From: raja@... (Raja S.)
Date: 2001-11-30T16:16:25+09:00
Subject: [ruby-talk:27036] Re: Help: factored sorting

Bil Kleb <W.L.Kleb@LaRC.NASA.Gov> writes:

>I have an array of strings,

>a = ["d3", "d33", "d4", "r16", "r33", "d34", "r34"]

>which I'd like to sort by both the numerical suffix and by
>the alphabetic prefix, i.e., I'd like the result,

> ["d3", "d4", "d33", "d34", "r16", "r33", "r34"]

>or, even better would be an array of two prefix-keyed
>sub arrays that I could exploit with the assoc method,
>viz,

> [ ["d", "d3", "d4", "d33", "d34"], ["r", "r16", "r33", "r34"] ]

Hmmm ... again.

I seem to be going thru a think ... post ... re-think ... post cycle
tonight.

Rather than a single sorting phase followed by a grouping phase you could
also have a grouping phase followed by individual sorts:

Extending the 'gather' code posted earlier ...

def sorted_groups( ary )
  hsh = {}
  ary.each do |x|
    primary_key = keys(x).first
    if hsh.has_key?( primary_key )
      hsh[primary_key] << x
    else
      hsh[primary_key] =  [primary_key, x]
    end
  end
  hsh.keys.sort.collect{ |key| hsh[key].sort }
end

enough for now ... g'night

Raja