Matrix Library using Numpy

NumPy package contains a Matrix library numpy.matlib. This module has functions that return matrices instead of ndarray objects.

matlib.empty()

The matlib.empty() function returns a new matrix without initializing the entries. The function takes the following parameters.

numpy.matlib.empty(shape, dtype, order)

Where,

shape
int or tuple of int defining the shape of the new matrix
Dtype
Optional. Data type of the output
order
C or F

Example

import numpy.matlib
import numpy as np
print( np.matlib.empty((2,2)))
# filled with random data

It will produce the following output −

[[ 2.12199579e-314, 4.24399158e-314]
[ 4.24399158e-314, 2.12199579e-314]]

numpy.matlib.zeros()

This function returns the matrix filled with zeros.

import numpy.matlib
import numpy as np
print( np.matlib.zeros((2,2)))

It will produce the following output −

[[ 0. 0.]
[ 0. 0.]]

numpy.matlib.ones()

This function returns the matrix filled with 1s.

import numpy.matlib
import numpy as np
print( np.matlib.ones((2,2)))

It will produce the following output −

[[ 1. 1.]
[ 1. 1.]]

numpy.matlib.eye()

This function returns a matrix with 1 along the diagonal elements and the zeros elsewhere. The function takes the following parameters.

numpy.matlib.eye(n, M,k, dtype)

Where,

n
The number of rows in the resulting matrix
M
The number of columns, defaults to n
k
Index of diagonal
dtype
Data type of the output

Example

import numpy.matlib
import numpy as np
print( np.matlib.eye(n = 3, M = 4, k = 0, dtype = float))

It will produce the following output −

[[ 1. 0. 0. 0.]
[ 0. 1. 0. 0.]
[ 0. 0. 1. 0.]]

numpy.matlib.identity()

The numpy.matlib.identity() function returns the Identity matrix of the given size. An identity matrix is a square matrix with all diagonal elements as 1.

import numpy.matlib
import numpy as np
print( np.matlib.identity(5, dtype = float))

It will produce the following output −

[[ 1. 0. 0. 0. 0.]
[ 0. 1. 0. 0. 0.]
[ 0. 0. 1. 0. 0.]
[ 0. 0. 0. 1. 0.]
[ 0. 0. 0. 0. 1.]]

numpy.matlib.rand()

The numpy.matlib.rand() function returns a matrix of the given size filled with random values.

Example

import numpy.matlib
import numpy as np
print( np.matlib.rand(3,3))

It will produce the following output −

[[ 0.82674464 0.57206837 0.15497519]
[ 0.33857374 0.35742401 0.90895076]
[ 0.03968467 0.13962089 0.39665201]]

Note that a matrix is always two-dimensional, whereas ndarray is an n-dimensional array. Both the objects are inter-convertible.

Example

import numpy.matlib
import numpy as np
i = np.matrix('1,2;3,4')
print( i)

It will produce the following output −

[[1 2]
[3 4]]

Example

import numpy.matlib
import numpy as np
j = np.asarray(i)
print j

It will produce the following output −

[[1 2]
[3 4]]

Example

import numpy.matlib
import numpy as np
k = np.asmatrix (j)
print( k)

It will produce the following output −

[[1 2]
[3 4]]