CODEWITHSUNDEEP
pythonregexlistparsing
Alex
Alex

Reputation: 355

Remove regex elements from list

I use python 2.7. I have data in file 'a':

[email protected];description1
[email protected];description2
myname3@this_is_ok.ok;description3
[email protected];description4
[email protected];description5
[email protected];description7

I read this file like:

with open('a', 'r') as f:
    data = [x.strip() for x in f.readlines()]

i have a list named bad:

bad = ['abc', 'qwe'] # could be more than 20 elements

Now i'm trying to remove all lines with 'abc' and 'qwe' after @ and write the rest to the newfile. So in newfile should be only 2 lines:

myname3@this_is_ok.ok;description3
[email protected];description7

I've been tryin to use regexp (.?)@(.?);(.*) to get groups, but i don't know what to do next.

Advice me, please!

Upvotes: 3

Views: 2325

Answers (4)

Nick
Nick

Reputation: 1869

I have used regular expression to remove lines which contains @abc or @qwe. Not sure if it is the right method 

import re
with open('testFile.txt', 'r') as f:
     data = [x.strip() for x in f.readlines() if re.match(r'.*@([^abc|qwe]+)\..*;.*',x)]

print data

Now the data will have lines which does not have '@abc' and '@qwe'

Or use

data = [x.strip() for x in f.readlines() if re.search(r'.*@(?!abc|qwe)',x)]

Based on astynax 's suggestion...

Upvotes: 0

Joel Cornett
Joel Cornett

Reputation: 24788

Here's a non-regex solution:

bad = set(['abc', 'qwe'])

with open('a', 'r') as f:
    data = [line.strip() for line in f if line.split('@')[1].split('.')[0] in bad]

Upvotes: 3

jamylak
jamylak

Reputation: 133544

import re
bad = ['abc', 'qwe']

with open('a') as f:
    print [line.strip() 
           for line in f
           if not re.search('|'.join(bad), line.partition('@')[2]]

This solution works as long as bad only contains normal characters eg. letters, numbers, underscores but nothing that interferes with the regex expression like 'a|b' as @phihag pointed out.

Upvotes: 2

phihag
phihag

Reputation: 287815

The regexp .? matches either no or one character. You want .*?, which is a lazy match of multiple characters:

import re
bad = ['abc', 'qwe']

filterf = re.compile('(.*?)@(?!' + '|'.join(map(re.escape, bad)) + ')').match
with open('a') as inf, open('newfile', 'w') as outf:
    outf.writelines(filter(filterf, inf))

Upvotes: 0

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