How to find a string that contains a given substring in a list

Question

I'm curious to know the most "pythonic" way to check if there is an item in a list of strings that contains a given substring.

For example, say we have a list of email addresses:

['[email protected]', '[email protected]', '[email protected]']

and we need to send an email to most of the emails in this list, but not all of them. What is the simplest (read: most "pythonic") way to check for a list element that contains the substring, say, 'dontemailme.org' and then remove it from the list?

I'm mainly concerned with determining whether an item in the list contains the substring, ideally which item in particular, so that I can make corresponding adjustments to the list.

I come from a C++ background so my initial thought is to use a for loop with an if statement to check but I am often surprised at the flexibility of Python.

You describe 2 different problems to solve. Are you trying to determine if any item in the list contains the substring, e.g. return True in the example you gave, or just get all of the items that don't contain the substring? — G. Anderson
– G. Anderson, Commented Apr 23, 2020 at 20:25
@DeepSpace yes, but that's why I asked for clarification (albeit poorly) of whether the question in the title need to be part of the output as well "check if a string that contains a given substring is present in list" — G. Anderson
– G. Anderson, Commented Apr 23, 2020 at 20:31
@G.Anderson sorry for lack of clarity. The bit about removing the list item just applies to my situation. I'm mainly concerned with constructing a boolean statement that returns whether an item in the list contains the substring, ideally which item. Hopefully that helps — McFizz
– McFizz, Commented Apr 23, 2020 at 20:36
Does this answer your question? How exactly does the python any() function work? — G. Anderson
– G. Anderson, Commented Apr 23, 2020 at 20:41

Gabio · Accepted Answer · 2020-04-23 20:23:15Z

1

You can use list comprehension:

emails = ['[email protected]', '[email protected]', '[email protected]']
output_list = [email for email in emails if 'dontemailme.org' not in email]

print(output_list) # output: ['[email protected]', '[email protected]']

answered Apr 23, 2020 at 20:23

Gabio

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DeepSpace · Accepted Answer · 2020-04-23 20:24:32Z

1

filter is one way:

filtered = filter(lambda email: 'dontemailme.org' not in email, emails)

answered Apr 23, 2020 at 20:24

DeepSpace

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4 Comments

9769953 Over a year ago

With the caveat that while the input is a list, the output is not.

DeepSpace Over a year ago

@00 which is a benefit since no new (probably needless) list is created. OP will probably iterate over these any, so for email in filtered will work just as well. Any kind of iteration will work actually

9769953 Over a year ago

I know that, but for a beginner, just printing filtered may actually be confusing.

McFizz Over a year ago

This is a very interesting approach!

9769953 · Accepted Answer · 2020-04-23 20:23:05Z

0

I would use a list comprehension:

emails = ['[email protected]', '[email protected]', '[email protected]']    
filtered_emails = [email for email in emails if "dontemailme.org" not in email]

answered Apr 23, 2020 at 20:23

9769953

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