在Elixir中将相同键上的两个映射组合在一起

Question

我对Elixir很陌生,只想找到将两张地图组合在一起的最佳方法.更具体:

name_map = %{
  105 => "Jim",
  48 => "Maria",
  62 => "Karen",
  888 => "Foo"
}

job_map = %{
  105 => "Social worker",
  48 => "Programmer",
  62 => "Teacher",
  999 => "Bar"
}

我想要得到

combined_map = %{
  105 => %{"name" => "Jim", "job" => "Social worker"},
  48 => %{"name" => "Maria", "job" => "Programmer"},
  62 => %{"name" => "Karen", "job" => "Teacher"},
  888 => %{job: nil, name: "Foo"},
  999 => %{job: "Bar", name: nil}}
}

在此先感谢您的帮助!

Answer 1

一个简单的解决方案:从两个映射中获取所有键,迭代键,从映射中检索值并构造元组{key, %{name: name, job: job}},然后将元组减少为映射.

name_map = %{
  105 => "Jim",
  48 => "Maria",
  62 => "Karen",
  888 => "Foo"
}

job_map = %{
  105 => "Social worker",
  48 => "Programmer",
  62 => "Teacher",
  999 => "Bar"
}

combined_map = Map.keys(name_map) ++ Map.keys(job_map)
               |> Stream.uniq
               |> Stream.map(&{&1, %{name: name_map[&1], job: job_map[&1]}})
               |> Enum.into(%{})

%{48 => %{job: "Programmer", name: "Maria"},
  62 => %{job: "Teacher", name: "Karen"},
  105 => %{job: "Social worker", name: "Jim"}, 
  888 => %{job: nil, name: "Foo"},
  999 => %{job: "Bar", name: nil}}

Answer 2

假设您在两个地图中都有相同的键，这很容易：

Map.merge(name_map, job_map, fn _k, v1, v2 ->
  %{name: v1, job: v2}
end)
#? %{48 => %{job: "Programmer", name: "Maria"},
#    62 => %{job: "Teacher", name: "Karen"},
#   105 => %{job: "Social worker", name: "Jim"}}

是否要支持没有工作的名称，反之亦然：

Enum.into(Map.keys(name_map) ++ Map.keys(job_map), %{}, fn k ->
  {k, %{name: Map.get(name_map, k), job: Map.get(job_map, k)}}
end)
#? %{48 => %{job: "Programmer", name: "Maria"},
#    62 => %{job: "Teacher", name: "Karen"},
#   105 => %{job: "Social worker", name: "Jim"},
#   888 => %{job: nil, name: "Foo"},
#   999 => %{job: "Bar", name: nil}}