From: WATANABE Hirofumi <eban@...>
Date: 2006-10-13T01:25:15+09:00
Subject: Re: Isolating non-unique items in an array

Hi,

Jason Burgett <jasbur@gmail.com> writes:

> 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.

% irb
>> a = ["a", "a", "a", "b", "c", "d", "d"]
=> ["a", "a", "a", "b", "c", "d", "d"]
>> a.select{|i| a.grep(i).size > 1}
=> ["a", "a", "a", "d", "d"]

-- 
eban