From: Glenn Jackman <glennj@...>
Date: 2009-08-28T20:20:06+09:00
Subject: Re: data sctructure

At 2009-08-28 06:16AM, "Juliano ??" wrote:
>  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:

Referencing a hash element that doesn't exist returns nil, so you might
be looking for the ||= operator:

    a ||= b  # if a is false or nil, then set a=b, else return value of a


>    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


    def preprocess(lines)
      d = {}
      lines.each do |line|
        c,s,fc,fl = line.split("\t")
        d[c]        ||= {}
        d[c][s]     ||= {}
        d[c][s][fc] ||= []
        d[c][s][fc] << fl
      end
      d
    end


-- 
Glenn Jackman
    Write a wise saying and your name will live forever. -- Anonymous