DoubleFactory2D
cern.colt.matrix.tdouble

## Class DoubleFactory2D

• All Implemented Interfaces:
Serializable, Cloneable

```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.

 Construction Use idioms like DoubleFactory2D.dense.make(4,4) to construct dense matrices, DoubleFactory2D.sparse.make(4,4) to construct sparse matrices. Construction with initial values Use other make methods to construct matrices with given initial values. Appending rows and columns Use methods `appendColumns`, `appendRows` and `repeat` to append rows and columns. General block matrices Use methods `compose` and `decompose` to work with general block matrices. Diagonal matrices Use methods `diagonal(vector)`, `diagonal(matrix)` and `identity` to work with diagonal matrices. Diagonal block matrices Use method `composeDiagonal` to work with diagonal block matrices. Random Use methods `random` and `sample` to construct random matrices.

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); ... ```
See Also:
Serialized Form
• ### Field Summary

Fields
Modifier and Type Field and Description
`static DoubleFactory2D` `dense`
A factory producing dense matrices.
`static DoubleFactory2D` `sparse`
A factory producing sparse hash matrices.
• ### Method Summary

Methods
Modifier and Type Method and Description
`DoubleMatrix2D` ```appendColumn(DoubleMatrix2D A, DoubleMatrix1D b)```
C = A||b; Constructs a new matrix which is the column-wise concatenation of two other matrices.
`DoubleMatrix2D` ```appendColumns(DoubleMatrix2D A, DoubleMatrix2D B)```
C = A||B; Constructs a new matrix which is the column-wise concatenation of two other matrices.
`DoubleMatrix2D` ```appendRow(DoubleMatrix2D A, DoubleMatrix1D b)```
C = A||b; Constructs a new matrix which is the row-wise concatenation of two other matrices.
`DoubleMatrix2D` ```appendRows(DoubleMatrix2D A, DoubleMatrix2D B)```
C = A||B; Constructs a new matrix which is the row-wise concatenation of two other matrices.
`DoubleMatrix2D` ```ascending(int rows, int columns)```
Constructs a matrix with cells having ascending values.
`DoubleMatrix2D` `compose(DoubleMatrix2D[][] parts)`
Constructs a block matrix made from the given parts.
`DoubleMatrix2D` ```composeBidiagonal(DoubleMatrix2D A, DoubleMatrix2D B)```
Constructs a bidiagonal block matrix from the given parts.
`DoubleMatrix2D` ```composeDiagonal(DoubleMatrix2D A, DoubleMatrix2D B)```
Constructs a diagonal block matrix from the given parts (the direct sum of two matrices).
`DoubleMatrix2D` ```composeDiagonal(DoubleMatrix2D A, DoubleMatrix2D B, DoubleMatrix2D C)```
Constructs a diagonal block matrix from the given parts.
`void` ```decompose(DoubleMatrix2D[][] parts, DoubleMatrix2D matrix)```
Splits a block matrix into its constituent blocks; Copies blocks of a matrix into the given parts.
`void` `demo1()`
Demonstrates usage of this class.
`void` `demo2()`
Demonstrates usage of this class.
`DoubleMatrix2D` ```descending(int rows, int columns)```
Constructs a matrix with cells having descending values.
`DoubleMatrix2D` `diagonal(double[] vector)`
Constructs a new diagonal matrix whose diagonal elements are the elements of vector.
`DoubleMatrix2D` `diagonal(DoubleMatrix1D vector)`
Constructs a new diagonal matrix whose diagonal elements are the elements of vector.
`DoubleMatrix1D` `diagonal(DoubleMatrix2D A)`
Constructs a new vector consisting of the diagonal elements of A .
`DoubleMatrix2D` `identity(int rowsAndColumns)`
Constructs an identity matrix (having ones on the diagonal and zeros elsewhere).
`DoubleMatrix2D` `make(double[][] values)`
Constructs a matrix with the given cell values.
`DoubleMatrix2D` ```make(double[] values, int rows)```
Construct a matrix from a one-dimensional column-major packed array, ala Fortran.
`DoubleMatrix2D` ```make(int rows, int columns)```
Constructs a matrix with the given shape, each cell initialized with zero.
`DoubleMatrix2D` ```make(int rows, int columns, double initialValue)```
Constructs a matrix with the given shape, each cell initialized with the given value.
`DoubleMatrix2D` ```random(int rows, int columns)```
Constructs a matrix with uniformly distributed values in (0,1) (exclusive).
`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.
`DoubleMatrix2D` ```sample(DoubleMatrix2D matrix, double value, double nonZeroFraction)```
Modifies the given matrix to be a randomly sampled matrix.
`DoubleMatrix2D` ```sample(int rows, int columns, double value, double nonZeroFraction)```
Constructs a randomly sampled matrix with the given shape.
• ### Methods inherited from class cern.colt.PersistentObject

`clone`
• ### Methods inherited from class java.lang.Object

`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`
• ### Field Detail

• #### dense

`public static final DoubleFactory2D dense`
A factory producing dense matrices.
• #### sparse

`public static final DoubleFactory2D sparse`
A factory producing sparse hash matrices.
• ### Method Detail

• #### appendColumn

```public DoubleMatrix2D appendColumn(DoubleMatrix2D A,
DoubleMatrix1D b)```
C = A||b; Constructs a new matrix which is the column-wise concatenation of two other matrices.
```   0 1 2
3 4 5
appendColumn
6
8
-->
0 1 2 6
3 4 5 8

```
• #### 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

```
• #### appendRow

```public DoubleMatrix2D appendRow(DoubleMatrix2D A,
DoubleMatrix1D b)```
C = A||b; Constructs a new matrix which is the row-wise concatenation of two other matrices.
```   0 1
2 3
4 5
appendRow
6 7
-->
0 1
2 3
4 5
6 7

```
• #### 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].columns != A[2,1].columns (2 != 3)
Throws:
`IllegalArgumentException` - subject to the conditions outlined above.
• #### composeBidiagonal

```public DoubleMatrix2D composeBidiagonal(DoubleMatrix2D A,
DoubleMatrix2D B)```
Constructs a bidiagonal 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.
Parameters:
`A` - bidiagonal matrix
`B` - bidiagonal matrix
Returns:
bidiagonal matrix
• #### 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(double[] 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 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,
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(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(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(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:
`DoubleRandomSampler`
• #### 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:
`DoubleRandomSampler`

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