On 01/04/15 05:50, Jim Mooney wrote:
I'm looking at this and can't see how it works, although I understand zipping and unpacking. The docs say it's a Python idiom. Does "idiom" mean it works in a special way so I can't figure it out from basic principles?
No idiom means a common pattern of usage in the community. In this case thats true of zip(), its less true of this case which is somewhat obscure.
It looks to me like the iterator in the list gets doubled, so the zip should make it [(1,1),(2,2),(3,3),... ], not [(1,2),(3,4),...] What am I missing here?
The fact that thew list contains a reference to an iterator so when you multiply by two you get two references to *the same* iterator. So each time the iterator gets accessed it returns the next number in the sequence, not the same number twice.
s = [1,2,3,4,5,6,7,8] list(zip(*[iter(s)]*2)) [(1, 2), (3, 4), (5, 6), (7, 8)]
Personally I'd have used slicing in this example: zip(s[::2],s[1::2]) Is that any clearer? -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.amazon.com/author/alan_gauld Follow my photo-blog on Flickr at: http://www.flickr.com/photos/alangauldphotos _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
