spliting a list by nth items

Peter Hansen peter at engcorp.com
Thu Sep 23 19:31:31 CEST 2004


Steven Bethard wrote:
> I feel like this has probably been answered before, but I couldn't
> find something quite like it in the archives.  Feel free to point me
> somewhere if you know where this has already been answered.
> 
> I have a list in a particular order that I want to split into two
> lists: the list of every nth item, and the list of remaining items. 
> It's important to maintain the original order in both lists.
> 
> So the first list is simple:
> 
> nth_items = items[::n]
> 
> The second list is what's giving me trouble.  So far, the best I've
> come up with is:
> 
> non_nth_items = list(items)
> del non_nth_items[::n]
> 
> Is this the right way to do this?

There's probably no "right" way.  Your way isn't the way I
would have thought to do it, I think.  But it's brilliant. :-)
(Also simple and clear.)

-Peter



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