Ruby - Interleaving arrays (via http://stackoverflow.com/questions/3587227/how-to-interleave-arrays-of-different-length-in-ruby)

interleave.rb

# If the source arrays don't have nil in them, you only need to extend the first array with nils, zip will automatically pad the others with nil. This also means you get to use compact to clean the extra entries out which is hopefully more efficient than explicit loops

def interleave(a,*args)
    max_length = args.map(&:size).max
    padding = [nil]*[max_length-a.size, 0].max
    (a+padding).zip(*args).flatten.compact
end

# Here is a slightly more complicated version that works if the arrays do contain nil

def interleave(*args)
    max_length = args.map(&:size).max
    pad = Object.new()
    args = args.map{|a| a.dup.fill(pad,(a.size...max_length))}
    ([pad]*max_length).zip(*args).flatten-[pad]
end