Question

I am working on a program with regexes, I have to filter them but I can’t find out how. I want to match every red,xxxx or xxxx,red expression in my string and put the colors xxxx into a group. Here is my code:

string = "blue,red   red,yellow   blue,yellow   red,green   purple red, ..."
regex = re.compile('(?:red,(?P<redfirst>\w+)|(?P<othercolorfirst>\w+),red)')

Then I write:

for match in regex.finditer(string):
    if match.group('redfirst')!= "None":
        print(match.group("redfirst"))

But I still obtain printing like:

None
yellow
green
None

I dont want the ‘None’ results to appear, I have to skip them in an smart way if possible.
Thanks for help!

EDIT None without quotes doesn’t work either

Answer 1

>>> import re
>>> regex = re.compile('(?:red,(?P<redfirst>\w+)|(?P<othercolorfirst>\w+),red)')

>>> string = "blue,red   red,yellow   blue,yellow   red,green   purple red, ..."

>>> for matches in regex.finditer(string):
...     if matches.group('redfirst'):
...         print matches.group('redfirst')
...
yellow
green
>>>