols];
for (int i = 0; i < nCols; ++i) {
data[0][i] = new BigDecimal(rowData[i]);
}
return new BigMatrixImpl(data, false);
}
/**
* Creates a row {@link BigMatrix} using the data from the input
* array.
*
* @param rowData the input row data
* @return a 1 x rowData.length BigMatrix
* @throws IllegalArgumentException if rowData is empty
* @throws NullPointerException if rowDatais null
* @deprecated since 2.0 replaced by {@link #createRowFieldMatrix(FieldElement[])}
*/
@Deprecated
public static BigMatrix createRowBigMatrix(BigDecimal[] rowData) {
final int nCols = rowData.length;
final BigDecimal[][] data = new BigDecimal[1][nCols];
System.arraycopy(rowData, 0, data[0], 0, nCols);
return new BigMatrixImpl(data, false);
}
/**
* Creates a row {@link BigMatrix} using the data from the input
* array.
*
* @param rowData the input row data
* @return a 1 x rowData.length BigMatrix
* @throws IllegalArgumentException if rowData is empty
* @throws NullPointerException if rowDatais null
* @deprecated since 2.0 replaced by {@link #createRowFieldMatrix(FieldElement[])}
*/
@Deprecated
public static BigMatrix createRowBigMatrix(String[] rowData) {
final int nCols = rowData.length;
final BigDecimal[][] data = new BigDecimal[1][nCols];
for (int i = 0; i < nCols; ++i) {
data[0][i] = new BigDecimal(rowData[i]);
}
return new BigMatrixImpl(data, false);
}
/**
* Creates a column {@link RealMatrix} using the data from the input
* array.
*
* @param columnData the input column data
* @return a columnData x 1 RealMatrix
* @throws IllegalArgumentException if columnData is empty
* @throws NullPointerException if columnDatais null
*/
public static RealMatrix createColumnRealMatrix(double[] columnData) {
final int nRows = columnData.length;
final RealMatrix m = createRealMatrix(nRows, 1);
for (int i = 0; i < nRows; ++i) {
m.setEntry(i, 0, columnData[i]);
}
return m;
}
/**
* Creates a column {@link FieldMatrix} using the data from the input
* array.
*
* @param the type of the field elements
* @param columnData the input column data
* @return a columnData x 1 FieldMatrix
* @throws IllegalArgumentException if columnData is empty
* @throws NullPointerException if columnDatais null
*/
public static > FieldMatrix
createColumnFieldMatrix(final T[] columnData) {
final int nRows = columnData.length;
if (nRows == 0) {
throw MathRuntimeException.createIllegalArgumentException(LocalizedFormats.AT_LEAST_ONE_ROW);
}
final FieldMatrix m = createFieldMatrix(columnData[0].getField(), nRows, 1);
for (int i = 0; i < nRows; ++i) {
m.setEntry(i, 0, columnData[i]);
}
return m;
}
/**
* Creates a column {@link BigMatrix} using the data from the input
* array.
*
* @param columnData the input column data
* @return a columnData x 1 BigMatrix
* @throws IllegalArgumentException if columnData is empty
* @throws NullPointerException if columnDatais null
* @deprecated since 2.0 replaced by {@link #createColumnFieldMatrix(FieldElement[])}
*/
@Deprecated
public static BigMatrix createColumnBigMatrix(double[] columnData) {
final int nRows = columnData.length;
final BigDecimal[][] data = new BigDecimal[nRows][1];
for (int row = 0; row < nRows; row++) {
data[row][0] = new BigDecimal(columnData[row]);
}
return new BigMatrixImpl(data, false);
}
/**
* Creates a column {@link BigMatrix} using the data from the input
* array.
*
* @param columnData the input column data
* @return a columnData x 1 BigMatrix
* @throws IllegalArgumentException if columnData is empty
* @throws NullPointerException if columnDatais null
* @deprecated since 2.0 replaced by {@link #createColumnFieldMatrix(FieldElement[])}
*/
@Deprecated
public static BigMatrix createColumnBigMatrix(BigDecimal[] columnData) {
final int nRows = columnData.length;
final BigDecimal[][] data = new BigDecimal[nRows][1];
for (int row = 0; row < nRows; row++) {
data[row][0] = columnData[row];
}
return new BigMatrixImpl(data, false);
}
/**
* Creates a column {@link BigMatrix} using the data from the input
* array.
*
* @param columnData the input column data
* @return a columnData x 1 BigMatrix
* @throws IllegalArgumentException if columnData is empty
* @throws NullPointerException if columnDatais null
* @deprecated since 2.0 replaced by {@link #createColumnFieldMatrix(FieldElement[])}
*/
@Deprecated
public static BigMatrix createColumnBigMatrix(String[] columnData) {
int nRows = columnData.length;
final BigDecimal[][] data = new BigDecimal[nRows][1];
for (int row = 0; row < nRows; row++) {
data[row][0] = new BigDecimal(columnData[row]);
}
return new BigMatrixImpl(data, false);
}
/**
* Check if a row index is valid.
