NumPy eye() function

In this tutorial, we will cover numpy.matlib.eye() function of the Numpy library.

The numpy.matlib.eye() function is used to return a matrix with all the diagonal elements initialized to 1 and with zero value elsewhere.

The numpy.matlib is a matrix library used to configure matrices instead of ndarray objects.

Syntax of matlib.eye():

The required syntax to use this function is as follows:

numpy.matlib.eye(n, m, k, dtype,order)   

Parameters:

Let us now cover the parameters used with this function:

• n
  This parameter is used to represent the number of rows in the resulting matrix.

• m
  This parameter is used to represent the number of columns and the default value is n.

• k
  This parameter is used to indicate an index of diagonal,value of this parameter is 0 by default if value of k>0 it means diagonal is above the main diagonal or vice versa.

• dtype
  This parameter is used to indicate the data type of the matrix. The default value of this parameter is float. This is an optional parameter.

• order
  This is an optional parameter that is used to indicate the insertion order of the matrix. It mainly indicates whether to store the result in C- or Fortran-contiguous order, The default value is 'C'.

Returned Values:

This method will return a n x M matrix where all elements are equal to zero, except for the kth diagonal, whose values are equal to one.

Example 1:

Given below is a basic example for the understanding of this function:

import numpy as np  
import numpy.matlib  
  
x = numpy.matlib.eye(n = 4, M = 3, k = 0, dtype = int)
print("The Output is :")
print(x)

The Output is :
[[1 0 0]
[0 1 0]
[0 0 1]
[0 0 0]]

Example 2:

Let's take another example, to create a matrix of different dimensions.

import numpy as np  
import numpy.matlib  
  
x = numpy.matlib.eye(n = 5, M = 4, k = 1, dtype = int)
print("The Output is :")
print(x)

The Output of the above code:

Difference between eye() and identity():

There is a difference between the Numpy identity() function and eye() function and that is, the identity function returns a square matrix having ones on the main diagonal like this:

while the eye() function returns a matrix having 1 on the diagonal and 0 elsewhere with respect to the value of K parameter, if value of K > 0 then it implies the diagonal above main diagonal and vice-versa.

Summary

In this tutorial we learned about numpy.eye() mathematical function of the Numpy library. We also covered its syntax, parameters as well as the value returned by this function along with a few examples.