如何對散列進行分組？

Question

我得到了一個哈希（見下文），我需要組，但我不知道如何去做。 我將在iOS中使用此數組作爲表格部分（Rubymotion）。

散列看起來是這樣的，我想按職業：

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

我需要它看起來像這樣：

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

更新

這將是非常好，如果我能得到這個結構：

{ 
    "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

請執行以下使用Enumerable#group_by：

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"] } 

輸出：（如@mdesantis提到

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

更新，你的預期輸出是不正確的，所以我沒有改變結構到有意義的東西。

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 

輸出

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