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

h = { 'foo'=>1, 'bar'=>2 }
key_map = { 'foo'=>'foozle', 'bar'=>'barzle' }

h.each_with_object({}) { |(k,v),g| g[key_map[k]]=v }
  #=> {"foozle"=>1, "barzle"=>2}

or

h.reduce({}) { |g,(k,v)| g.merge(key_map[k]=>v) }
  #=> {"foozle"=>1, "barzle"=>2}