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# 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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