* @param m matrix containing the submatrix
* @param row row index to check
* @exception MatrixIndexException if index is not valid
*/
public static void checkRowIndex(final AnyMatrix m, final int row) {
if (row < 0 || row >= m.getRowDimension()) {
throw new MatrixIndexException(LocalizedFormats.ROW_INDEX_OUT_OF_RANGE,
row, 0, m.getRowDimension() - 1);
}
}
/**
* Check if a column index is valid.
* @param m matrix containing the submatrix
* @param column column index to check
* @exception MatrixIndexException if index is not valid
*/
public static void checkColumnIndex(final AnyMatrix m, final int column)
throws MatrixIndexException {
if (column < 0 || column >= m.getColumnDimension()) {
throw new MatrixIndexException(LocalizedFormats.COLUMN_INDEX_OUT_OF_RANGE,
column, 0, m.getColumnDimension() - 1);
}
}
/**
* Check if submatrix ranges indices are valid.
* Rows and columns are indicated counting from 0 to n-1.
*
* @param m matrix containing the submatrix
* @param startRow Initial row index
* @param endRow Final row index
* @param startColumn Initial column index
* @param endColumn Final column index
* @exception MatrixIndexException if the indices are not valid
*/
public static void checkSubMatrixIndex(final AnyMatrix m,
final int startRow, final int endRow,
final int startColumn, final int endColumn) {
checkRowIndex(m, startRow);
checkRowIndex(m, endRow);
if (startRow > endRow) {
throw new MatrixIndexException(LocalizedFormats.INITIAL_ROW_AFTER_FINAL_ROW,
startRow, endRow);
}
checkColumnIndex(m, startColumn);
checkColumnIndex(m, endColumn);
if (startColumn > endColumn) {
throw new MatrixIndexException(LocalizedFormats.INITIAL_COLUMN_AFTER_FINAL_COLUMN,
startColumn, endColumn);
}
}
/**
* Check if submatrix ranges indices are valid.
* Rows and columns are indicated counting from 0 to n-1.
*
* @param m matrix containing the submatrix
* @param selectedRows Array of row indices.
* @param selectedColumns Array of column indices.
* @exception MatrixIndexException if row or column selections are not valid
*/
public static void checkSubMatrixIndex(final AnyMatrix m,
final int[] selectedRows, final int[] selectedColumns)
throws MatrixIndexException {
if (selectedRows.length * selectedColumns.length == 0) {
if (selectedRows.length == 0) {
throw new MatrixIndexException(LocalizedFormats.EMPTY_SELECTED_ROW_INDEX_ARRAY);
}
throw new MatrixIndexException(LocalizedFormats.EMPTY_SELECTED_COLUMN_INDEX_ARRAY);
}
for (final int row : selectedRows) {
checkRowIndex(m, row);
}
for (final int column : selectedColumns) {
checkColumnIndex(m, column);
}
}
/**
* Check if matrices are addition compatible
* @param left left hand side matrix
* @param right right hand side matrix
* @exception IllegalArgumentException if matrices are not addition compatible
*/
public static void checkAdditionCompatible(final AnyMatrix left, final AnyMatrix right)
throws IllegalArgumentException {
if ((left.getRowDimension() != right.getRowDimension()) ||
(left.getColumnDimension() != right.getColumnDimension())) {
throw MathRuntimeException.createIllegalArgumentException(
LocalizedFormats.NOT_ADDITION_COMPATIBLE_MATRICES,
left.getRowDimension(), left.getColumnDimension(),
right.getRowDimension(), right.getColumnDimension());
}
}
/**
* Check if matrices are subtraction compatible
* @param left left hand side matrix
* @param right right hand side matrix
* @exception IllegalArgumentException if matrices are not subtraction compatible
*/
public static void checkSubtractionCompatible(final AnyMatrix left, final AnyMatrix right)
throws IllegalArgumentException {
if ((left.getRowDimension() != right.getRowDimension()) ||
(left.getColumnDimension() != right.getColumnDimension())) {
throw MathRuntimeException.createIllegalArgumentException(
LocalizedFormats.NOT_SUBTRACTION_COMPATIBLE_MATRICES,
left.getRowDimension(), left.getColumnDimension(),
right.getRowDimension(), right.getColumnDimension());
}
}
/**
* Check if matrices are multiplication compatible
* @param left left hand side matrix
* @param right right hand side matrix
* @exception IllegalArgumentException if matrices are not multiplication compatible
*/
public static void checkMultiplicationCompatible(final AnyMatrix left, final AnyMatrix right)
throws IllegalArgumentException {
if (left.getColumnDimension() != right.getRowDimension()) {
throw MathRuntimeException.createIllegalArgumentException(
LocalizedFormats.NOT_MULTIPLICATION_COMPATIBLE_MATRICES,
left.getRowDimension(), left.getColumnDimension(),
right.getRowDimension(), right.getColumnDimension());
}
}
/**
* Convert a {@link FieldMatrix}/{@link Fraction} matrix to a {@link RealMatrix}.
