How do I remove a specific string from some strings in a list?

Question

I've been trying to figure out a more universal fix for my code and having a hard time with it. This is what I have:

lst = ['Thursday, June ##', 'some string', 'another string', 'etc', 'Friday, June ##', 'more strings', 'etc']

I'm trying to remove everything after the comma in the strings that contain commas (which can only be the day of the week strings).

My current fix that works is:

new_lst = [x[:-9] if ',' in x else x for x in lst]

But this won't work for every month since they're not always going to be a 4 letter string ('June'). I've tried splitting at the commas and then removing any string that starts with a space but it wasn't working properly so I'm not sure what I'm doing wrong.

Tim Biegeleisen · Accepted Answer · 2022-05-17 02:57:50Z

3

We can use a list comprehension along with split() here:

lst = ['Thursday, June ##', 'some string', 'another string', 'etc', 'Friday, June ##', 'more strings', 'etc']
output = [x.split(',', 1)[0] for x in lst]
print(output)
# ['Thursday', 'some string', 'another string', 'etc', 'Friday', 'more strings', 'etc']

edited May 17, 2022 at 2:57

answered May 17, 2022 at 2:43

Tim Biegeleisen

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2 Comments

livisaur Over a year ago

THANK YOU! This is perfect, much appreciated. What does the [0] do in the split method here?

BeRT2me Over a year ago

split() returns a list, so the [0] is the first item in that list

Freddy Mcloughlan · Accepted Answer · 2022-05-17 03:37:32Z

0

With regex:

>>> import re
>>> lst = [re.sub(r',.*', '', x) for x in lst]
>>> lst
['Thursday,', 'some string', 'another string', 'etc', 'Friday,', 'more strings', 'etc']

However, this is slower than the split answer

edited May 17, 2022 at 3:37

answered May 17, 2022 at 2:46

Freddy Mcloughlan

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2 Comments

livisaur Over a year ago

Oh, thank you! I'm actually trying to remove the comma, how would I alter it to do so? Not familiar with regex

Freddy Mcloughlan Over a year ago

@bluetortuga, fixed. The second argument of re.sub is the replacement value. It's now nothing, so the comma will be removed

Avinash · Accepted Answer · 2022-05-17 04:34:57Z

0

You can use re.search in the following way:

import re
lst = ['Thursday, June ##', 'some string', 'another string', 'etc', 'Friday, June ##', 'more strings', 'etc']
for i, msg in enumerate(lst):
    match = re.search(",", msg)
    if match != None:
        lst[i] = msg[:match.span()[0]]
print(lst)

Output:

['Thursday', 'some string', 'another string', 'etc', 'Friday', 'more strings', 'etc']

answered May 17, 2022 at 4:34

Avinash

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