edu.ucla.sspace.matrix

Class ArrayMatrix

java.lang.Object

edu.ucla.sspace.matrix.ArrayMatrix

All Implemented Interfaces:

Matrix

public class ArrayMatrix
extends Object
implements Matrix

A Matrix backed by an array. The matrix is represented in row-striped format, so row-based access will have better performance.

The DoubleVector views of this matrix are back by data in the array so changes to the vectors will be reflected in the matrix and vice versa.

Author:

David Jurgens

Nested Class Summary

Nested classes/interfaces inherited from interface edu.ucla.sspace.matrix.Matrix

Matrix.Type

Constructor Summary

Constructors

Constructor and Description
ArrayMatrix(double[][] matrix2d) Create a ArrayMatrix from a two dimensional array.
ArrayMatrix(int rows, int cols) Create a ArrayMatrix of size rows by cols.
ArrayMatrix(int rows, int cols, double[] matrix1D) Create a new ArrayMatrix which is of dimensions rows by cols, and takes ownership of matrix1d as the values of this ArrayMatrix.

Method Summary

Methods

Modifier and Type	Method and Description
int	columns() Returns the number of columns in this Matrix.
double	get(int row, int col) Returns the value of the Matrix at the provided row and column.
double[]	getColumn(int column) Returns the entire column.
DoubleVector	getColumnVector(int column) Returns the column as a vector.
double[]	getRow(int row) Returns the entire row.
DoubleVector	getRowVector(int row) Returns a DoubleVector for an entire row.
int	rows() Returns the number of rows in this Matrix.
void	set(int row, int col, double val) Sets the location at the row and column to the provided value.
void	setColumn(int column, double[] values) Sets the values for the column of this Matrix using the provided array.
void	setColumn(int column, DoubleVector values) Sets the values for the column of this Matrix using the provided DoubleVector.
void	setRow(int row, double[] columns) Sets the values for the row of this Matrix using the provided array.
void	setRow(int row, DoubleVector values) Sets the values for the row of this Matrix using the provided DoubleVector.
double[][]	toDenseArray() Converts the Matrix to a two dimensional array.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ArrayMatrix

public ArrayMatrix(int rows,
           int cols)

Create a ArrayMatrix of size rows by cols.

Parameters:

rows - The number of rows this ArrayMatrix will represent.

cols - The number of columns this ArrayMatrix will represent.

ArrayMatrix

public ArrayMatrix(double[][] matrix2d)

Create a ArrayMatrix from a two dimensional array.

Parameters:

matrix2d - The two dimensional array this ArrayMatrix will represent.

Throws:

IllegalArgumentExceptiona - if matrix2d is invalid.

ArrayMatrix

public ArrayMatrix(int rows,
           int cols,
           double[] matrix1D)

Create a new ArrayMatrix which is of dimensions rows by cols, and takes ownership of matrix1d as the values of this ArrayMatrix. Note that matrix1D should be of length rows * cols.

Parameters:

rows - The number of rows this ArrayMatrix will represent.

cols - The number of columns this ArrayMatrix will represent.

matrix1D - A 1 dimensional representation of the vaues this ArrayMatrix will have.

Throws:

IllegalArgumentException - if either rows or cols is negative, or matrix1d is invalid.

Method Detail

get

public double get(int row,
         int col)

Returns the value of the Matrix at the provided row and column.

Specified by:

get in interface Matrix

Parameters:

row - The row values of the cell to return.

col - The column value of the cell to return.

Returns:

The value at the cell specified by row and col.

getColumn

public double[] getColumn(int column)

Returns the entire column.

Specified by:

getColumn in interface Matrix

Parameters:

column - The column to return an array for.

Returns:

A double array representing the column at column.

getColumnVector

public DoubleVector getColumnVector(int column)

Returns the column as a vector. Whether updates to the vector are written through to the backing matrix is left open to the specific implementation. Implementations that maintain their data in a sparse format are encouraged to return a SparseVector instance.

Specified by:

getColumnVector in interface Matrix

Parameters:

column - The column to return a DoubleVector for.

Returns:

A DoubleVector representing the column at column.

getRow

public double[] getRow(int row)

Returns the entire row.

Specified by:

getRow in interface Matrix

Parameters:

row - The row to return an array for.

Returns:

A double array representing the row at row.

getRowVector

public DoubleVector getRowVector(int row)

Returns a DoubleVector for an entire row. Implementations should return an approriately typed DoubleVector. Whether updates to the vector are written through to the backing matrix is left open to the specific implementation. Implementations that maintain their data in a sparse format are encouraged to return a SparseVector instance.

Specified by:

getRowVector in interface Matrix

Parameters:

row - the index of the row to return.

Returns:

A DoubleVector representing the row at row.

columns

public int columns()

Returns the number of columns in this Matrix.

Specified by:

columns in interface Matrix

Returns:

The number of columns in this Matrix.

set

public void set(int row,
       int col,
       double val)

Sets the location at the row and column to the provided value.

Specified by:

set in interface Matrix

Parameters:

row - The row of the cell to update.

col - The column of the cell to update.

val - The new value of the specified cell.

setColumn

public void setColumn(int column,
             double[] values)

Sets the values for the column of this Matrix using the provided array. Note that the array itself is not made internal to the instance itself.

Specified by:

setColumn in interface Matrix

Parameters:

column - The column to update.

values - The values to update into column.

setColumn

public void setColumn(int column,
             DoubleVector values)

Sets the values for the column of this Matrix using the provided DoubleVector. Note that the DoubleVector itself is not made internal to the instance itself.

Specified by:

setColumn in interface Matrix

Parameters:

column - The column to update.

values - The values to update into column.

setRow

public void setRow(int row,
          double[] columns)

Sets the values for the row of this Matrix using the provided array. Note that the array itself is not made internal to the instance itself.

Specified by:

setRow in interface Matrix

Parameters:

row - The row to update.

columns - The values to update into row.

setRow

public void setRow(int row,
          DoubleVector values)

Sets the values for the row of this Matrix using the provided DoubleVector. Note that the DoubleVector itself is not made internal to the instance itself.

Specified by:

setRow in interface Matrix

Parameters:

row - The row to update.

values - The values to update into row.

toDenseArray

public double[][] toDenseArray()

Converts the Matrix to a two dimensional array. Note that for large matrices, this may exhaust all available memory.

Specified by:

toDenseArray in interface Matrix

Returns:

A double array version of this Matrix.

rows

public int rows()

Returns the number of rows in this Matrix.

Specified by:

rows in interface Matrix

Returns:

The number of columns in this Matrix.