From: Toby Rodwell <trodwell@...>
Date: 2010-05-14T22:03:21+09:00
Subject: Re: Comparing elements within an array

Robert Dober wrote:
Many thanks for this, and you ahve exactly described what I am wanting 
to do.  Unfortunately it is throwing up 'undefined method `tap' for 
nil:NilClass (NoMethodError)'.  I tried figuring this out for myself but 
no joy :(  Any ideas?

> On Fri, May 14, 2010 at 12:47 PM, Toby Rodwell <trodwell@iee.org> wrote:
> 
> ah a #unique_by, I therefore conclude that you want to keep one
> element with the given property.
> 
> module Enumerable
>   def unique_by &blk
>     keys = {}
>     reject{ | ele |
>       key = blk[ele]
>       keys[key].tap{ keys[key]=true }
>     }
>   end
> end
> 
> p [*1..10].unique_by{ |x| x % 3 }
> 
> Could'nt come up with something more concise :(
> HTH
> R.

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