Question

If I have a hash {:one => [1,2,3,4], :two => [6,7,8]} how can I just make an array where Array[0] = [1,6], [1] = [2,7], [2] = [3,8], [3] = [4,nil]“ ?

Answer 1

With zip:

h = {:one => [1,2,3,4], :two => [6,7,8]}
h[:one].zip h[:two] # => [[1, 6], [2, 7], [3, 8], [4, nil]]

For any number of keys:

h = {:one => [1,2,3,4], :two => [6,7,8], :three => [9,10]}
vals = h.values # => [[1, 2, 3, 4], [6, 7, 8], [9, 10]]
vals[0].zip *vals[1..-1] # => [[1, 6, 9], [2, 7, 10], [3, 8, nil], [4, nil, nil]]

However I don’t believe the order of these is guaranteed (because hashes are unordered). You might want to consider a different approach. (As David points out in the comments, Hashes are actually ordered in Ruby 1.9, so this isn’t a concern.)