CODEWITHSUNDEEP
pythonlist
rkj
rkj

Reputation: 711

how to filter a value from list in python?

I have list of values , need to filter out values , that doesn't follow a naming convention.

like below list : list = ['a1-23','b1-24','c1-25','c1-x-25']
need to filter : all values that starts with 'c1-' , except 'c1-x-' )

output expected: ['a1-23','b1-24','c1-x-25']

list = ['a1-23','b1-24','c1-25','c1-x-25']
[x for x in list if not x.startswith('c1-')]
['a1-23', 'b1-24']

Upvotes: 0

Views: 412

Answers (2)

ombk
ombk

Reputation: 2111

import re

list1 = ['a1-23','b1-24','c1-25','c1-x-25',"c1-22"]
r = re.compile(r"\bc1-\b\d{2}$") # this regex matches anything with `c1-{2 digits}` exactly
[x for x in list1 if x not in list(filter(r.match,list1))]

# output
['a1-23', 'b1-24', 'c1-x-25']

So what my pattern does is match EXACTLY a word that starts with c1- and ends with two digits only.

Therefore, list(filter(r.match,list1)) will give us all the c1-## and then we do a list comprehension to filter out from list1 all the x's that aren't in the new provided list containing the matches.

x for x in [1,2,3] if x not in [1,2]
#output
[3]

Upvotes: 1

Mureinik
Mureinik

Reputation: 311073

You have the right idea, but you're missing the handing of values that start with c1-x-:

[x for x in list if not x.startswith('c1-') or x.startswith('c1-x-')]

Upvotes: 1

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