Matching alphanumeric words, mentions or emails with Python regex

Question

I've already read this and this and this and lots of others. They don't answer to my problem.

I'd like to filter a string that may contain emails or strings starting by "@" (like emails but without the text before the "@"). I've tested many ones but one of the simplest that begins to get close is:

import re
re.split(r'(@)', "test @aa test2 @bb @cc t-es @dd-@ee, test@again")
Out[40]: 
['test ', '@', 'aa test2 ', '@', 'bb ', '@', 'cc t-es ', '@', 'dd-', '@', 'ee, test', '@', 'again']

I'm looking for the right regexp that could give me:

['test ', '@aa', 'test2 ', '@bb ', '@cc', 't-es ', '@dd-', '@ee', 'test@again']

Are you sure you want `'@ee', 'test@again'` and not `'@ee, test@again'` (single item)? Should the comma be considered as a "stop" char? — Wiktor Stribiżew, May 24 '19 at 08:42
@WiktorStribiżew Nope it gives me one item like `@aa test2 ` whereas I should have 2 items: `@aa` and `test2` — Olivier Pons, May 24 '19 at 09:26
Then please check your question and edit. We do not know what result you expect and why. — Wiktor Stribiżew, May 24 '19 at 09:27
@MichaWiedenmann I'm looking exactly for `@aa`, `@bb`, `@dd-`, `@ee`, `test@again` — Olivier Pons, May 24 '19 at 11:26
Does `re.findall(r'[^\s@]*@[^\s@]+', s)` work for you? If not, why? Please explain the rules in the question. — Wiktor Stribiżew, May 24 '19 at 12:08
The questions you menioned did not work for you because you had quite a different problem, it is not about splitting with some delimiters to keep. — Wiktor Stribiżew, Jun 26 '20 at 10:01

Işık Kaplan · Answer 1 · 2019-05-24T11:35:18.617

1

Why try to split when you can go "yo regex, give me all that matches":

test = "test @aa test2 @bb @cc t-es @dd-@ee, test@again"


import re

print(
    re.findall("[^\s@]*?@?[^@]* |[^@]*@[^\s@]*", test)
)
# ['test ', '@aa test2 ', '@bb ', '@cc t-es ', '@dd-', '@ee, ', 'test@again']

I tried but I couldn't make the regex any smaller, but at least it works and who expects regex to be small anyway

As per the OP's new requirements(or corrected requirements)

[^\s@]*?@?[^\s@]* |[^@]*@[^\s@]*

edited May 24 '19 at 11:35

answered May 24 '19 at 09:12

Işık Kaplan

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You are on the right path, but I was wrong in my question, I've edited it, could you check it again? Thank you very much! – Olivier Pons May 24 '19 at 11:27
You need to decide `'@aa test2 '` you either get this, or `'@cc', 't-es '` this, if we are gonna split on the white space like the second, first one would get split too, if we want them together, the second one would be together too. – Işık Kaplan May 24 '19 at 11:29
OMG I was wrong again, sorry, I've edited it, could you check it again? Thank you very much! – Olivier Pons May 24 '19 at 11:33
I'm almost there: `re.findall("[^@\s]*@[^\[@!\?\]\s]*", "test. @aa test2 t-es @dd-@ee, @ff. @ff! test@again.com ns@gmail.com")` but I want to stop before unwanted chars like `!` or `?` – Olivier Pons May 24 '19 at 11:36
It matches all you want, what is the problem? do you want match the `!` too or what? – Işık Kaplan May 24 '19 at 11:39
it's the contrary: i want to match only good email chars, and *even though* I've excluded "by hand" the `!` and the `?` I think this is not a good solution. The idea would be: "you keep emails through a good regexp *or* `@xxx` too" – Olivier Pons May 24 '19 at 11:51
It is hard to re-write the regex every time you want to add a new qualifier. Instead you should've started with this, `I want emails, and emails without the part before @ symbol` Anyway, give this `[\w.+-]*@[\w.+-]*` a shot – Işık Kaplan May 24 '19 at 11:57
I've checked your answer it's good I check it as valid, and I've posted mine as well. Have a good day! – Olivier Pons May 24 '19 at 13:07

score 0 · Accepted Answer · answered May 24 '19 at 13:07

My own solution based on different email parsing + simple "@[:alphanum:]+" parsing is:

USERNAME_OR_EMAIL_REGEX = re.compile(
    r"@[a-zA-Z0-9-]+"  # simple username
    r"|"
    r"[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+"  # email 
    r"@"  # following: domain name:
    r"[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?"
    r"(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)")

Matching alphanumeric words, mentions or emails with Python regex

2 Answers2