cern.colt.matrix
Class DoubleFactory2D

java.lang.Object
  cern.colt.PersistentObject
      cern.colt.matrix.DoubleFactory2D

All Implemented Interfaces:

Cloneable, Serializable

public class DoubleFactory2D

extends PersistentObject

Factory for convenient construction of 2-d matrices holding double cells. Also provides convenient methods to compose (concatenate) and decompose (split) matrices from/to constituent blocks.

If the factory is used frequently it might be useful to streamline the notation. For example by aliasing:

DoubleFactory2D F = DoubleFactory2D.dense;
F.make(4,4);
F.descending(10,20);
F.random(4,4);
...

Version:

1.0, 09/24/99

See Also:

Serialized Form

dense

public static final DoubleFactory2D dense

A factory producing dense matrices.

sparse

public static final DoubleFactory2D sparse

A factory producing sparse hash matrices.

rowCompressed

public static final DoubleFactory2D rowCompressed

A factory producing sparse row compressed matrices.

appendColumns

public DoubleMatrix2D appendColumns(DoubleMatrix2D A,
                                    DoubleMatrix2D B)

C = A||B; Constructs a new matrix which is the column-wise concatenation of two other matrices.

0 1 2
3 4 5
appendColumns
6 7
8 9
-->
0 1 2 6 7 
3 4 5 8 9

appendRows

public DoubleMatrix2D appendRows(DoubleMatrix2D A,
                                 DoubleMatrix2D B)

C = A||B; Constructs a new matrix which is the row-wise concatenation of two other matrices.

0 1 
2 3 
4 5
appendRows
6 7
8 9
-->
0 1 
2 3 
4 5
6 7
8 9

ascending

public DoubleMatrix2D ascending(int rows,
                                int columns)

Constructs a matrix with cells having ascending values. For debugging purposes. Example:

0 1 2 
3 4 5

compose

public DoubleMatrix2D compose(DoubleMatrix2D[][] parts)

Constructs a block matrix made from the given parts. The inverse to method decompose(DoubleMatrix2D[][], DoubleMatrix2D).

All matrices of a given column within parts must have the same number of columns. All matrices of a given row within parts must have the same number of rows. Otherwise an IllegalArgumentException is thrown. Note that nulls within parts[row,col] are an exception to this rule: they are ignored. Cells are copied. Example:

Code	Result
DoubleMatrix2D[][] parts1 = {    { null, make(2,2,1), null },    { make(4,4,2), null, make(4,3,3) },    { null, make(2,2,4), null } }; System.out.println(compose(parts1));	8 x 9 matrix 0 0 0 0 1 1 0 0 0 0 0 0 0 1 1 0 0 0 2 2 2 2 0 0 3 3 3 2 2 2 2 0 0 3 3 3 2 2 2 2 0 0 3 3 3 2 2 2 2 0 0 3 3 3 0 0 0 0 4 4 0 0 0 0 0 0 0 4 4 0 0 0
DoubleMatrix2D[][] parts3 = {    { identity(3), null, },    { null, identity(3).viewColumnFlip() },    { identity(3).viewRowFlip(), null } }; System.out.println("\n"+make(parts3));	9 x 6 matrix 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0
DoubleMatrix2D A = ascending(2,2); DoubleMatrix2D B = descending(2,2); DoubleMatrix2D _ = null; DoubleMatrix2D[][] parts4 = {    { A, _, A, _ },    { _, A, _, B } }; System.out.println("\n"+make(parts4));	4 x 8 matrix 1 2 0 0 1 2 0 0 3 4 0 0 3 4 0 0 0 0 1 2 0 0 3 2 0 0 3 4 0 0 1 0
DoubleMatrix2D[][] parts2 = {    { null, make(2,2,1), null },    { make(4,4,2), null, make(4,3,3) },    { null, make(2,3,4), null } }; System.out.println("\n"+Factory2D.make(parts2));	IllegalArgumentException A[0,1].cols != A[2,1].cols (2 != 3)

Throws:

IllegalArgumentException - subject to the conditions outlined above.

composeDiagonal

public DoubleMatrix2D composeDiagonal(DoubleMatrix2D A,
                                      DoubleMatrix2D B)

Constructs a diagonal block matrix from the given parts (the direct sum of two matrices). That is the concatenation

A 0
0 B

(The direct sum has A.rows()+B.rows() rows and A.columns()+B.columns() columns). Cells are copied.

Returns:

a new matrix which is the direct sum.

composeDiagonal

public DoubleMatrix2D composeDiagonal(DoubleMatrix2D A,
                                      DoubleMatrix2D B,
                                      DoubleMatrix2D C)

Constructs a diagonal block matrix from the given parts. The concatenation has the form

A 0 0
0 B 0
0 0 C

from the given parts. Cells are copied.

decompose

public void decompose(DoubleMatrix2D[][] parts,
                      DoubleMatrix2D matrix)

Splits a block matrix into its constituent blocks; Copies blocks of a matrix into the given parts. The inverse to method compose(DoubleMatrix2D[][]).

