How do I compare two hashes?

You can compare hashes directly for equality:

hash1 = {'a' => 1, 'b' => 2}hash2 = {'a' => 1, 'b' => 2}hash3 = {'a' => 1, 'b' => 2, 'c' => 3}hash1 == hash2 # => truehash1 == hash3 # => falsehash1.to_a == hash2.to_a # => truehash1.to_a == hash3.to_a # => false

You can convert the hashes to arrays, then get their difference:

hash3.to_a - hash1.to_a # => [["c", 3]]if (hash3.size > hash1.size)  difference = hash3.to_a - hash1.to_aelse  difference = hash1.to_a - hash3.to_aendHash[*difference.flatten] # => {"c"=>3}

Simplifying further:

Assigning difference via a ternary structure:

  difference = (hash3.size > hash1.size) \                ? hash3.to_a - hash1.to_a \                : hash1.to_a - hash3.to_a=> [["c", 3]]  Hash[*difference.flatten] => {"c"=>3}

Doing it all in one operation and getting rid of the difference variable:

  Hash[*(  (hash3.size > hash1.size)    \      ? hash3.to_a - hash1.to_a \      : hash1.to_a - hash3.to_a  ).flatten] => {"c"=>3}

You can try the hashdiff gem, which allows deep comparison of hashes and arrays in the hash.

The following is an example:

a = {a:{x:2, y:3, z:4}, b:{x:3, z:45}}b = {a:{y:3}, b:{y:3, z:30}}diff = HashDiff.diff(a, b)diff.should == [['-', 'a.x', 2], ['-', 'a.z', 4], ['-', 'b.x', 3], ['~', 'b.z', 45, 30], ['+', 'b.y', 3]]

If you want to get what is the difference between two hashes, you can do this:

h1 = {:a => 20, :b => 10, :c => 44}h2 = {:a => 2, :b => 10, :c => "44"}result = {}h1.each {|k, v| result[k] = h2[k] if h2[k] != v }p result #=> {:a => 2, :c => "44"}