intersect two hashes based on their keys.

gistfile1.rb

class Hash
  def intersect_by_keys(another_hash)
    delete_if {|k, v| !another_hash.has_key?(k) }
  end
end

{a: 'one', b: 'two'}.intersect_by_keys({a: 'three', d: 'four'}) #=> {:a=>"one"}