edu.ucla.sspace.matrix

Class YaleSparseMatrix

java.lang.Object

edu.ucla.sspace.matrix.YaleSparseMatrix

All Implemented Interfaces:

Matrix, SparseMatrix

public class YaleSparseMatrix
extends Object
implements SparseMatrix

A sparse Matrix based on the Yale Sparse Matrix Format, as implemented in CompactSparseVector. Each row is allocated a pair of arrays which keeps the non-zero column values in column order. Lookups are O(log n) where n is the number of non-zero values for the largest row. The size of this matrix is fixed, and attempts to access rows or columns beyond the size will throw an IndexOutOfBoundsException.

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
YaleSparseMatrix(double[][] values) Constructs a sparse matrix using values from the given two dimension array.
YaleSparseMatrix(int rows, int cols) Constructs a sparse matrix with the specified dimensions.

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.
SparseDoubleVector	getColumnVector(int column) Returns the column as a sparse vector.
double[]	getRow(int row) Returns the entire row.
SparseDoubleVector	getRowVector(int row) Returns the row as a sparse vector.
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

YaleSparseMatrix

public YaleSparseMatrix(int rows,
                int cols)

Constructs a sparse matrix with the specified dimensions.

YaleSparseMatrix

public YaleSparseMatrix(double[][] values)

Constructs a sparse matrix using values from the given two dimension array. Only non-zero values will be stored.

Throws:

IllegalArgumentException - If either the number of rows is equal to 0, or the column lengths are jagged

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 SparseDoubleVector getColumnVector(int column)

Returns the column as a sparse vector. Whether updates to the vector are written through to the backing matrix is left open to the implementation.

Specified by:

getColumnVector in interface Matrix

Specified by:

getColumnVector in interface SparseMatrix

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 SparseDoubleVector getRowVector(int row)

Returns the row as a sparse vector. Whether updates to the vector are written through to the backing matrix is left open to the implementation.

Specified by:

getRowVector in interface Matrix

Specified by:

getRowVector in interface SparseMatrix

Parameters:

row - the index of row to return

Returns:

A SparseDoubleVector of the row's data

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.