Python regex to remove text between some pattern

Question

I have text in following format.

|start| this is first para to remove |end|.
this is another text.
|start| this is another para to remove |end|. Again some free text

I want to remove all text in between |start| and |end|

I have tried following re.

regex = '(?<=\|start\|).+(?=\|end\|)'
re.sub(regex, ''. text)

It returns

"Again some free text"

But I expect to return

this is another text. Again some free text

https://stackoverflow.com/questions/3075130/what-is-the-difference-between-and-regular-expressions/3075532#3075532 — Casimir et Hippolyte, Oct 30 '19 at 11:17
Note the start/end delimiters are in lookaround constructs in your pattern and thus will remain in the resulting string after `re.sub`. Try `r'(?s)\|start\|.*?\|end\|\W*'`. Do you also need to remove all newlines? Then, you need to add `.replace('\n', '')` — Wiktor Stribiżew, Oct 30 '19 at 11:17
The regex specified in @WiktorStribiżew comment should work just fine. I've just tested it in https://regex101.com/ . — Evandro Teixeira, Oct 30 '19 at 11:19
@WiktorStribiżew Thank you. No I do not need to remove newlines. — Hima, Oct 30 '19 at 11:47
@Hima Ok, but probably you would still need to `strip()` the result. — Wiktor Stribiżew, Oct 30 '19 at 11:51

score 2 · Accepted Answer · answered Oct 30 '19 at 11:22

Note the start/end delimiters are in lookaround constructs in your pattern and thus will remain in the resulting string after re.sub. You should convert the lookbehind and lookahead into consuming patterns.

Also, you seem to want to remove special chars after the right hand delimiter, so you need to add [^\w\s]* at the end of the regex.

You may use

import re
text = """|start| this is first para to remove |end|.
this is another text.
|start| this is another para to remove |end|. Again some free text"""
print( re.sub(r'(?s)\|start\|.*?\|end\|[^\w\s]*', '', text).replace('\n', '') )
# => this is another text. Again some free text

See the Python demo.

Regex details

(?s) - inline DOTALL modifier
\|start\| - |start| text
.*? - any 0+ chars, as few as possible
\|end\| - |end| text
[^\w\s]* - 0 or more chars other than word and whitespace chars.

score 0 · Answer 2 · answered Oct 30 '19 at 11:27

Try this:

import re

your_string = """|start| this is first para to remove |end|.
this is another text.
|start| this is another para to remove |end|. Again some free text"""

regex = r'(\|start\|).+(\|end\|\.)'

result = re.sub(regex, '', your_string).replace('\n', '')

print(result)

Outputs:

this is another text. Again some free text

Python regex to remove text between some pattern

2 Answers2