ruby - Sum 2 hashes attributes with the same key

Question

I have 2 hashes, for example:

{'a' => 30, 'b' => 14}
{'a' => 4, 'b' => 23, 'c' => 7}

where a, b and c are objects. How can I sum those hashes' keys to get a new hash like:

{'a' => 34, 'b' => 37, 'c' => 7}

Answer 1

a_hash = {'a' => 30, 'b' => 14}
b_hash = {'a' => 4, 'b' => 23, 'c' => 7}

a_hash.merge(b_hash){ |k, a_value, b_value| a_value + b_value }
=> {"a"=>34, "b"=>37, "c"=>7}

b_hash.merge(a_hash){ |k, b_value, a_value| a_value + b_value }
=> {"a"=>34, "b"=>37, "c"=>7}