Randomize string contents while retaining the flow

gistfile1.rb

def randomize(str)
  vowels = ['a','e','i','o','u']
  consonants = ('a'..'z').to_a - vowels
  digits = ('0'..'9').to_a
  replacements = {}

  [vowels, consonants, digits].each { |set|
    order = set.sort { rand(2) == 0 ? -1 : 1 }
    set.each_with_index { |char,i| replacements[char] = order[i] }
  }

  tokens = str.split(/\b/)
  
  tokens.collect { |token|
    key = token.downcase
    result = key.gsub(/(.)/) { |c| replacements[c] || c }
    (0..result.length-1).to_a.collect { |i| token[i..i] =~ /[A-Z]/ ? result[i..i].upcase : result[i..i].downcase }.join('')
  }.join('')
end

Before:

The NASA Space Shuttle Challenger disaster occurred on January 28, 1986 when Space Shuttle Challenger broke apart 73 seconds into its flight, leading to the deaths of its seven crew members. Disintegration of the entire vehicle began after an O-ring seal in its right solid rocket booster failed at liftoff. The disaster resulted in the formation of the Rogers Commission, a special commission appointed by United States President Ronald Reagan to investigate the accident. The Presidential Commission found that NASA's organizational culture and decision-making processes had been a key contributing factor to the accident. NASA managers had known that contractor Morton Thiokol's design of the solid rocket boosters contained a potentially catastrophic flaw in the O-rings, but they failed to address it properly. They also disregarded warnings from engineers about the dangers of launching posed by the low temperatures of that morning.

After:

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