Python | Get the string after occurrence of given substring

The problem involves getting the string that is occurring after the substring has been found. Let's discuss certain ways in which this task can be performed using Python.

Using partition()

To extract the portion of a string that occurs after a specific substring partition() method is an efficient and straightforward solution. It splits the string into three parts: the portion before the substring, the substring itself, and the portion after the substring.

# string
s = "GeeksforGeeks is best for geeks"
# split word
w = 'best'
_, _, res = s.partition(w)
print(res)

 for geeks

Explanation:

• _.partition(w) splits the string s into three parts. The text before the word w, the word w itself, and the text after w.
• _, _, res = s.partition(w): This breaks the result into three parts. The first two parts are ignored (_), and res stores the text after the word w.

Using split()

split() method divides a string into a list based on a specified delimiter. By using split() with the substring, we can easily get the part of the string that comes after it.

s = "GeeksforGeeks is best for geeks"
w= 'best'
# Split the string and get the part after the substring
res = s.split(w, 1)
result = res[1] if len(res) > 1 else ""
print(result)

 for geeks

Explanation:

• split(spl_word, 1) splits the string at the first occurrence of best, returning two parts.
• Part after best is stored in result. If best isn't found, an empty string is returned.

Using find()

find() method is used to locate the starting index of a substring in a string. Once the index is found, slicing can be applied to extract the part of the string that comes after the substring.

s= "GeeksforGeeks is best for geeks"
w= 'best'
# Find the starting index of the substring
start_idx = s.find(w)
# Slice the string from the end of the substring
res = s[start_idx + len(w):] if start_idx != -1 else ""
print(res)

 for geeks

Explanation:

• find(w) returns the starting index of best in the string. If best is not found, it returns -1.
• If the substring is found, slicing is used to extract everything after the substring by adding its length to the starting index.
• If the substring is not found, an empty string is returned.

Using re

This approach uses a regular expression to search for the first occurrence of the substring in the input string, and returns the portion of the string after the substring if it is found. If the substring is not found, an empty string is returned.

import re
s= "GeeksforGeeks is best for geeks"
w = 'best'
res = re.split(w, s, maxsplit=1)
result = res[1] if len(res) > 1 else ""
print(result)

 for geeks

Explanation:

• maxsplit=1 : This ensures that only the first occurrence of 'best' is considered for splitting.
• len(res) > 1 : This condition ensures the code doesn’t throw an IndexError if the substring is not found in the string.