From: Jamey Cribbs <jcribbs@...>
Date: 2006-10-13T01:22:06+09:00
Subject: Re: Isolating non-unique items in an array

Jason Burgett wrote:
> I'm basically trying to the opposite of .uniq Let's say I have an array:
>
> ["a", "a", "a", "b", "c", "d", "d"]
>
> I would like to boil this down by first tossing the values that only 
> appear once. Which leaves me with:
>
> ["a", "a", "a", "d", "d"]
>
> Then I need to somehow determine that "a" appears 3 times and "d" 
> appears 2 times. Any help would be great. Thanks.
>
>   
Here's what I whipped up:

letters = ['a','a','a','b','c','d','d']
counts = {}

letters.each do |letter|
  count = letters.find_all { |x| x == letter }.size
  counts[letter] = count if count > 1
end

non_unique_letters = letters.find_all { |x| counts.has_key?(x) }

p counts
p non_unique_letters

Jamey

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