How to use case-agnostic-string-matching-condition in a Python list comprehension?

Question

Is there a way to make a list comprehension to search for a string being case insensitive?

What I do now, which is subpar is:


original_list = ['NAME', 'NUMBER', 'name', 'number', 'Name', 'NaMe', 'place']

filtered_list = [x for x in LIST if "NAME" in x or "name" in x]

This example would exclude "Name" and "NaMe" (which I want to be included) for example. The idea is to use a list comprehension and have a short and concise way of doing this.

I would like to do something like this:


case_insensitive_list = [x for x in LIST if 'name'.caseinsensitive() in x]

(it seems after the second OR the list comprehension begins to behave weird.)

I CANNOT use the str.upper() strategy, I need to retain the case of the original list.

I am expecting a simple list comprehension with a case agnostic string matching condition.

My expected outcome:

['NAME', 'name', 'Name', 'NaMe']

Do you have items in `LIST` which are like: `"NAME1"` or `"ornament"`? — quamrana, Jun 20 '23 at 16:05
"I CANNOT use the str.upper() strategy" It's not clear what you mean by this. `str.upper()` doesn't modify anything in-place, have you tried `...if "NAME" in x.upper()]` to see the result? — G. Anderson, Jun 20 '23 at 16:05
@quamrana All kinds. like: 'NAME_OF_THING', 'random_ornament' — Quant1892387, Jun 20 '23 at 16:06
@G.Anderson the .upper() doesnt work but the .lower() seems to be working. I'm testing whats going on — Quant1892387, Jun 20 '23 at 16:10
@navneethc it depends if OP is interested in matching on `"my_name"` or not. — webelo, Jun 20 '23 at 16:14
Please update your question with your actual desired output. — quamrana, Jun 20 '23 at 16:15
@Quant1892387 `in` checks for membership (e.g. in case you're searching for a substring), `==` checks equality. Functionally, it will not make a difference if you're looking only for variations of 'name', but it makes your intent clearer. — navneethc, Jun 20 '23 at 16:18
@quamrana Is there any modifications to my question that would improve it? I do believe this is a question that could help people out there. — Quant1892387, Jun 20 '23 at 18:29
@navneethc Is there any modifications to my question that would improve it? I do believe this is a question that could help people out there. — Quant1892387, Jun 20 '23 at 18:29
@G.Anderson Is there any modifications to my question that would improve it? I do believe this is a question that could help people out there. — Quant1892387, Jun 20 '23 at 18:30
@Quant1892387 What quamrana said. Be as specific as you can be. — navneethc, Jun 20 '23 at 18:41

score 3 · Answer 1 · answered Jun 20 '23 at 16:06

3

I CANNOT use the str.upper() strategy, I need to retain the case of the original list.

The original list is not affected if you do this in the if condition only:

LIST = ['NAME', 'NUMBER', 'name', 'number', 'Name', 'NaMe', 'place']

filtered_list = [x for x in LIST if "name" in x.lower()]


print(filtered_list)
# ['NAME', 'name', 'Name', 'NaMe']


print(LIST)
# ['NAME', 'NUMBER', 'name', 'number', 'Name', 'NaMe', 'place']

answered Jun 20 '23 at 16:06

webelo

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But the OP didn't want "Name" or "NaMe" to be matched. – quamrana Jun 20 '23 at 16:09
When OP says, "this example will exclude" are they referring to the proposed solution, `[x for x in LIST if "NAME" in x or "name" in x]`, which will indeed exclude `"Name"` and `"NaMe"`? – webelo Jun 20 '23 at 16:13
2

I think OP means "my existing code would exclude `Name` and `NaMe`, therefore my existing code is suboptimal". As opposed to "my target solution would exclude them". – slothrop Jun 20 '23 at 16:13
This answers my question. I do want "Name" and "NaMe" to be matched. Thank you – Quant1892387 Jun 20 '23 at 16:16

score 2 · Answer 2 · answered Jun 20 '23 at 16:16

2

Pretty simple, you just need to turn each item in the list to uppercase and check against the uppercase "NAME" list this.

It might also be wise to get in the habit of not calling lists LIST or list.

my_list = ['NAME', 'NUMBER', 'name', 'number', 'Name', 'NaMe', 'place']

filtered_list = [x for x in my_list if "NAME"==x.upper()]

print(filtered_list)
# ['NAME', 'name', 'Name', 'NaMe']

answered Jun 20 '23 at 16:16

Johnny John Boy

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Thank you. Why use if "NAME"==x.upper() instead of "NAME" in x.upper? – Quant1892387 Jun 20 '23 at 16:20
1

In is going to check a sequence so typically is used when you want to know if a value is IN something, be it a list OR a substring within a string. == is absolute, it will only match if the value is equal. Unless you want a positive match on an item in your list like my_list = ['NAME', 'NUMBER', 'name', 'number', 'Name', 'NaMe', 'hidden_name_in_item', 'place'] then I would always use ==. – Johnny John Boy Jun 20 '23 at 17:38

score 1 · Answer 3 · answered Jun 20 '23 at 17:40

1

You could always use the re module.

import re

LIST = ['NAME', 'NUMBER', 'name', 'number', 'Name', 'NaMe', 'place']
filtered_list = [x for x in LIST if re.match("name", x, re.IGNORECASE)]

answered Jun 20 '23 at 17:40

chepner

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This is a good option. re is not always clear and concise but in this case it is quite nice. – Quant1892387 Jun 20 '23 at 18:27

How to use case-agnostic-string-matching-condition in a Python list comprehension?

3 Answers3