NumPy find() function

In this tutorial, we will cover find() function in the char module of the Numpy Library in Python.

The find() function finds the substring in a given array of string, between the provided range [start, end] returning the first index from where the substring starts.

This function calls str.find function internally in an element-wise manner.

Syntax of find():

The syntax required to use this method is as follows:

numpy.char.find(a, sub, start, end=None)

The above syntax indicates that find() is a function of the char module and takes the parameters as mentioned above.

Parameters:

let us now take a look at the parameters of this function:

• a
  It can either be an input array or an input string.

• sub
  This is a required parameter indicating the substring to search from the input string.

• start, end
  These parameters are optional, both start and end are used to set the boundary within which the substring is to be searched.

Returned Values:

The find() function will return an output array of integers. If the sub is not found then this function will return -1.

Example 1: Substring found

The code snippet is as follows where we will use find() function:

import numpy as np 

arr = ['AAAabbbbbxcccccyyysss', 'AAAAAAAaattttdsxxxxcccc', 'AAaaxxxxcccutt', 'AAaaxxccxcxXDSDdscz'] 
print ("The array is :\n ", arr) 

print ("\nThe find of 'xc'", np.char.find(arr, 'xc')) 
print ("The find of 'xc'", np.char.find(arr, 'xc', start = 3)) 
print ("The find of 'xc'", np.char.find(arr, 'xc', start = 8)) 

Example 2: Some substrings not found

import numpy as np 

arr = ['AAAabbbbbxcccccyyysss', 'AAAAAAAaattttds', 'AAaaxcutt', 'AAaaxXDSDdscz'] 
print ("The array is :\n ", arr) 

print ("\nThe find of 'xc'", np.char.find(arr, 'xc')) 
print ("The find of 'xc'", np.char.find(arr, 'xc', start = 8)) 

The array is :
['AAAabbbbbxcccccyyysss', 'AAAAAAAaattttds', 'AAaaxcutt', 'AAaaxXDSDdscz']

The find of 'xc' [ 9 -1 4 -1]
The find of 'xc' [ 9 -1 -1 -1]

Summary

In this tutorial, we learned about find() function of the Numpy Library along with a few code examples. If you want to try a few code examples you can do so in our Python code compiler.