How can I do this

puzzled.rb

# underpants
data = [
  {a: 1, b: 1, c: 'a'},
  {a: 1, b: 2, c: 'b'},
  {a: 2, b: 2, c: 'c'}
]

# ?
new_data = transform_data(data)

# profit!
new_data[1][1]
# => 'a'
new_data[1][2]
# => 'b'

I only use inject if I'm not modifying anything. If I'm doing any sort of mutation, I use each_with_object. When building state from scratch, mutation is just faster, so I use each_with_object waaaaay more than inject.