"Peter Hansen" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > Roger L. Cauvin wrote: >> "Michael Spencer" <[EMAIL PROTECTED]> wrote in message >> news:[EMAIL PROTECTED] >> >>>Roger L. Cauvin wrote: >>>>>>"xyz123aaabbab" accept >>>>>>"xyz123aabbaaab" reject >>>>>>"xayz123aaabab" accept >>>>>>"xaaayz123abab" reject >>>>>>"xaaayz123aaabab" accept >>>>>> >>> >>>This passes your tests. I haven't closely followed the thread for other >>>requirements: >>> >>> >>> pattern = ".*?(?<![a+b])aaab" #look for aaab not preceded by any a+b >> >> Very interesting. I think you may have solved the problem. The key >> seems to be the "not preceded by" part. I'm unfamiliar with some of the >> notation. Can you explain what "[a+b]" and the "(?<!" do? > > I think you might need to add a test case involving a pattern of aaaab > prior to another aaab. From what I gather (not reading too closely), you > would want this to be rejected. Is that true? > > xyz123aaaababaaabab
Adding that test would be a good idea. You're right; I would want that string to be rejected, since in that string the first sequence of 'a' directly preceding a 'b' is of length 4 instead of 3. Thanks for the solution! -- Roger L. Cauvin [EMAIL PROTECTED] (omit the "nospam_" part) Cauvin, Inc. Product Management / Market Research http://www.cauvin-inc.com -- http://mail.python.org/mailman/listinfo/python-list
