Question

我有一个以这种方式完成的数组

[{"g"=>1, "f"=>"01"}, {"g"=>2, "f"=>"02"}, {"g"=>2, "f"=>"03"}, {"g"=>3, "f"=>"04"}, {"g"=>4, "f"=>"05"}, {"g"=>4, "f"=>"06"}]

我必须分成具有相同"g"值的组，例如

[{"g"=>1, "f"=>"01"}],
[{"g"=>2, "f"=>"02"}, {"g"=>2, "f"=>"03"}],
[{"g"=>3, "f"=>"04"}],
[{"g"=>4, "f"=>"05"}, {"g"=>4, "f"=>"06"}]

我尝试a.map{|a| a['g']}.uniq找到所有唯一的"g"，然后使用each函数将结果数组应用于select到第一个数组，但产生没有结果。有人知道如何将数组分组？

Answer 1

input = [{"g"=>1, "f"=>"01"}, {"g"=>2, "f"=>"02"}, {"g"=>2, "f"=>"03"}, {"g"=>3, "f"=>"04"}, {"g"=>4, "f"=>"05"}, {"g"=>4, "f"=>"06"}]

grouped = input.group_by { |hash| hash["g"] }
# => {
#      1=>[{"g"=>1, "f"=>"01"}],
#      2=>[{"g"=>2, "f"=>"02"}, {"g"=>2, "f"=>"03"}],
#      3=>[{"g"=>3, "f"=>"04"}],
#      4=>[{"g"=>4, "f"=>"05"}, {"g"=>4, "f"=>"06"}]
#    }

然后，为了获得解决方案，请致电grouped.values

Answer 2

我更喜欢@ Max使用group_by，但希望展示一种效率相似的替代品。两者都产生一个哈希，然后提取它的值。

arr = [{"g"=>1, "f"=>"01"}, {"g"=>2, "f"=>"02"}, {"g"=>2, "f"=>"03"},
       {"g"=>3, "f"=>"04"}, {"g"=>4, "f"=>"05"}, {"g"=>4, "f"=>"06"}]

arr.each_with_object({}) { |f,h| (h[f["g"]] ||= []) << f }.values
   #=> [[{"g"=>1, "f"=>"01"}],
   #    [{"g"=>2, "f"=>"02"}, {"g"=>2, "f"=>"03"}],
   #    [{"g"=>3, "f"=>"04"}], 
   #    [{"g"=>4, "f"=>"05"}, {"g"=>4, "f"=>"06"}]]

具有相同值的哈希哈希数组

2 个答案: