From: Robert Klemme <shortcutter@...>
Date: 2007-08-20T06:20:01+09:00
Subject: Re: Detecting duplicates in an array, anything in the standard library ?

On 19.08.2007 12:38, Thibaut Barr�re wrote:
> Hi!
> 
> Just wondering if there is something simple already built in the std
> library to remove duplicates from an array (or an enumerable). I've
> seen and used various approaches, like:
> 
> module Enumerable
>   def dups
>     inject({}) {|h,v| h[v]=h[v].to_i+1; h}.reject{|k,v| v==1}.keys
>   end
> end
> 
> which will give:
> 
>> %w(a b c c).dups
> => ["c"]

Actually you are not deleting duplicates as far as I can see.  Here's 
another one

irb(main):012:0> a.inject(Hash.new(0)) {|h,x| 
h[x]+=1;h}.inject([]){|h,(k,v)|h<<k if v>1;h}
=> ["c"]

You could even change that to need just one iteration through the 
original array but it's too late and I'm too lazy. :-)

Kind regards

	robert