Python 在字符串中查找最后一次出现的子字符串，替换它
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Finding last occurrence of substring in string, replacing that
提问by Adam Magyar
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.
所以我有一长串相同格式的字符串，我想找到最后一个“。” 每个字符中的字符，并将其替换为“. - ”。我试过使用 rfind，但我似乎无法正确利用它来做到这一点。
采纳答案by Aditya Sihag
This should do it
这应该做
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:]
回答by Tim Pietzcker
I would use a regex:
我会使用正则表达式：
import re
new_list = [re.sub(r"\.(?=[^.]*$)", r". - ", s) for s in old_list]
回答by Alex L
Na?ve approach:
天真的方法：
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:
Aditya Sihag 的回答是rfind：
pos = a.rfind('.')
a[:pos] + '. -' + a[pos+1:]
回答by Varinder Singh
To replace from the right:
从右侧替换：
def replace_right(source, target, replacement, replacements=None):
return replacement.join(source.rsplit(target, replacements))
In use:
正在使用：
>>> replace_right("asd.asd.asd.", ".", ". -", 1)
'asd.asd.asd. -'
回答by mazs
A one liner would be :
一个班轮将是：
str=str[::-1].replace(".",".-",1)[::-1]
str=str[::-1].replace(".",".-",1)[::-1]
回答by Arpan Saini
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
# 如果你想找到任何字符串最后一次出现的索引，在我们的例子中，我们#will找到最后一次出现的索引 with
index = a.rfind("with")
# the result will be 44, as index starts from 0.
# 结果将是 44，因为索引从 0 开始。
回答by bambuste
You can use the function below which replaces the first occurrence of the word from right.
您可以使用下面的函数来替换右边第一个出现的单词。
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]
