Question

I am trying to write a regex to catch email Ids . Testing since quite a few hours using regexpal.com . On the site, its able to catch all the email Ids. WHen I am substituting the same regex in Python and doing re.findall(pattern,line), it is not able to catch it.

Regex :

[a-zA-Z0-9-_]+[(.)?a-zA-Z0-9-_]*\s*(@|at)\s*[a-zA-Z0-9-_]+\s*(.|dot)\s*[a-zA-Z0-9-_]*\s*(.|dot)\s*e(\-)?d(\-)?u(\-)?(.,)?

Example :

Line =    <TR> <TD><B>E-Mail: </B> <TD><A HREF=MailTo:*[e-mail]*\>*[e-mail]*</A>

(Highlighted correctly on regexpal.com).

With Python :

 for line in f:
    print 'Line = ',line
        matches = re.findall(my_first_pat,line)
    print 'Matches = ',matches

Gives output:

Line =    <TR> <TD><B>E-Mail: </B> <TD><A HREF=MailTo:[e-mail]>[e-mail]</A>

Matches =  [('@', 'd', '.', '', '', '', ''), ('@', 'd', '.', '', '', '', '')]

What is the issue ?

Answer 1

Read the documentation for re.findall:

If one or more groups are present in the pattern, return a list of groups

Your groups only capture the at sign, dot, etc., therefore that’s all that’s returned by re.findall. Either use non-capturing groups, wrap the whole thing in a group, or use re.finditer.

(As noted by @Igor Chubin, your regex is also incorrectly using . instead of \., but this isn’t causing the main problem.)