From: Tim Pease <tim.pease@...>
Date: 2006-10-13T00:41:42+09:00
Subject: Re: Isolating non-unique items in an array

On 10/12/06, Jason Burgett <jasbur@gmail.com> 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.
>
> --
> Posted via http://www.ruby-forum.com/.
>
>

class Array
  def count( item )
    return 0 unless self.include? item

    c = 0
    self.each {|i| c += 1 if i == item}
    return c
  end
end

ary = %w(a a a b c d d)
new_ary = ary.select {|item| ary.count(item) > 1}

counts = Hash.new {|h,k| h[k] = new_ary.count(k)}


It's not going to be fast, but it should work.

Blessings,
TwP