如何分组散列？

Question

我有一个散列(见下面)，我需要分组，但我不知道如何做。我将在iOS (Rubymotion)中的表节中使用这个数组。

散列如下所示，我想按行业分组：

[{"firstname" => "John", "lastname" => "Wayne", "profession" => "actor"},{"firstname" => "Oliva", "lastname" => "Newton", "profession" => "actor"},{"firstname" => "Terry", "lastname" => "Gilliam", "profession" => "director"}]

我需要它看起来像这样：

["actor" => [{"firstname" => "John", "lastname" => "Wayne", "profession" => "actor"},{"firstname" => "Oliva", "lastname" => "Newton", "profession" => "actor"}], "director" =>[{"firstname" => "Terry", "lastname" => "Gilliam", "profession" => "director"}]

更新

如果我能得到这个结构，那就太好了：

{
    "profession" => "actor",
    "people" =>
    [
      {"firstname"=>"John", "lastname"=>"Wayne", "profession"=>"actor"},
      {"firstname" => "Oliva", "lastname" => "Newton", "profession" => "actor"}
    ],
"profession" => "director",
    "people" =>
    [
      {"firstname" => "Terry", "lastname" => "Gilliam", "profession" => "director"}
    ]
  }

Answer 1

使用Enumerable#group_by如下所示：

a = [ 
        {"firstname" => "John", "lastname" => "Wayne", "profession" => "actor"},
        {"firstname" => "Oliva", "lastname" => "Newton", "profession" => "actor"},
        {"firstname" => "Terry", "lastname" => "Gilliam", "profession" => "director"}
    ]

a.group_by { |h| h["profession"] }

输出:

{  "actor"=> [
             {"firstname"=>"John", "lastname"=>"Wayne", "profession"=>"actor"}, 
             {"firstname"=>"Oliva", "lastname"=>"Newton", "profession"=>"actor"}
            ], 
    "director"=> [
             {"firstname"=>"Terry", "lastname"=>"Gilliam", "profession"=>"director"}
                 ]
}

update (正如@mdesantis 所提到的，您的预期输出不是正确的，所以我确实将结构更改为有意义的内容。

a = [ 
        {"firstname" => "John", "lastname" => "Wayne", "profession" => "actor"},
        {"firstname" => "Oliva", "lastname" => "Newton", "profession" => "actor"},
        {"firstname" => "Terry", "lastname" => "Gilliam", "profession" => "director"}
    ]

result_hash = a.group_by { |h| h["profession"] }.map do |key,val|
    {"profession" => key, "people" => val}
end

p result_hash

输出

[
    {"profession"=>"actor", 
    "people"=> [ {"firstname"=>"John", "lastname"=>"Wayne", "profession"=>"actor"},
                 {"firstname"=>"Oliva", "lastname"=>"Newton", "profession" =>"actor"}
                ]
    },
    {"profession"=>"director",
    "people"=>[ {"firstname"=>"Terry", "lastname"=>"Gilliam", "profession"=>"director"}
              ]
    }
]