From: Robert Klemme <shortcutter@...>
Date: 2007-08-20T06:20:03+09:00
Subject: Re: Detecting duplicates in an array, anything in the standard library   ?

On 19.08.2007 23:15, Robert Klemme wrote:
> 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.

Did I say it's too late?  Man, I should've worn my glasses...

> 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. :-)

Cheers

	robert