Python Substring refers to extracting a smaller portion of a string.

2 years ago

2 minutes

Python Substring is a section of a string. Python string offers different methods for generating a substring, verifying whether it contains a substring, finding the index of a substring, and more. Throughout this tutorial, we will explore different operations pertaining to substrings.

Python substring using a string

Firstly, let us examine two distinct methods of generating a substring.

Make a smaller part of a string.

One option for paraphrasing the given sentence natively could be:

String slicing enables us to generate a subset of characters from a string. By utilizing the split() function, we can create a collection of substrings by specifying a delimiter.

s = 'My Name is Pankaj'

# create substring using slice
name = s[11:]
print(name)

# list of substrings using split
l1 = s.split()
print(l1)

The result is as follows:

Pankaj
['My', 'Name', 'is', 'Pankaj']

python string create substring using slice and split

Verifying the presence of a substring.

To determine if a substring exists within a string, we have the option of using either the in operator or the find() function.

s = 'My Name is Pankaj'

if 'Name' in s:
    print('Substring found')

if s.find('Name') != -1:
    print('Substring found')

Number of times a substring appears

To determine the amount of times a substring appears within a string, we can make use of the count() function.

s = 'My Name is Pankaj'

print('Substring count =', s.count('a'))

s = 'This Is The Best Theorem'
print('Substring count =', s.count('Th'))

Provide one option for paraphrasing the following sentence natively:

“The result obtained or produced.”

Substring count = 3
Substring count = 3

Locate every occurrence of the substring in the source string.

Although there is no predefined function to retrieve all the indexes for a given substring, we can create our own custom function by utilizing the find() function.

def find_all_indexes(input_str, substring):
    l2 = []
    length = len(input_str)
    index = 0
    while index < length:
        i = input_str.find(substring, index)
        if i == -1:
            return l2
        l2.append(i)
        index = i + 1
    return l2


s = 'This Is The Best Theorem'
print(find_all_indexes(s, 'Th'))

python string list of substring indexes positions

You have the option to access the entire Python script and more Python examples directly from our GitHub Repository.