This Ruby script generates a random list of Magic: the Gathering cards, ideally for use in making a random Magic cube, and outputs the card list into a text file (suitable for importing into Magic Online or for use in bulk card shopping). For more information on cube drafting, see cubedrafting.com. You can modify the number of cards generated an…

random-magic-cube.rb

require 'nokogiri'
require 'open-uri'

print "How many cards? "
CARDS_IN_CUBE = gets.strip.to_i
print "What format? "
LEGAL_IN_FORMAT = gets.strip
card_count = 1

# Create or open a text file in the same directory as this file and stores the card names there.
# If the file already exists, it will overwrite it, so you may want to change the name of the file for multiple random cubes.
File.open('random-cube.txt', 'w') do |file|
  while card_count <= CARDS_IN_CUBE
    # Open a random card
    doc = Nokogiri::HTML(open('http://magiccards.info/random.html'))
    
    # Check for the card's format
    legal_formats = doc.css('li.legal').collect{|format| format.content}

    if legal_formats.select{|v| v =~ /#{LEGAL_IN_FORMAT}/}
      # Parse the title and display it
      doc.xpath('//title').each do |link|
        content = link.content.split("(").first
        file.puts "1 " + content
        puts "#" + card_count.to_s + ": " + content
      end
      card_count = card_count + 1
    end
  end
end

Comments, since you asked:

• 2 spaces, no tabs
• you can use a collect on lines 19-21
• while is awkward, I'd change it to re-try fetching the card if it's not legal, rather than repeating the whole loops
• you don't need require rubygems on 1.9, which you should be using
• this is probably overkill for a small script, but yarddoc might be better than random comments
• consider letting you pass the 'constants' as arguments to the script

But hey, if it works, that's what counts! :)

@steveklabnik Thanks! I've updated the script with some of your suggestions. :)