All matrices of a given column within parts must have the same number of columns. All matrices of a given row within parts must have the same number of rows. Otherwise an IllegalArgumentException is thrown. Note that nulls within parts[row,col] are an exception to this rule: they are ignored. Cells are copied. Example:

Code	matrix	--> parts
DoubleMatrix2D matrix = ... ; DoubleMatrix2D _ = null; DoubleMatrix2D A,B,C,D; A = make(2,2); B = make (4,4); C = make(4,3); D = make (2,2); DoubleMatrix2D[][] parts = {    { _, A, _ },    { B, _, C },    { _, D, _ } }; decompose(parts,matrix); System.out.println("\nA = "+A); System.out.println("\nB = "+B); System.out.println("\nC = "+C); System.out.println("\nD = "+D);	8 x 9 matrix 9 9 9 9 1 1 9 9 9 9 9 9 9 1 1 9 9 9 2 2 2 2 9 9 3 3 3 2 2 2 2 9 9 3 3 3 2 2 2 2 9 9 3 3 3 2 2 2 2 9 9 3 3 3 9 9 9 9 4 4 9 9 9 9 9 9 9 4 4 9 9 9	A = 2 x 2 matrix 1 1 1 1 B = 4 x 4 matrix 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 C = 4 x 3 matrix 3 3 3 3 3 3 3 3 3 3 3 3 D = 2 x 2 matrix 4 4 4 4

Throws:

IllegalArgumentException - subject to the conditions outlined above.

demo1

public void demo1()

Demonstrates usage of this class.

demo2

public void demo2()

Demonstrates usage of this class.

descending

public DoubleMatrix2D descending(int rows,
                                 int columns)

Constructs a matrix with cells having descending values. For debugging purposes. Example:

5 4 3 
2 1 0

diagonal

public DoubleMatrix2D diagonal(DoubleMatrix1D vector)

Constructs a new diagonal matrix whose diagonal elements are the elements of vector. Cells values are copied. The new matrix is not a view. Example:

5 4 3 -->
5 0 0
0 4 0
0 0 3

Returns:

a new matrix.

diagonal

public DoubleMatrix1D diagonal(DoubleMatrix2D A)

Constructs a new vector consisting of the diagonal elements of A. Cells values are copied. The new vector is not a view. Example:

5 0 0 9
0 4 0 9
0 0 3 9
--> 5 4 3

Parameters:

A - the matrix, need not be square.

Returns:

a new vector.

identity

public DoubleMatrix2D identity(int rowsAndColumns)

Constructs an identity matrix (having ones on the diagonal and zeros elsewhere).

make

public DoubleMatrix2D make(double[][] values)

Constructs a matrix with the given cell values. values is required to have the form values[row][column] and have exactly the same number of columns in every row.

The values are copied. So subsequent changes in values are not reflected in the matrix, and vice-versa.

Parameters:

values - The values to be filled into the new matrix.

Throws:

IllegalArgumentException - if for any 1 <= row < values.length: values[row].length != values[row-1].length.

make

public DoubleMatrix2D make(double[] values,
                           int rows)

Construct a matrix from a one-dimensional column-major packed array, ala Fortran. Has the form matrix.get(row,column) == values[row + column*rows]. The values are copied.

Parameters:

values - One-dimensional array of doubles, packed by columns (ala Fortran).

rows - the number of rows.

Throws:

IllegalArgumentException - values.length must be a multiple of rows.

make

public DoubleMatrix2D make(int rows,
                           int columns)

Constructs a matrix with the given shape, each cell initialized with zero.

make

public DoubleMatrix2D make(int rows,
                           int columns,
                           double initialValue)

Constructs a matrix with the given shape, each cell initialized with the given value.

random

public DoubleMatrix2D random(int rows,
                             int columns)

Constructs a matrix with uniformly distributed values in (0,1) (exclusive).

repeat

public DoubleMatrix2D repeat(DoubleMatrix2D A,
                             int rowRepeat,
                             int columnRepeat)

C = A||A||..||A; Constructs a new matrix which is duplicated both along the row and column dimension. Example:

0 1
2 3
repeat(2,3) -->
0 1 0 1 0 1
2 3 2 3 2 3
0 1 0 1 0 1
2 3 2 3 2 3

sample

public DoubleMatrix2D sample(int rows,
                             int columns,
                             double value,
                             double nonZeroFraction)

Constructs a randomly sampled matrix with the given shape. Randomly picks exactly Math.round(rows*columns*nonZeroFraction) cells and initializes them to value, all the rest will be initialized to zero. Note that this is not the same as setting each cell with probability nonZeroFraction to value. Note: The random seed is a constant.

Throws:

IllegalArgumentException - if nonZeroFraction < 0 || nonZeroFraction > 1.

See Also:

RandomSampler

sample

public DoubleMatrix2D sample(DoubleMatrix2D matrix,
                             double value,
                             double nonZeroFraction)

Modifies the given matrix to be a randomly sampled matrix. Randomly picks exactly Math.round(rows*columns*nonZeroFraction) cells and initializes them to value, all the rest will be initialized to zero. Note that this is not the same as setting each cell with probability nonZeroFraction to value. Note: The random seed is a constant.

Throws:

IllegalArgumentException - if nonZeroFraction < 0 || nonZeroFraction > 1.

See Also:

RandomSampler