如何比较两个填充哈希的数组并返回第二个不存在的哈希？

Question

假设我有两个充满哈希的数组，

array_a = [{'key' => 'a'}, {'key' => 'b'}, {'key' => 'c'}, {'key' => 'd'}]
array_b = [{'key' => 'a'}, {'key' => 'b'}, {'key' => 'd'}]

如何比较array_a和array_b并返回array_b中未找到的哈希值。

所以比较应该返回：

# => [{'key' => 'c'}]

Answer 1

Array#-可行：

array_a = [{'key' => 'a'}, {'key' => 'b'}, {'key' => 'c'}, {'key' => 'd'}]
array_b = [{'key' => 'a'}, {'key' => 'b'}, {'key' => 'd'}]

array_a - array_b
#=> [{"key"=>"c"}]

方法＆＃34; ...使用hash和eql?方法...＆＃34; 并根据Hash#hash比较元素：

  

具有相同内容的两个哈希将具有相同的哈希码（并将使用eql?进行比较）。