In this article, we will discuss different ways to replace the last N characters of a string with another substring in Python. Table Of Contents
Suppose we have a string,
"Sample String"
We want to replace the last 3 characters in this string. After replacement, the final string should be like,
"Sample StrXXX"
There are different techniques to do this. Let’s discuss them one by one.
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Using Indexing
To replace the last N characters in a string using indexing, select all characters of string except the last n characters i.e. str[:-n]. Then add replacement substring after these selected characters and assign it back to the original variable. It will give us an effect that we have replaced the last N characters in string with a new substring.
For example: Replace last 3 characters in a string with “XXX”
strValue = 'Sample String' n = 3 replacementStr = 'XXX' # Replace last 3 characters in string with 'XXX' strValue = strValue[:-n] + replacementStr print[strValue]
Output:
Sample StrXXX
It replaced the last 3 characters in string with “XXX”.
Using rsplit[] and join[]
Split the string but from reverse direction i.e. starting from the end and while moving towards the front of string. Use the last N characters of string as delimeter and 1 as the max count of split i.e. str.rsplit[str[-n:], 1] . It returns a sequence of all characters in string except the last N characters. Then join these characters with the substring ‘XXX’ using the join[] function.
For example: Replace last 3 characters in a string with “XXX”
strValue = 'Sample String' n = 3 replacementStr = 'XXX' # Replace last 3 characters in string with 'XXX' strValue = replacementStr.join[strValue.rsplit[strValue[-n:], 1]] print[strValue]
Output:
Sample StrXXX
It replaced the last 3 characters in string with “XXX”.
Using Regex
The regex module provides a function regex.sub[pattern, replacement_str, original_str] . It helps to replace the substrings in string that matches the given regex pattern.
To replace the last N character in a string, pass the regex pattern “.{N}$” and replacement substring in the sub[] function. This regex pattern will match only the last N characters in the string and those will be replaced by the given substring.
For example: Replace last 3 characters in a string with “XXX”
import re
strValue = 'Sample String'
# Replace last 3 characters in string with 'XXX'
strValue = re.sub[r'.{3}$', 'XXX', strValue]
print[strValue]Output:
Sample StrXXX
Summary:
We learned about three different ways to replace the last N characters in a string in Python.
How do I remove the last character from a string?
"abcdefghij" → "abcdefghi"
Mateen Ulhaq
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asked Mar 18, 2013 at 13:33
3
Simple:
my_str = "abcdefghij"
my_str = my_str[:-1]
Try the following code snippet to better understand how it works by casting the string as a list:
str1 = "abcdefghij"
list1 = list[str1]
print[list1]
list2 = list1[:-1]
print[list2]
In case, you want to accept the string from the user:
str1 = input["Enter :"]
list1 = list[str1]
print[list1]
list2 = list1[:-1]
print[list2]
To make it take away the last word from a sentence [with words separated by whitespace like space]:
str1 = input["Enter :"]
list1 = str1.split[]
print[list1]
list2 = list1[:-1]
print[list2]
Hari
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answered Mar 18, 2013 at 13:34
CyrilleCyrille
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5
What you are trying to do is an extension of string slicing in Python:
Say all strings are of length 10, last char to be removed:
>>> st[:9]
'abcdefghi'
To remove last N characters:
>>> N = 3
>>> st[:-N]
'abcdefg'
answered Aug 30, 2019 at 9:56
Anshul GoyalAnshul Goyal
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The simplest solution for you is using string slicing.
Python 2/3:
source[0: -1] # gets all string but not last char
Python 2:
source = 'ABC'
result = "{}{}".format[{source[0: -1], 'D']
print[result] # ABD
Python 3:
source = 'ABC'
result = f"{source[0: -1]}D"
print[result] # ABD
answered Jun 8, 2021 at 13:38
NicoNico
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So there is a function called rstrip[] for stuff like this. You enter the value you want to delete, in this case last element so string[-1] :
string = "AbCdEf"
newString = string.rstrip[string[-1]]
print[newString]
If you runt his code you shouul see the 'f' value is deleted.
OUTPUT: AbCdE
answered May 3 at 18:57
Using slicing, one can specify the start and stop indexes to extract part of a string s. The format is s[start:stop]. However, start = 0 by default. So, we only need to specify stop.
Using stop = 3:
>>> s = "abcd"
>>> s[:3]
'abc'
Using stop = -1 to remove 1 character from the end [BEST METHOD]:
>>> s = "abcd"
>>> s[:-1]
'abc'
Using stop = len[s] - 1:
>>> s = "abcd"
>>> s[:len[s] - 1]
'abc'
answered Apr 25 at 0:14
Mateen UlhaqMateen Ulhaq
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