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Class weka.core.Matrix

java.lang.Object
    |
    +----weka.core.Matrix

public class Matrix

extends java.lang.Object

implements java.lang.Cloneable, java.io.Serializable

Version:

$Revision: 1.17 $

Author:

Gabi Schmidberger (gabi@cs.waikato.ac.nz)

Author:

Yong Wang (yongwang@cs.waikato.ac.nz)

Author:

Eibe Frank (eibe@cs.waikato.ac.nz)

Author:

Len Trigg (eibe@cs.waikato.ac.nz)

Matrix(double[][])

Constructs a matrix using a given array.

Matrix(int, int)

Constructs a matrix and initializes it with default values.

Matrix(Reader)

Reads a matrix from a reader.

add(Matrix)

Returns the sum of this matrix with another.

addElement(int, int, double)

Add a value to an element.

clone()

Creates and returns a clone of this object.

eigenvalueDecomposition(double[][], double[])

Performs Eigenvalue Decomposition using Householder QR Factorization This function is adapted from the CERN Jet Java libraries, for it the following copyright applies (see also, text on top of file) Copyright (C) 1999 CERN - European Organization for Nuclear Research.

getColumn(int)

Gets a column of the matrix and returns it as a double array.

getElement(int, int)

Returns the value of a cell in the matrix.

getL()

Returns the L part of the matrix.

getRow(int)

Gets a row of the matrix and returns it as double array.

getU()

Returns the U part of the matrix.

isSymmetric()

Returns true if the matrix is symmetric.

LUDecomposition()

Performs a LUDecomposition on the matrix.

main(String[])

Main method for testing this class.

multiply(Matrix)

Returns the multiplication of two matrices

numColumns()

Returns the number of columns in the matrix.

numRows()

Returns the number of rows in the matrix.

regression(Matrix, double)

Performs a (ridged) linear regression.

regression(Matrix, double[], double)

Performs a weighted (ridged) linear regression.

setColumn(int, double[])

Sets a column of the matrix to the given column.

setElement(int, int, double)

Sets an element of the matrix to the given value.

setRow(int, double[])

Sets a row of the matrix to the given row.

solve(double[])

Solve A*X = B using backward substitution.

testEigen(Matrix, double[], boolean)

Test eigenvectors and eigenvalues.

toString()

Converts a matrix to a string

transpose()

Returns the transpose of a matrix.

write(Writer)

Writes out a matrix.

public Matrix(int nr,
              int nc)

          Constructs a matrix and initializes it with default values.

Parameters:

nr - the number of rows

nc - the number of columns

public Matrix(double array[][]) throws java.lang.Exception

          Constructs a matrix using a given array.

Parameters:

array - the values of the matrix

public Matrix(java.io.Reader r) throws java.lang.Exception

          Reads a matrix from a reader. The first line in the file should contain the number of rows and columns. Subsequent lines contain elements of the matrix.

Parameters:

r - the reader containing the matrix

Throws:

java.lang.Exception - if an error occurs

public java.lang.Object clone() throws java.lang.CloneNotSupportedException

          Creates and returns a clone of this object.

Returns:

a clone of this instance.

Throws:

java.lang.CloneNotSupportedException - if an error occurs

public void write(java.io.Writer w) throws java.lang.Exception

          Writes out a matrix.

Parameters:

w - the output Writer

Throws:

java.lang.Exception - if an error occurs

public final double getElement(int rowIndex,
                               int columnIndex)

          Returns the value of a cell in the matrix.

Parameters:

rowIndex - the row's index

columnIndex - the column's index

Returns:

the value of the cell of the matrix

public final void addElement(int rowIndex,
                             int columnIndex,
                             double value)

          Add a value to an element.

Parameters:

rowIndex - the row's index.

columnIndex - the column's index.

value - the value to add.

public final int numRows()

          Returns the number of rows in the matrix.

Returns:

the number of rows

public final int numColumns()

          Returns the number of columns in the matrix.

