根据它们所在的位置用两个不同的字符串替换一个子字符串

Question

Let's say I have a string with some asterisks:

myvar = "this is an *italicized* substring"

I want to replace *italicized* with {i}italicized{/i} for the project I'm working on, txt2rpy, but I'm not sure how to have two different substrings being replaced depending on what order they come in.

Answer 1

You can use a regular expression to substitute the pattern as a whole:

re.sub(r'\*(.*?)\*', r'{i}\1{/i}', myvar)

In the regexp:

• \\* matches a literal * (used twice)
• (.*?) matches any number of any (non-newline) characters, as few as possible - it is also in a capture group

In the replacement:

• {i} and {/i} are literals
• \\1 means to put what was in the first (and in this case, only) capture group

This gives:

>>> import re
>>> myvar = "this is an *italicized* substring"
>>> print(re.sub(r'\*(.*?)\*', r'{i}\1{/i}', myvar))
this is an {i}italicized{/i} substring

If you have more than one occurrence of the pattern, that will work also:

myvar = "this is an *italicized* substring, and here is *another* one"

will give

this is an {i}italicized{/i} substring, and here is {i}another{/i} one

Answer 2

You can use re.sub with capture groups for that:

import re

txt = "this is an *italicized* substring"

res = re.sub(r"\*([^*]+)\*", "{i}\g<1>{/i}", txt)

will have res as:

this is an {i}italicized{/i} substring

---

This pattern is pretty basic: It matches a literal * , then character not an asterisk, then another literal * . The main point here is that we use a capture group to catch the word part.

Then we simply substitute the full match with the word we saved (accessed by \\g<1> ) surrounded with your wanted characters.

---

Demo here

Answer 3

创建一个用于解析的循环并保持一个计数器进行跟踪，每当计数器保持第二个标签并用第一个标签替换奇数时。

Answer 4

you could you use a for loop and say

myvar = "this is an *italicized* substring"
positions = []
for x in range(len(myvar)):
    if myvar[x] == "*":
       positions.append(x)
inAsteriks = myvar[0:positions[0]] + "{i}" + myvar[positions[0]+1:positions[1]] + "{/i}" + myvar[positions[0]+1:]