From: Ayeye Brazov <brazovayeye@...>
Date: 2009-03-02T21:12:24+09:00
Subject: how to group visitors using hours

Hi,

I've got this problem, I have a Visitor class that keep tracks
of visitors. Each visitor has "created_at" field.
I'd like to group them by hours using "created_at"

I came up with this solution, but I'm not very happy about it...

First, I create a list having ["yy-mm-dd hh",visitor.id], with

    list = visitors.map{|i| [i.created_at.strftime("%Y-%m-%d %H"),
i.id]}

Then, I group each visitor depending on the hours using an Hash

   hs= {}
    for l in list
      if hs.has_key?(l.first)
        hs[l.first] << l.second # Use the hour as index, and append the
visitor id
      else
        hs[l.first] = [l.second]
      end
    end

The result is a Hash hs, and I can use it to get the visitors
given a certain hour.

However, I'm sure there's a better way of doing it, especially if
I'd like to group visitors for "months" or "years"

Any suggestions please?!
thanks
b.
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