numpy matrix operations | eye() function

Last Updated : 21 Feb, 2019

numpy.matlib.eye() is another function for doing matrix operations in numpy. It returns a matrix with ones on the diagonal and zeros elsewhere.

Syntax : numpy.matlib.eye(n, M=None, k=0, dtype=’float’, order=’C’)

Parameters :
n : [int] Number of rows in the output matrix.
M : [int, optional] Number of columns in the output matrix, defaults is n.
k : [int, optional] Index of the diagonal. 0 refers to the main diagonal, a positive value refers to an upper diagonal, and a negative value to a lower diagonal.Default is 0.
dtype : [optional] Desired output data-type.
order : Whether to store multi-dimensional data in row-major (C-style) or column-major (Fortran-style) order in memory.

Return : A n x M matrix where all elements are equal to zero, except for the k-th diagonal, whose values are equal to one.

Code #1 :

# Python program explaining 
# numpy.matlib.eye() function 
  
# importing matrix library from numpy 
import numpy as geek 
import numpy.matlib 
  
# desired 3 x 3 output matrix  
out_mat = geek.matlib.eye(3, k = 0)  
print ("Output matrix : ", out_mat)  

Output :

Output matrix :  
[[ 1.  0.  0.]
 [ 0.  1.  0.]
 [ 0.  0.  1.]]

Code #2 :

# Python program explaining 
# numpy.matlib.eye() function 
  
# importing numpy and matrix library 
import numpy as geek 
import numpy.matlib 
  
# desired 4 x 5 output matrix  
out_mat = geek.matlib.eye(n = 4, M = 5, k = 1, dtype = int)  
print ("Output matrix : ", out_mat)  

Output :

Output matrix :  
[[0 1 0 0 0]
 [0 0 1 0 0]
 [0 0 0 1 0]
 [0 0 0 0 1]]

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