edu.ucla.sspace.matrix

Class OnDiskMatrix

java.lang.Object

edu.ucla.sspace.matrix.OnDiskMatrix

All Implemented Interfaces:

Matrix

Direct Known Subclasses:

SparseOnDiskMatrix

public class OnDiskMatrix
extends Object
implements Matrix

A Matrix implementation that uses a binary file to read and write Returns a copy of the specified rowvalues of the matrix. The matrix is stored in row-column order on disk, so in-order column accesses to elments in a row will perform much better than sequential row accesses to the same column.

If a IOException is ever raised as a part of executing an the methods of an instance, the exception is rethrown as a IOError.

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
OnDiskMatrix(int rows, int cols) Create a matrix of the provided size using a temporary file.

Method Summary

Methods

Modifier and Type	Method and Description
int	columns() Returns the number of columns in this Matrix.
protected void	finalize() Upon finalize, deletes all of the backing files.
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[] vals) 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, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

OnDiskMatrix

public OnDiskMatrix(int rows,
            int cols)

Create a matrix of the provided size using a temporary file.

Throws:

IOError - if the backing file for this matrix cannot be created

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[] vals)

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.

vals - 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.

finalize

protected void finalize()

Upon finalize, deletes all of the backing files. This is most necessary when the JVM is long-running with many OnDiskMatrix instances that are not deleted until exit.

Overrides:

finalize in class Object