Set Operations on Hashes

• Intersection of Hashes

To get the intersection of two hashes, return the shared keys the values of which are equal:

hash1 = { :a => 1, :b => 2 } hash2 = { :b => 2, :c => 3 } hash1.select { |k, v| (hash2.include?(k) && hash2[k] == v) } # => { :b => 2 }

• Union (merge) of hashes:

keys in a hash are unique, if a key occurs in both hashes which are to be merged, the one from the hash that merge is called on is overwritten:

hash1 = { :a => 1, :b => 2 } hash2 = { :b => 4, :c => 3 }

hash1.merge(hash2) # => { :a => 1, :b => 4, :c => 3 } hash2.merge(hash1) # => { :b => 2, :c => 3, :a => 1 }