Delete strings (support regex) stored in list from a text file

Question

I'm trying to store a set of strings in a form of a list with the capability of supporting regular expressions and delete those strings from a file.

For example:

list = ['enabled','vs-index \d+']

where 'vs-index \d' is expressed as an regex. (it can be .... vs-index 30, vs-index 40 . etc...)

I have a text file:

config.txt

ltm virtual testing { destination 80.80.80.80:https ip-protocol tcp mask 255.255.255.255 pool pool1 profiles { http { } tcp { } } source 0.0.0.0/0 source-address-translation { type automap } translate-address enabled translate-port enabled vs-index 38 }
ltm virtual blah { destination 50.50.50.50:https mask 255.255.255.255 profiles { fastL4 { } } source 0.0.0.0/0 translate-address enabled translate-port enabled vs-index 35 }

Expected output would be:

ltm virtual testing { destination 80.80.80.80:https ip-protocol tcp mask 255.255.255.255 pool pool1 profiles { http { } tcp { } } source 0.0.0.0/0 source-address-translation { type automap } translate-address enabled translate-port }
ltm virtual blah { destination 50.50.50.50:https mask 255.255.255.255 profiles { fastL4 { } } source 0.0.0.0/0 translate-address enabled translate-port }

The replace() function doesn't accept a list but rather a string. Any way possible to support a list and regex?

if you want to remove `vs-index 38`, it should be `vs-index \d+`. Otherwise it will just match `vs-index 3` and leave `8`. — Barmar, Nov 18 '20 at 19:59

Barmar · Answer 1 · 2020-11-18T20:21:15.743

0

Convert your list to a regexp that matches all the elements, and then use re.sub() to delete all the matches.

import re

l = ['enabled','vs-index \d+']
regex = re.compile('|'.join(l)) # 'enabled|vs-index d+'
with open("config.txt") as f:
    contents = f.read()
result = re.sub(regex, '', contents)
print(result)

edited Nov 18 '20 at 20:21

answered Nov 18 '20 at 20:02

Barmar

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I don't understand when you say "convert your list to a regexp that matches all the elements" because my elements can't be completely different, so it's hard to match everything... – superloopnetworks Nov 18 '20 at 20:07
Do you understand what `|` means in a regular expression? `pattern1|pattern2` matches both pattern1 and pattern2. – Barmar Nov 18 '20 at 20:09
That's what I do with the `join()` function. – Barmar Nov 18 '20 at 20:10
Humm.. I'm trying out the code but it's throwing me an error... – superloopnetworks Nov 18 '20 at 20:13
>>> import re >>> l = ['enabled','vs-index \d+'] >>> regex = re.compile(l.join('|')) Traceback (most recent call last): File "", line 1, in AttributeError: 'list' object has no attribute 'join' >>> with open("remove") as f: ... contents = f.read() ... ... >>> result = re.sub(regex, contents, '') Traceback (most recent call last): File "", line 1, in print(result)NameError: name 'regex' is not defined – superloopnetworks Nov 18 '20 at 20:14
I always forget that in Python `join()` is a string method, not a list method. Fixed it. – Barmar Nov 18 '20 at 20:15
No errors now but no output... – superloopnetworks Nov 18 '20 at 20:18
>>> >>> import re >>> >>> l = ['enabled','vs-index \d+'] >>> regex = re.compile('|'.join(l)) # 'enabled|vs-index d+' >>> with open("remove") as f: ... contents = f.read() ... >>> >>> >>> result = re.sub(regex, contents, '') >>> print(result) >>> – superloopnetworks Nov 18 '20 at 20:19
Oops I had the arguments to `re.sub()` in the wrong order. – Barmar Nov 18 '20 at 20:21
Are you able to help fix the order? – superloopnetworks Nov 18 '20 at 20:24
Thank you sir!. works :) – superloopnetworks Nov 18 '20 at 20:35

Delete strings (support regex) stored in list from a text file

1 Answers1