From: "Juliano 준호" <jjunho@...>
Date: 2009-08-28T19:23:59+09:00
Subject: data sctructure

Hello guys.

I've just started using ruby and I come from Python... I'm still
learning to think the Ruby way...
Of course, any beginning is hard, but even so I've been having a lot
of fun learning Ruby.
The problem is that I still don't know much about the tons of methods
and I'm maybe letting something pass through my fingers.

My problem is this:
I have to read a file and set up a data structure of embedded
dictionaries. In Python I can easily do that by means of
"dict.defaultdict()", but I didn't understand how to do that in
Ruby... I finally came up with the following:

  def preprocess(lines)
    d = {}
    lines.each do |line|
      c, s, fc, fl = line.split("\t")
        if !d.has_key? c
          d[c] = {}
        end
        if !d[c].has_key? s
          d[c][s] = {}
        end
        if !d[c][s].has_key? fc
          d[c][s][fc] = []
        end
      d[c][s][fc].push fl
    end
    return d
  end

My question is: Is there an easier way to do this in Ruby as it is in
Python?

Same code in Python...

    def preprocess(lines):
        d = {}
        for line in lines:
            c, s, fc, fl = line
            dc = d.setdefault(c, {})
            ds = dc.setdefault(s, {})
            dfc = ds.setdefault(fc, [])
            lfl = dfc.append(fl)
        return d

Thank you very much! :)