How to change all the keys of a hash by a new set of given keys

Question

How do I change all the keys of a hash by a new set of given keys?

Is there a way to do that elegantly?

Answer 1

Assuming you have a Hash which maps old keys to new keys, you could do something like

hsh.transform_keys(&key_map.method(:[])) 

Answer 2

Ruby 2.5 has Hash#transform_keys! method. Example using a map of keys

h = {a: 1, b: 2, c: 3} key_map = {a: 'A', b: 'B', c: 'C'}  h.transform_keys! {|k| key_map[k]} # => {"A"=>1, "B"=>2, "C"=>3}  

You can also use symbol#toproc shortcut with transform_keys Eg:

h.transform_keys! &:upcase # => {"A"=>1, "B"=>2, "C"=>3}