Python | Ways to find nth occurrence of substring in a string
Given a string and a substring, write a Python program to find the nth occurrence of the string. Let’s discuss a few methods to solve the given task.
Method #1: Using re
# Python code to demonstrate # to find nth occurrence of substring import re # Initialising values ini_str = "abababababab"substr = "ab"occurrence = 4 # Finding nth occurrence of substring inilist = [m.start() for m in re.finditer(r"ab", ini_str)] if len(inilist)>= 4: # Printing result print ("Nth occurrence of substring at", inilist[occurrence-1]) else: print ("No {} occurrence of substring lies in given string".format(occurrence)) |
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Method #2: Using find() method
# Python code to demonstrate # to find nth occurrence of substring # Initialising values ini_str = "abababababab"sub_str = "ab"occurrence = 4 # Finding nth occurrence of substring val = -1for i in range(0, occurrence): val = ini_str.find(sub_str, val + 1) # Printing nth occurrence print ("Nth occurrence is at", val) |
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Method #3: Using startswith() and list comprehension
# Python code to demonstrate # to find nth occurrence of substring # Initialising values ini_str = "abababababab"substr = "ab"occurrence = 4 # Finding nth occurrence of substring inilist = [i for i in range(0, len(ini_str)) if ini_str[i:].startswith(substr)] if len(inilist)>= 4: # Printing result print ("Nth occurrence of substring at", inilist[occurrence-1]) else: print ("No {} occurrence of substring lies in given string".format(occurrence)) |
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