Returns:

the number of columns

public final void setElement(int rowIndex,
                             int columnIndex,
                             double value)

          Sets an element of the matrix to the given value.

Parameters:

rowIndex - the row's index

columnIndex - the column's index

value - the value

public final void setRow(int index,
                         double newRow[])

          Sets a row of the matrix to the given row. Performs a deep copy.

Parameters:

index - the row's index

newRow - an array of doubles

public double[] getRow(int index)

          Gets a row of the matrix and returns it as double array.

Parameters:

index - the row's index

Returns:

an array of doubles

public double[] getColumn(int index)

          Gets a column of the matrix and returns it as a double array.

Parameters:

index - the column's index

Returns:

an array of doubles

public final void setColumn(int index,
                            double newColumn[])

          Sets a column of the matrix to the given column. Performs a deep copy.

Parameters:

index - the column's index

newColumn - an array of doubles

public java.lang.String toString()

          Converts a matrix to a string

Returns:

the converted string

Overrides:

toString in class java.lang.Object

public final Matrix add(Matrix other)

          Returns the sum of this matrix with another.

Returns:

a matrix containing the sum.

public final Matrix transpose()

          Returns the transpose of a matrix.

Returns:

the transposition of this instance.

public boolean isSymmetric()

          Returns true if the matrix is symmetric.

Returns:

boolean true if matrix is symmetric.

public final Matrix multiply(Matrix b)

          Returns the multiplication of two matrices

Parameters:

b - the multiplication matrix

Returns:

the product matrix

public final double[] regression(Matrix y,
                                 double ridge)

          Performs a (ridged) linear regression.

Parameters:

y - the dependent variable vector

ridge - the ridge parameter

Returns:

the coefficients

Throws:

java.lang.IllegalArgumentException - if not successful

public final double[] regression(Matrix y,
                                 double w[],
                                 double ridge)

          Performs a weighted (ridged) linear regression.

Parameters:

y - the dependent variable vector

w - the array of data point weights

ridge - the ridge parameter

Returns:

the coefficients

Throws:

java.lang.IllegalArgumentException - if the wrong number of weights were provided.

public Matrix getL() throws java.lang.Exception

          Returns the L part of the matrix. This does only make sense after LU decomposition.

Returns:

matrix with the L part of the matrix;

public Matrix getU() throws java.lang.Exception

          Returns the U part of the matrix. This does only make sense after LU decomposition.

Returns:

matrix with the U part of a matrix;

public int[] LUDecomposition() throws java.lang.Exception

          Performs a LUDecomposition on the matrix. It changes the matrix into its LU decomposition using the Crout algorithm

Returns:

the indices of the row permutation

Throws:

java.lang.Exception - if the matrix is singular

public void solve(double bb[]) throws java.lang.Exception

          Solve A*X = B using backward substitution. A is current object (this) B parameter bb X returned in parameter bb

Parameters:

bb - first vektor B in above equation then X in same equation.

Throws:

matrix - is singulaer

public void eigenvalueDecomposition(double V[][],
                                    double d[]) throws java.lang.Exception

          Performs Eigenvalue Decomposition using Householder QR Factorization This function is adapted from the CERN Jet Java libraries, for it the following copyright applies (see also, text on top of file) Copyright (C) 1999 CERN - European Organization for Nuclear Research. Matrix must be symmetrical. Eigenvectors are return in parameter V, as columns of the 2D array. Eigenvalues are returned in parameter d.

Parameters:

V - double array in which the eigenvectors are returned

d - array in which the eigenvalues are returned

Throws:

if - matrix is not symmetric

public boolean testEigen(Matrix V,
                         double d[],
                         boolean verbose) throws java.lang.Exception

          Test eigenvectors and eigenvalues. function is used for debugging

Parameters:

V - matrix with eigenvectors of A

d - array with eigenvalues of A

Throws:

if - new matrix cannot be made

public static void main(java.lang.String ops[])

          Main method for testing this class.

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