* @param m matrix to convert
* @return converted matrix
*/
public static Array2DRowRealMatrix fractionMatrixToRealMatrix(final FieldMatrix m) {
final FractionMatrixConverter converter = new FractionMatrixConverter();
m.walkInOptimizedOrder(converter);
return converter.getConvertedMatrix();
}
/** Converter for {@link FieldMatrix}/{@link Fraction}. */
private static class FractionMatrixConverter extends DefaultFieldMatrixPreservingVisitor {
/** Converted array. */
private double[][] data;
/** Simple constructor. */
public FractionMatrixConverter() {
super(Fraction.ZERO);
}
/** {@inheritDoc} */
@Override
public void start(int rows, int columns,
int startRow, int endRow, int startColumn, int endColumn) {
data = new double[rows][columns];
}
/** {@inheritDoc} */
@Override
public void visit(int row, int column, Fraction value) {
data[row][column] = value.doubleValue();
}
/** Get the converted matrix.
* @return converted matrix
*/
Array2DRowRealMatrix getConvertedMatrix() {
return new Array2DRowRealMatrix(data, false);
}
}
/**
* Convert a {@link FieldMatrix}/{@link BigFraction} matrix to a {@link RealMatrix}.
* @param m matrix to convert
* @return converted matrix
*/
public static Array2DRowRealMatrix bigFractionMatrixToRealMatrix(final FieldMatrix m) {
final BigFractionMatrixConverter converter = new BigFractionMatrixConverter();
m.walkInOptimizedOrder(converter);
return converter.getConvertedMatrix();
}
/** Converter for {@link FieldMatrix}/{@link BigFraction}. */
private static class BigFractionMatrixConverter extends DefaultFieldMatrixPreservingVisitor {
/** Converted array. */
private double[][] data;
/** Simple constructor. */
public BigFractionMatrixConverter() {
super(BigFraction.ZERO);
}
/** {@inheritDoc} */
@Override
public void start(int rows, int columns,
int startRow, int endRow, int startColumn, int endColumn) {
data = new double[rows][columns];
}
/** {@inheritDoc} */
@Override
public void visit(int row, int column, BigFraction value) {
data[row][column] = value.doubleValue();
}
/** Get the converted matrix.
* @return converted matrix
*/
Array2DRowRealMatrix getConvertedMatrix() {
return new Array2DRowRealMatrix(data, false);
}
}
/** Serialize a {@link RealVector}.
*
* This method is intended to be called from within a private
* writeObject method (after a call to
* oos.defaultWriteObject()) in a class that has a
* {@link RealVector} field, which should be declared transient.
* This way, the default handling does not serialize the vector (the {@link
* RealVector} interface is not serializable by default) but this method does
* serialize it specifically.
*
*
* The following example shows how a simple class with a name and a real vector
* should be written:
*
* public class NamedVector implements Serializable {
*
* private final String name;
* private final transient RealVector coefficients;
*
* // omitted constructors, getters ...
*
* private void writeObject(ObjectOutputStream oos) throws IOException {
* oos.defaultWriteObject(); // takes care of name field
* MatrixUtils.serializeRealVector(coefficients, oos);
* }
*
* private void readObject(ObjectInputStream ois) throws ClassNotFoundException, IOException {
* ois.defaultReadObject(); // takes care of name field
* MatrixUtils.deserializeRealVector(this, "coefficients", ois);
* }
*
* }
*
*
*
* @param vector real vector to serialize
* @param oos stream where the real vector should be written
* @exception IOException if object cannot be written to stream
* @see #deserializeRealVector(Object, String, ObjectInputStream)
*/
public static void serializeRealVector(final RealVector vector,
final ObjectOutputStream oos)
throws IOException {
final int n = vector.getDimension();
oos.writeInt(n);
for (int i = 0; i < n; ++i) {
oos.writeDouble(vector.getEntry(i));
}
}
/** Deserialize a {@link RealVector} field in a class.
*
* This method is intended to be called from within a private
* readObject method (after a call to
* ois.defaultReadObject()) in a class that has a
* {@link RealVector} field, which should be declared transient.
