edu.ucla.sspace.matrix

Class SparseOnDiskMatrix

java.lang.Object

edu.ucla.sspace.matrix.OnDiskMatrix

edu.ucla.sspace.matrix.SparseOnDiskMatrix

All Implemented Interfaces:

Matrix, SparseMatrix

public class SparseOnDiskMatrix
extends OnDiskMatrix
implements SparseMatrix

A SparseMatrix implementation that uses a binary file to read and write. The matrix is still stored in a dense 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. However calls to getRowVector and getColumnVector will return SparseVector instances. This class is intended for large matrices that need to be on disk due to their dimensions, but whose data is mostly sparse

The DoubleVector representations returned reflect a snapshot of the state of the matrix at the time of access. Subsequent updates to the matrix will not be reflected in these vectors, nor will changes to the vector be propagated to the matrix.

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

Method Summary

Methods

Modifier and Type	Method and Description
SparseDoubleVector	getColumnVector(int column) Returns the column as a vector.
SparseDoubleVector	getRowVector(int row) Returns a DoubleVector for an entire row.
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.

Methods inherited from class edu.ucla.sspace.matrix.OnDiskMatrix

columns, finalize, get, getColumn, getRow, rows, toDenseArray

Methods inherited from class java.lang.Object

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

Methods inherited from interface edu.ucla.sspace.matrix.Matrix

columns, get, getColumn, getRow, rows, toDenseArray

Constructor Detail

SparseOnDiskMatrix

public SparseOnDiskMatrix(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

getColumnVector

public SparseDoubleVector 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

Specified by:

getColumnVector in interface SparseMatrix

Overrides:

getColumnVector in class OnDiskMatrix

Parameters:

column - The column to return a DoubleVector for.

Returns:

A DoubleVector representing the column at column.

getRowVector

public SparseDoubleVector 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

Specified by:

getRowVector in interface SparseMatrix

Overrides:

getRowVector in class OnDiskMatrix

Parameters:

row - the index of the row to return.

Returns:

A DoubleVector representing the row at row.

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

Overrides:

set in class OnDiskMatrix

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

Overrides:

setColumn in class OnDiskMatrix

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

Overrides:

setColumn in class OnDiskMatrix

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

Overrides:

setRow in class OnDiskMatrix

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

Overrides:

setRow in class OnDiskMatrix

Parameters:

row - The row to update.

values - The values to update into row.