> On 30Dec2016 15:17, Deborah Swanson <pyt...@deborahswanson.net> wrote: > >> Ever consider using conjunctions? > >> > >> if len(l1[st]) and not len(l2[st]): > >> #0 is considered a false -- no need to test for "==0" > >> #non-0 is considered true -- no need to test for ">0" > >> #copy l1 to l2 > >> elif not len(l1[st]) and len(l2[st]): > >> #copy l2 to l1 > >> -- > >> Wulfraed Dennis Lee Bieber AF6VN > >> wlfr...@ix.netcom.com HTTP://wlfraed.home.netcom.com/ > > > >That's a neat shortcut, len(a) instead of len(a)!= 0. Thanks! > > Also, for almost every python collection (lists, tuples, sets > etc), python > boolean logic tests __nonzero__, which works off len() by default. > > So: > > if a: > # a is not empty: len(a) > 0 > else: > # a is empty: len(a) == 0 > > I find this far more readable, presuming the reader knows > that "empty" things > test as false. Of course, you need to ensure that any > "collection"-ish classes > you use or write have this property, but the builtin ones do. > > Cheers, > Cameron Simpson <c...@zip.com.au>
Another neat thing to know, and yes, that's much more readable. I've run into trouble testing for empty (tests failed when they shouldn't have), but I can't remember where I've had that problem, and since it happened early in my learning python, chances are pretty good I screwed something else up. Thanks, I'll remember to try using it again and see if I can get it right. -- https://mail.python.org/mailman/listinfo/python-list
