Finding last occurrence of substring in string, replacing that
Question:
So I have a long list of strings in the same format, and I want to find the last “.” character in each one, and replace it with “. – “. I’ve tried using rfind, but I can’t seem to utilize it properly to do this.
Answers:
I would use a regex:
import re
new_list = [re.sub(r".(?=[^.]*$)", r". - ", s) for s in old_list]
This should do it
old_string = "this is going to have a full stop. some written sstuff!"
k = old_string.rfind(".")
new_string = old_string[:k] + ". - " + old_string[k+1:]
Naïve approach:
a = "A long string with a . in the middle ending with ."
fchar = '.'
rchar = '. -'
a[::-1].replace(fchar, rchar[::-1], 1)[::-1]
Out[2]: 'A long string with a . in the middle ending with . -'
Aditya Sihag’s answer with a single rfind:
pos = a.rfind('.')
a[:pos] + '. -' + a[pos+1:]
To replace from the right:
def replace_right(source, target, replacement, replacements=None):
return replacement.join(source.rsplit(target, replacements))
In use:
>>> replace_right("asd.asd.asd.", ".", ". -", 1)
'asd.asd.asd. -'
A one liner would be :
str=str[::-1].replace(".",".-",1)[::-1]
a = "A long string with a . in the middle ending with ."
# if you want to find the index of the last occurrence of any string, In our case we #will find the index of the last occurrence of with
index = a.rfind("with")
# the result will be 44, as index starts from 0.
You can use the function below which replaces the first occurrence of the word from right.
def replace_from_right(text: str, original_text: str, new_text: str) -> str:
""" Replace first occurrence of original_text by new_text. """
return text[::-1].replace(original_text[::-1], new_text[::-1], 1)[::-1]
So I have a long list of strings in the same format, and I want to find the last “.” character in each one, and replace it with “. – “. I’ve tried using rfind, but I can’t seem to utilize it properly to do this.
I would use a regex:
import re
new_list = [re.sub(r".(?=[^.]*$)", r". - ", s) for s in old_list]
This should do it
old_string = "this is going to have a full stop. some written sstuff!"
k = old_string.rfind(".")
new_string = old_string[:k] + ". - " + old_string[k+1:]
Naïve approach:
a = "A long string with a . in the middle ending with ."
fchar = '.'
rchar = '. -'
a[::-1].replace(fchar, rchar[::-1], 1)[::-1]
Out[2]: 'A long string with a . in the middle ending with . -'
Aditya Sihag’s answer with a single rfind:
pos = a.rfind('.')
a[:pos] + '. -' + a[pos+1:]
To replace from the right:
def replace_right(source, target, replacement, replacements=None):
return replacement.join(source.rsplit(target, replacements))
In use:
>>> replace_right("asd.asd.asd.", ".", ". -", 1)
'asd.asd.asd. -'
A one liner would be :
str=str[::-1].replace(".",".-",1)[::-1]
a = "A long string with a . in the middle ending with ."
# if you want to find the index of the last occurrence of any string, In our case we #will find the index of the last occurrence of with
index = a.rfind("with")
# the result will be 44, as index starts from 0.
You can use the function below which replaces the first occurrence of the word from right.
def replace_from_right(text: str, original_text: str, new_text: str) -> str:
""" Replace first occurrence of original_text by new_text. """
return text[::-1].replace(original_text[::-1], new_text[::-1], 1)[::-1]