jsat.linear

Class RandomMatrix

java.lang.Object

jsat.linear.Matrix

jsat.linear.GenericMatrix

jsat.linear.RandomMatrix

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable

public abstract class RandomMatrix
extends GenericMatrix

Stores a Matrix full of random values in constant O(1) space by re-computing all matrix values on the fly as need. This allows memory reduction and use when it is necessary to use the matrix with a large sparse data set, where some matrix values may never even be used - or used very infrequently.

This method is most useful when:

• A random matrix can not be fit into main memory
• An in memory matrix with the model being trained would result in swapping , in which case the slower Random Matrix would be faster since it can avoid swapping
• A very large matrix must be synchronized across many threads or machines. The Random Matrix takes O(1) space and is thread safe
• Initializing a random dense matrix
• The accesses of the matrix is sparse enough that not all matrix values will get used, or used very infrequently

Because the values of the random matrix are computed on the fly, the Random Matrix can not be altered. If attempted, an exception will be thrown.

Because a Random Matric can not be altered, it can not fulfill the contract of getMatrixOfSameType(int, int). For this reason, it will return a DenseMatrix so that use cases of the given method do not break, and can return new - altered - matrices.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
RandomMatrix(int rows, int cols) Creates a new random matrix object
RandomMatrix(int rows, int cols, long seedMult) Creates a new random matrix object
RandomMatrix(RandomMatrix toCopy) Copy constructor

Method Summary

Modifier and Type	Method and Description
boolean	canBeMutated() Indicates whether or not this matrix can be mutated.
void	changeSize(int newRows, int newCols) This method alters the size of a matrix, either adding or subtracting rows from the internal structure of the matrix.
int	cols() Returns the number of columns stored in this matrix
double	get(int i, int j) Returns the value stored at at the matrix position Ai,j
boolean	isSparce() Returns true if the matrix is sparse, false otherwise
int	rows() Returns the number of rows stored in this matrix
void	set(int i, int j, double value) Sets the value stored at at the matrix position Ai,j

Methods inherited from class jsat.linear.GenericMatrix

clone, lup, lup, multiply, multiply, multiply, multiplyTranspose, multiplyTranspose, mutableAdd, mutableAdd, mutableAdd, mutableAdd, mutableMultiply, mutableMultiply, mutableTranspose, qr, qr, swapRows, transpose, transposeMultiply, transposeMultiply, transposeMultiply, zeroOut

Methods inherited from class jsat.linear.Matrix

add, add, add, add, canMultiply, copyTo, diag, diagMult, diagMult, equals, equals, eye, getColumn, getColumnView, getRow, getRowView, increment, isSquare, isSymmetric, isSymmetric, multiply, multiply, multiply, multiply, multiply, multiplyTranspose, multiplyTranspose, mutableAdd, mutableAdd, mutableSubtract, mutableSubtract, mutableSubtract, mutableSubtract, mutableSubtract, mutableSubtract, nnz, OuterProductUpdate, OuterProductUpdate, pascal, random, sameDimensions, subtract, subtract, subtract, subtract, toString, transpose, transposeMultiply, transposeMultiply, transposeMultiply, updateRow

Methods inherited from class java.lang.Object

getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

RandomMatrix

public RandomMatrix(int rows,
                    int cols)

Creates a new random matrix object

Parameters:

rows - the number of rows for the random matrix

cols - the number of columns for the random matrix

RandomMatrix

public RandomMatrix(int rows,
                    int cols,
                    long seedMult)

Creates a new random matrix object

Parameters:

rows - the number of rows for the random matrix

cols - the number of columns for the random matrix

seedMult - a value to multiply with the seed used for each individual index. It should be a large value

RandomMatrix

public RandomMatrix(RandomMatrix toCopy)

Copy constructor

Parameters:

toCopy - the object to copy

Method Detail

get

public double get(int i,
                  int j)

Description copied from class: Matrix

Returns the value stored at at the matrix position A_i,j

Specified by:

get in class Matrix

Parameters:

i - the row, starting from 0

j - the column, starting from 0

Returns:

the value at A_i,j

set

public void set(int i,
                int j,
                double value)

Description copied from class: Matrix

Sets the value stored at at the matrix position A_i,j

Specified by:

set in class Matrix

Parameters:

i - the row, starting from 0

j - the column, starting from 0

value - the value to place at A_i,j

rows

public int rows()

Description copied from class: Matrix

Returns the number of rows stored in this matrix

Specified by:

rows in class Matrix

Returns:

the number of rows stored in this matrix

cols

public int cols()

Description copied from class: Matrix

Returns the number of columns stored in this matrix

Specified by:

cols in class Matrix

Returns:

the number of columns stored in this matrix

isSparce

public boolean isSparce()

Description copied from class: Matrix

Returns true if the matrix is sparse, false otherwise

Specified by:

isSparce in class Matrix

Returns:

true if the matrix is sparse, false otherwise

canBeMutated

public boolean canBeMutated()

Description copied from class: Matrix

Indicates whether or not this matrix can be mutated. If false, any method that contains "mutate" will not work.

By default, this returns true

Overrides:

canBeMutated in class Matrix

Returns:

true if the matrix supports being altered, false other wise.

changeSize

public void changeSize(int newRows,
                       int newCols)

Description copied from class: Matrix

This method alters the size of a matrix, either adding or subtracting rows from the internal structure of the matrix. Every resize call may cause a new allocation internally, and should not be called for excessive changing of a matrix. All added rows/ columns will have values of zero. If a row / column is removed, it is always the bottom/right most row / column removed. Values of the removed rows / columns will be lost.

Specified by:

changeSize in class Matrix

Parameters:

newRows - the new number of rows, must be positive

newCols - the new number of columns, must be positive.