NumPy Eye Function

Introduction

In this lab, we will learn about the NumPy eye() function, which creates a matrix with diagonal elements as 1 and all other elements as 0. We will cover the syntax, parameters along with some examples to understand this function.

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Skills Graph

Import the NumPy library

Before using NumPy library and its functions we need to import it. We will import it using the following code:

import numpy as np

Create a matrix using eye() function

We will create a matrix using eye() function. This function returns a matrix with diagonal elements as 1 and all other elements as 0.

x = np.eye(4,4)
print(x)

Output:

array([[1., 0., 0., 0.],
       [0., 1., 0., 0.],
       [0., 0., 1., 0.],
       [0., 0., 0., 1.]])

Create a matrix with diagonal elements off the main diagonal

We can create a matrix with diagonal elements off the main diagonal by using the k parameter. If k=1 then diagonal will be shifted to one position to the right and if k=-1 then diagonal will be shifted to one position to the left. k=0 represents main diagonal.

y = np.eye(4,4,k=1)
print(y)

Output:

array([[0., 1., 0., 0.],
       [0., 0., 1., 0.],
       [0., 0., 0., 1.],
       [0., 0., 0., 0.]])

Create a matrix of integer datatype

We can create a matrix of integer datatype by specifying dtype parameter as int.

z = np.eye(4,4,dtype=int)
print(z)

Output:

array([[1, 0, 0, 0],
       [0, 1, 0, 0],
       [0, 0, 1, 0],
       [0, 0, 0, 1]])

Create a matrix with different number of rows and columns

We can create a matrix of any number of rows and columns by specifying the number of rows and columns in the eye() function.

w = np.eye(3,4,k=-1,dtype=int)
print(w)

Output:

array([[0, 0, 0, 0],
       [1, 0, 0, 0],
       [0, 1, 0, 0]])

Difference between eye() and identity() functions

The identity() function creates a square matrix with diagonal elements as 1 and all other elements as 0. Whereas the eye() function creates a matrix of any number of rows and columns with diagonal elements as 1 and all other elements as 0.

i = np.identity(4,dtype=int)
print(i)

output:
[[1 0 0 0]
 [0 1 0 0]
 [0 0 1 0]
 [0 0 0 1]]

Summary

In this lab, we learned about the NumPy eye() function which creates a matrix with diagonal elements as 1 and all other elements as 0. We covered the syntax, parameters along with some examples to understand this function.