From: SonOfLilit <sonoflilit@...>
Date: 2007-04-29T21:56:51+09:00
Subject: Re: Partitioning with Set.divide

Well, you could first count how many repetitions there are of each
line and then partition the set of pairs [line, count].

e.g.

h = Hash.new {0} # is this how I set a default value?

STDIN.each_line {|l| h[l] += 1}

partitioning = Set.new(h.to_a).divide{|a| a[0][0]}

Aur

On 4/29/07, Peter Szinek <peter@rubyrailways.com> wrote:
> Hello all,
>
> I have been playing with partitioning a set recently and I am stuck with
> an issue. The whole story is here:
>
> http://www.rubyrailways.com/partitioning-sets-in-ruby/
>
> A quick version for those who would not like to read the article:
>
> Consider this input:
>
> a 53 2 3
> b 8 62 1 23
> a 9 0 31
> b 4 45 4 16 7
> b 1 23
> c 3 42 2 31 4 6
> a 1 3 22
> a 7 83 1 23 3
> b 1 14 4 15 16 2
> c 5 16 2 34
>
> the goal is to create a partition based on the character in the first
> column, i.e.:
>
> <Set: <Set: {"a 9 0 31", "a 7 83 1 23 3", "a 53 2 3", "a 1 3 22 "}>,
> <Set: {"b 1 23 ", "b 1 14 4 15 16 2", "b 8 62 1 23", "b 4 45 4 16 7"}>,
> <Set: {"c 5 16 2 34", "c 3 42 2 31 4 6"}>}>
>
> Which is exactly what Set.divide does. However, there is one problem: I
> would like to know if there are duplicate lines. I.e. divide returns the
> same result, no matter that the input is this:
>
> c 5 16 2 34
> c 5 16 2 34
> c 5 16 2 34
>
> or this:
>
> c 5 16 2 34
>
> What I would need is a modified divide which returns also the count of
> the elements in the input set (at least for those elements which are
> more than once in the set). Is this doable or do I have to roll some
> code to do this for me additionally?
>
> Cheers,
> Peter
>
> __
> http://www.rubyrailways.com :: Ruby and Web2.0 blog
> http://scrubyt.org :: Ruby web scraping framework
> http://rubykitchensink.ca/ :: The indexed archive of all things Ruby
>
>