From: Mark Woodward <markonlinux@...>
Date: 2007-12-02T11:50:04+09:00
Subject: Scrabble Stems Ruby Quiz question.

Hi all,

could someone explain the line:
    (STEMS[stem] ||= {})[letter] = 1
in the code below?
This is a solution (Carlos) from the Scrabble Stems Ruby quiz.

---------------------------------------------------------------
DICT = "/usr/share/dict/words"
CUTOFF = ARGV[0].to_i

STEMS = {}

File.open(DICT) do |f|
  f.each do |word|
    word.chomp!
    next if word.length != 7
    word.downcase!
    letters = word.split(//).sort!
    uniques = letters.uniq
    word = letters.join
    uniques.each do |letter|
      stem = word.sub(letter, "")
      (STEMS[stem] ||= {})[letter] = 1
    end
  end
end

result = STEMS.delete_if { |k,v| v.size < CUTOFF }.
  sort_by { |k,v| v.size }.
  reverse!.
  collect! { |k,v| [k, v.size] }

result.each do |stem, combining| puts "#{stem} #{combining}" end
---------------------------------------------------------------


cheers,

-- 
Mark