On Tue, 10 May 2005 23:53:43 GMT, Jim Sizelove <[EMAIL PROTECTED]> wrote: >Bengt Richter wrote: [...] >> Maybe (not tested beyond what you see ;-) I had that feeling ... somehow the word "max" was trying to get my attention, but I posted without figuring out why ;-/ > >It is with some trepidation that I write this message; after hanging >around in c.l.p for the better part of a year, I have come to expect >Bengt's messages to be right-on and error-free. Would that 'twere so ;-)
> >However this time... :) >> >>> def mergespans(spans): >> ... start = end = None >> ... for s,e in sorted(spans): >> ... if start is None: start, end = s,e; continue >> ... if s <= end: end = e; continue >> ... yield start, end >> ... start,end = s,e >> ... if start is not None: yield start, end >> ... >> >>> spans = [(0,3), (4,7), (2,5), (9,14), (12,17)] >> >>> list(mergespans(spans)) >> [(0, 7), (9, 17)] > >There can be a problem in mergespans if one span fits inside another: > Good call. I should have thought of it. > >>> spans = [(0,5), (4,7), (2,3), (9,14), (12,17)] > >>> list(mergespans(spans)) > [(0, 3), (4, 7), (9, 17)] > >Here is a revised version (not tested beyond what you see ;-) > >>> def mergespans(spans): > ... start = end = None > ... for s,e in sorted(spans): > ... if start is None: > ... start, end = s,e > ... continue > ... if s <= end: > ... if end < e: > ... end = e > ... continue > ... yield start, end > ... start,end = s,e > ... if start is not None: > ... yield start, end > ... > >>> list(mergespans([(0,5), (4,7), (2,3), (9,14), (12,17)])) > [(0, 7), (9, 17)] > >>> list(mergespans([(0,3), (4,7), (2,5), (9,14), (12,17)])) > [(0, 7), (9, 17)] > >Can anyone find any other errors in this? ;-) > Not off hand. OTOH, I really didn't like the aesthetics of all that crufty logic in my original. Maybe (again, barely tested ;-) >>> def mergespans(spans): ... it = iter(sorted(spans)) ... start, end = it.next() ... for s,e in it: ... if s <= end: ... end = max(end, e) # was what "max" was trying to tell me, I think ... else: ... yield start, end ... start,end = s,e ... yield start, end ... >>> list(mergespans([(0,5), (4,7), (2,3), (9,14), (12,17)])) [(0, 7), (9, 17)] >>> list(mergespans([(0,3), (4,7), (2,5), (9,14), (12,17)])) [(0, 7), (9, 17)] >With humble regards, Me too. UIAM we're all still human here (even my favorite 'bots, I think ;-) Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
