python regex find match in list

Question

I have a list:

chain_views = [u'x|frequency|x:y|||cbase', 
               u'x|frequency|x:y||weights_UK18|cbase', 
               u'x|frequency||y|weights_UK18|c%']

I want to check the condition below against the list above

if el.startswith('x|frequency|') and el.split('|')[4]!='' and el.split('|')[3]=='y':

How can I convert the condition above in regex?

Right now I am checking this in a loop and I think regex would be a better option maybe?

for el in chain.views:

    if el.startswith('x|frequency|') and el.split('|')[4]!='' and el.split('|')[3]=='y':
        weighted_views = True
        break
    else:
        weighted_views = False

return weighted_views

What is the goal of that for cycle? it always returns the weighted_views result of the last list element right now. — Martin Valgur
– Martin Valgur, Commented Dec 18, 2015 at 11:50
Are you confusing continue with break? Continue just does the next iteration, which it would do anyway. Also you could avoid calling el.split('|') twice. I know it's only example code, but still worth noting. — Paul Rooney
– Paul Rooney, Commented Dec 18, 2015 at 11:51

eumiro · Accepted Answer · 2015-12-18 12:38:07Z

1

Since the strings look like a sort of CSV, I would prefer to work with split function and completely avoid regex.

for el in chain_views:
    a0, a1, a2, a3, a4, a5 = el.split('|')  # give better names
    if a0 == 'x' and a1 == 'frequency' and a3 == 'y' and a4:
        return True
return False

answered Dec 18, 2015 at 12:38

eumiro

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Jose Enrique Marquez · Accepted Answer · 2015-12-18 14:14:34Z

1

if regular expressions certainly make life easier

I hope this works for you

import re

x = [

u'x|frequency|x:y|||cbase',
u'x|frequency|x:y||weights_UK18|cbase',
u'x|frequency||y|weights_UK18|c%'

]

t = "-".join(x)+'-'

x = re.findall(r'((?:x\|\w+\|(?:x:y)?\|)(?!\|)[^-]*)+', t)

where x is your new list already filtered

answered Dec 18, 2015 at 14:14

Jose Enrique Marquez

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