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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,
| Sr.No. | Parameter & Description |
|---|---|
| 1 |
shape int or tuple of int defining the shape of the new matrix |
| 2 |
Dtype Optional. Data type of the output |
| 3 |
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,
| Sr.No. | Parameter & Description |
|---|---|
| 1 |
n The number of rows in the resulting matrix |
| 2 |
M The number of columns, defaults to n |
| 3 |
k Index of diagonal |
| 4 |
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]]
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