🔒 Regex Expression | Python | Page 1

celest field Jan 17, 2025, 2:04 PM

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Hello there,
I am stuck on a regex problem;
tried looking into regex testers online.
It looks like it should work, but it doesn't? (burnt out lemon_pleading )

Anyways, any/all help would be appreciated y'all 👋

Problem :
I am trying to replace certain parts
in a (multi-line) string that don't contain the sequence MK.

parts are separated by a string,
for now; lets say it's BBBB

Context :
"sample" text -

some random text

BBBB

abcdefg
*MK*
xyz

BBBB

more text

BBBB

*MK*
xyz

transforms into –

[Removed Text]

abcdefg
*MK*
xyz

[Removed Text]

*MK*
xyz

Attempt/s :
I've attempted using negative lookahead, but to no avail.

"B+(?!MK)[^B]+B*"

"(?!MK)B+.+?B*"

"B+[^B]+B*(?<!MK)"

ruby tigerBOT Jan 17, 2025, 2:04 PM

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celest field Hello there, I am stuck on a regex problem; tried looking into regex testers onl...

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@celest field

Python help channel opened

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fading path Jan 17, 2025, 2:13 PM

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Does it have to be regex? It doesn't seem too complicated without

true scaffold Jan 17, 2025, 2:14 PM

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you could split the string at BBBB and then check each string for MK

celest field Jan 17, 2025, 2:14 PM

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I've done a workaround, by splitting the text into chunks (BBBB being the separator); then looking if MK exists in each chunk

fading path Jan 17, 2025, 2:14 PM

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"".join(section for section in text.split("BBBB") if "*MK*" in section)

celest field Jan 17, 2025, 2:17 PM

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Reason being as for why i am looking more into regex - is because I had a previous version that utilized regex for similar simpler process.

celest field Jan 17, 2025, 2:20 PM

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celest field Hello there, I am stuck on a regex problem; tried looking into regex testers onl...

which in turn got more complicated as time went on, and it became ^this .

Just me looking if there's any way to modify the (older) expression and end it there; instead of a workaround . . .

zenith tapir Jan 17, 2025, 2:28 PM

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Yeahhh I would avoid using regex for that if you can

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something like (^|BBBB)([\n\r\w ](?!MK))* might work for finding the places you want to remove, not sure how to invert it to keep them though

shrewd pilot Jan 17, 2025, 2:45 PM

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matching the places to remove is what they want, no? so they can just re.sub it
I agree with the others on not solely using regex, especially if this is gonna get modified again in the future

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not that it's impossible to do it with regex, just unnecessary complexity

celest field Jan 17, 2025, 3:10 PM

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shrewd pilot not that it's impossible to do it with regex, just unnecessary complexity

yeah, it probably is (an unneccesary complexity).

Well, thanks a lot people.
this was quite the help ^.^

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I think I'd just do the workaround and call it a day.
thanks again for all the help 👋

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!close

ruby tigerBOT Jan 17, 2025, 3:11 PM

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Python help channel closed

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#🔒 Regex Expression