From: daz <dooby@...10.karoo.co.uk>
Date: 2005-11-25T23:22:28+09:00
Subject: Re: Faster way to pick the every other array member?


Damphyr wrote:
> we have [1,2,3,4,5,6,7] and want [2,4,6]
>


( A more general version of Simon's:
     f=true; p a.select{f=!f}    ):

#--------
  ix=-1; p a.select{ (ix+=1)%2==1 }   #-> [2, 4, 6]
#--------

(Not pretty ... not my fault)


I would prefer not having to maintain the index
in these situations.  Something like this would
suit many similar needs:

<pseudo>
  p a.select{ _i_%2==1 }
</>

- where _i_ (or whatever) is the index that Ruby
is using internally.


daz