Summing values from Bidimensional hash

hashstuff.rb

#see http://nullset2.tumblr.com/post/132761268939/a-quick-recipe-with-hashes

data = { :A => { :D => 100, :E => 200, :F => 300}, :B => { :G => 10, :H => 20, :I => 30 }, :C => { :J => 1, :K => 2, :L => 3 } }
# => {:A=>{:D=>100, :E=>200, :F=>300}, :B=>{:G=>10, :H=>20, :I=>30}, :C=>{:J=>1, :K=>2, :L=>3}}
# data = Hash.new { |k, v| k[v] = Hash.new { |kk, vv| kk[vv] = 0 } } # or you could also initialize that shit like this, then assign stuff to each key-value pair individually

vals = data.map do |k, v| # saving the sums elsewhere temporarily
  v.values.reduce(&:+) #sum the corresponding values to ALL the elements in the "second dimension" of this hash, per first dimension key
end
# => [600, 60, 6]

#then we marry both of these into an array:
data = Hash[data.keys.zip vals]
# => {:A=>600, :B=>60, :C=>6}