Whoops, i got my section wrong. Disregard the last part. On Mon, 17 Jul 2000, Ken Manheimer wrote: > On Tue, 18 Jul 2000, Peter Schneider-Kamp wrote: > > > One important remark: > > What about unzip()? Shouldn't there be the reverse function? > > One example (which I really wrote not so long ago in an ANN context): > > Evan Simpson (a colleague here at digicool, who'd be a good addition > to python-dev) noticed that unzip is unnecessary - zip is its own > inverse. Since this is a worthwhile observation, i'll indulge a bit > and present it in evan's terms - particularly noting a different > packaging that i think is pretty cool, as methods on sequences. > > > From evan@digicool.com Mon Jul 17 20:17:30 2000 > > Date: Mon, 17 Jul 2000 14:36:18 -0400 > > From: Evan Simpson <evan@digicool.com> > > To: Ken Manheimer <klm@digicool.com> > > Subject: Next Braid > > > > How's this: > > > > ([1, 2, 3], ['a', 'b', 'c']).braid() == ((1, 'a'), (2, 'b'), (3, 'c')) > > [[1, 2, 3], ['a', 'b', 'c']].braid() == [(1, 'a'), (2, 'b'), (3, 'c')] > > > > and > > > > [[1,2,3], ['a']].braid(None) == [(1, 'a'), (2, None), (3, None)] > > > > Also, notice that if 's' is a rectangular sequence of sequences, then for > > all 'a' and 'b': > > > > s.braid()[a][b] == s[b][a] by definition, so > > > > s.braid().braid()[a][b] == s.braid()[b][a] == s[a][b] and therefore, > > > > braid is its own inverse, and we don't need unbraid. > > > > Cheers, > > > > Evan @ digicool & 4-am > > I can't do better than that, but i have one further elaboration i'd > like to see. If the subject sequence already contains some elements, > the result sequence is a copy of the originals with the new braided, > whoops zipped elements appended - this way, braids can be cumulative. > > >>> [(1, 3), (2, 4)].braid(('a', 'b'), ('x', 'y')) > [(1, 3, 'a', 'x'), (2, 4, 'b', 'y')] > > Anyway, we don't need an unzip/unbraid. ! > > Ken > klm@digicool.com > > > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > http://www.python.org/mailman/listinfo/python-dev >
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