Remove string from list if from substring list

Question

I was wondering what's the most pythonic way to:

Having a list of strings and a list of substrings remove the elements of string list that contains any of the substring list.

list_dirs = ('C:\\foo\\bar\\hello.txt', 'C:\\bar\\foo\\.world.txt', 'C:\\foo\\bar\\yellow.txt')

unwanted_files = ('hello.txt', 'yellow.txt)

Desired output:

list_dirs = (C:\\bar\\foo\.world.txt')

I have tried to implement similar questions such as this, but I'm still struggling making the removal and extend that particular implementation to a list.

So far I have done this:

for i in arange(0, len(list_dirs)):
    if 'hello.txt' in list_dirs[i]:
        list_dirs.remove(list_dirs[i])

This works but probably it's not the more cleaner way and more importantly it does not support a list, if I want remove hello.txt or yellow.txt I would have to use a or. Thanks.

It's not safe to modify a collection that you're iterating over. — PM 2Ring
– PM 2Ring, Commented Feb 22, 2015 at 12:06

Sede · Accepted Answer · 2015-02-22 11:40:03Z

2

Using list comprehensions

>>> [l for l in list_dirs if l.split('\\')[-1] not in unwanted_files]
['C:\\bar\\foo\\.world.txt']

Use split to get filename

>>> [l.split('\\')[-1] for l in list_dirs]
['hello.txt', '.world.txt', 'yellow.txt']

edited Feb 22, 2015 at 11:40

answered Feb 22, 2015 at 11:04

Sede

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8 Comments

dudas Over a year ago

Looking a little closer right now. Do this implementation required the correct filename of unwanted files or just a substring? I tested and it seems that required all the correct filename

dudas Over a year ago

Any chance we can modify this to be a substring of the correct filename?

Sede Over a year ago

l.split('\\')[-1] in my answer is the substring of the correct filename. see my edit

PM 2Ring Over a year ago

@dudas: If you need that full substring detection capability, you should say so in the question! To do that requires a different strategy than Michael9's solution: it needs a double loop.

PM 2Ring Over a year ago

@dudas: In that case, maybe you should ask a new question, with appropriate example input.

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kasper Taeymans · Accepted Answer · 2015-02-22 12:01:51Z

1

you also could use a filter function with lambda

print filter(lambda x: x.split('\\')[-1] not in unwanted_files, list_dirs)
#['C:\\bar\\foo\\.world.txt']

or if you don't mind to import os (imo this is cleaner then splitting the string)

print filter(lambda x: os.path.basename(x) not in unwanted_files, list_dirs)

In a list comprehension it would look like this

[l for l in list_dirs if os.path.basename(l) not in unwanted_files]

edited Feb 22, 2015 at 12:01

answered Feb 22, 2015 at 11:56

kasper Taeymans

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