* This way, the default handling does not deserialize the vector (the {@link
* RealVector} interface is not serializable by default) but this method does
* deserialize it specifically.
*
* @param instance instance in which the field must be set up
* @param fieldName name of the field within the class (may be private and final)
* @param ois stream from which the real vector should be read
* @exception ClassNotFoundException if a class in the stream cannot be found
* @exception IOException if object cannot be read from the stream
* @see #serializeRealVector(RealVector, ObjectOutputStream)
*/
public static void deserializeRealVector(final Object instance,
final String fieldName,
final ObjectInputStream ois)
throws ClassNotFoundException, IOException {
try {
// read the vector data
final int n = ois.readInt();
final double[] data = new double[n];
for (int i = 0; i < n; ++i) {
data[i] = ois.readDouble();
}
// create the instance
final RealVector vector = new ArrayRealVector(data, false);
// set up the field
final java.lang.reflect.Field f =
instance.getClass().getDeclaredField(fieldName);
f.setAccessible(true);
f.set(instance, vector);
} catch (NoSuchFieldException nsfe) {
IOException ioe = new IOException();
ioe.initCause(nsfe);
throw ioe;
} catch (IllegalAccessException iae) {
IOException ioe = new IOException();
ioe.initCause(iae);
throw ioe;
}
}
/** Serialize a {@link RealMatrix}.
*
* This method is intended to be called from within a private
* writeObject method (after a call to
* oos.defaultWriteObject()) in a class that has a
* {@link RealMatrix} field, which should be declared transient.
* This way, the default handling does not serialize the matrix (the {@link
* RealMatrix} interface is not serializable by default) but this method does
* serialize it specifically.
*
*
* The following example shows how a simple class with a name and a real matrix
* should be written:
*
* public class NamedMatrix implements Serializable {
*
* private final String name;
* private final transient RealMatrix coefficients;
*
* // omitted constructors, getters ...
*
* private void writeObject(ObjectOutputStream oos) throws IOException {
* oos.defaultWriteObject(); // takes care of name field
* MatrixUtils.serializeRealMatrix(coefficients, oos);
* }
*
* private void readObject(ObjectInputStream ois) throws ClassNotFoundException, IOException {
* ois.defaultReadObject(); // takes care of name field
* MatrixUtils.deserializeRealMatrix(this, "coefficients", ois);
* }
*
* }
*
*
*
* @param matrix real matrix to serialize
* @param oos stream where the real matrix should be written
* @exception IOException if object cannot be written to stream
* @see #deserializeRealMatrix(Object, String, ObjectInputStream)
*/
public static void serializeRealMatrix(final RealMatrix matrix,
final ObjectOutputStream oos)
throws IOException {
final int n = matrix.getRowDimension();
final int m = matrix.getColumnDimension();
oos.writeInt(n);
oos.writeInt(m);
for (int i = 0; i < n; ++i) {
for (int j = 0; j < m; ++j) {
oos.writeDouble(matrix.getEntry(i, j));
}
}
}
/** Deserialize a {@link RealMatrix} field in a class.
*
* This method is intended to be called from within a private
* readObject method (after a call to
* ois.defaultReadObject()) in a class that has a
* {@link RealMatrix} field, which should be declared transient.
* This way, the default handling does not deserialize the matrix (the {@link
* RealMatrix} interface is not serializable by default) but this method does
* deserialize it specifically.
*
* @param instance instance in which the field must be set up
* @param fieldName name of the field within the class (may be private and final)
* @param ois stream from which the real matrix should be read
* @exception ClassNotFoundException if a class in the stream cannot be found
* @exception IOException if object cannot be read from the stream
* @see #serializeRealMatrix(RealMatrix, ObjectOutputStream)
*/
public static void deserializeRealMatrix(final Object instance,
final String fieldName,
final ObjectInputStream ois)
throws ClassNotFoundException, IOException {
try {
// read the matrix data
final int n = ois.readInt();
final int m = ois.readInt();
final double[][] data = new double[n][m];
for (int i = 0; i < n; ++i) {
final double[] dataI = data[i];
for (int j = 0; j < m; ++j) {
dataI[j] = ois.readDouble();
}
}
// create the instance
final RealMatrix matrix = new Array2DRowRealMatrix(data, false);
// set up the field
final java.lang.reflect.Field f =
instance.getClass().getDeclaredField(fieldName);
f.setAccessible(true);
f.set(instance, matrix);
} catch (NoSuchFieldException nsfe) {
IOException ioe = new IOException();
ioe.initCause(nsfe);
throw ioe;
} catch (IllegalAccessException iae) {
IOException ioe = new IOException();
ioe.initCause(iae);
throw ioe;
}
}
}