Question

我试图在关注json上调用uniq方法，以便它只返回employee_id上的唯一结果库

# Json array
a ={
  results: [
   {
    employee: {
      name: "A",
      employee_id: "A-00016",
      title: 1
     }
   },{
    employee: {
      name: "A",
      employee_id: "A-00016",
      title: 2
     }
   },{
    employee: {
      name: "C",
      employee_id: "C-00017",
      title: 3
     }
    }
   ]
  }



# Calling uniq on a
a.uniq { |p| p.values_at(:employee_id) }

但是，我只得到这个结果

{
  results: [
   {
    employee: {
      name: "A",
      employee_id: "A-00016",
      title: 1
     }
    }
   ]
  }

而不是我想要的

{
  results: [
   {
    employee: {
      name: "A",
      employee_id: "A-00016",
      title: 1
     },{
    employee: {
      name: "C",
      employee_id: "C-00017",
      title: 3
     }
    }
   ]
  }

我使用正确的方法输出我想要的结果吗？

Answer 1

使用uniq：

input[:results].uniq { |e| e[:employee][:employee_id] }
#⇒ [
#    {:employee=>{:name=>"A", :employee_id=>"A-00016", :title=>"1"}},
#    {:employee=>{:name=>"C", :employee_id=>"C-00017", :title=>"3"}}]

但我相信应该有一些条件适用于选择具有相同id的兄弟姐妹的内容。下面的代码选择具有最大title值的那个：

input[:results].group_by { |e| e[:employee][:employee_id] }
               .map { |_, v| v.max_by { |e| e[:employee][:title].to_i } }
#⇒ [
#    {:employee=>{:name=>"A", :employee_id=>"A-00016", :title=>"2"}},
#    {:employee=>{:name=>"C", :employee_id=>"C-00017", :title=>"3"}}]

Answer 2

以下是一种方法，为了返回修改后的输入hash，我们可以使用uniq!来修改数组a[:results]。我们使用dup复制哈希a以保留它，然后使用tap对重复哈希进行操作。

r = a.dup.tap do |h|
  h[:results].uniq! do |h|
    h[:employee][:employee_id]
  end
end

#=> {:results=>
#    [
#     {:employee=>{:name=>"A", :employee_id=>"A-00016", :title=>1}},
#     {:employee=>{:name=>"C", :employee_id=>"C-00017", :title=>3}}
#    ]
#   }

Answer 3

def selection_criterion(h)
  h[:title].to_i
end

{results: a[:results].group_by {|h| h[:employee][:employee_id]}.
                      values.
                      map {|arr| arr.max_by {|h|  selection_criterion(h[:employee])}}}
   #=> {:results=>
   #     [{:employee=>{:name=>"A", :employee_id=>"A-00016", :title=>2}},
   #      {:employee=>{:name=>"C", :employee_id=>"C-00017", :title=>3}}]}

根据需要定义selection_criterion，并可能将max_by更改为min_by。

步骤如下。

 b = a[:results]
   # => [{:employee=>{:name=>"A", :employee_id=>"A-00016", :title=>1}},
   #     {:employee=>{:name=>"A", :employee_id=>"A-00016", :title=>2}},
   #     {:employee=>{:name=>"C", :employee_id=>"C-00017", :title=>3}}] 
 c = b.group_by { |h| h[:employee][:employee_id] }
   #=> {"A-00016"=>[{:employee=>{:name=>"A", :employee_id=>"A-00016", :title=>1}},
   #                {:employee=>{:name=>"A", :employee_id=>"A-00016", :title=>2}}],
   #    "C-00017"=>[{:employee=>{:name=>"C", :employee_id=>"C-00017", :title=>3}}]}
 d = c.values
   #=> [[{:employee=>{:name=>"A", :employee_id=>"A-00016", :title=>1}},
   #     {:employee=>{:name=>"A", :employee_id=>"A-00016", :title=>2}}],
   #    [{:employee=>{:name=>"C", :employee_id=>"C-00017", :title=>3}}]] 
 e = d.map { |arr| arr.max_by { |h| selection_criterion(h[:employee]) } }
   #=> [{:employee=>{:name=>"A", :employee_id=>"A-00016", :title=>2}},
   #    {:employee=>{:name=>"C", :employee_id=>"C-00017", :title=>3}}]
 { results: e }
   #=> {:results=>
   #     [{:employee=>{:name=>"A", :employee_id=>"A-00016", :title=>2}},
   #      {:employee=>{:name=>"C", :employee_id=>"C-00017", :title=>3}}]}

如何在嵌套数组/哈希上使用ruby uniq

3 个答案: