edu.ucla.sspace.matrix

Class SparseHashMatrix

java.lang.Object

edu.ucla.sspace.matrix.AbstractMatrix

edu.ucla.sspace.matrix.SparseHashMatrix

All Implemented Interfaces:

Matrix, SparseMatrix

public class SparseHashMatrix
extends AbstractMatrix
implements SparseMatrix

A SparseMatrix backed by vectors that provide amortized O(1) access to their elements. Each row is implemented using a hashing-based vector. This class provides an alternate implementation to YaleSparseMatrix; this class potentially uses more memory than YaleSparseMatrix, but provides O(1) access instead of O(log(n)). 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
SparseHashMatrix(int rows, int columns) 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.
SparseDoubleVector	getColumnVector(int column) Returns the column as a vector.
SparseDoubleVector	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) Throws an UnsupportedOperationException if called (matrix is unmodifiable).

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

equals, get, getColumn, getRow, hashCode, setColumn, setColumn, setRow, setRow, toDenseArray

Methods inherited from class java.lang.Object

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

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

get, getColumn, getRow, setColumn, setColumn, setRow, setRow, toDenseArray

Constructor Detail

SparseHashMatrix

public SparseHashMatrix(int rows,
                int columns)

Constructs a sparse matrix with the specified dimensions.

Method Detail

columns

public int columns()

Returns the number of columns in this Matrix.

Specified by:

columns in interface Matrix

Specified by:

columns in class AbstractMatrix

Returns:

The number of columns in this Matrix.

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 AbstractMatrix

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

Specified by:

getRowVector in class AbstractMatrix

Parameters:

row - the index of the row to return.

Returns:

A DoubleVector representing the row at row.

rows

public int rows()

Returns the number of rows in this Matrix.

Specified by:

rows in interface Matrix

Specified by:

rows in class AbstractMatrix

Returns:

The number of columns in this Matrix.

set

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

Throws an UnsupportedOperationException if called (matrix is unmodifiable).

Specified by:

set in interface Matrix

Overrides:

set in class AbstractMatrix

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.