dictionary - Elixir获得的值在 map 中不为空

Question

给定这样的 map :
mapOne = %{"dog" => "foo", "cat" => "", "name" => "generic","fizz" => "", }
您将如何只获取列表中为空的值的键？["cat", "fizz"]
似乎Enum.filter返回的是键，值对的列表，而不仅仅是该列表
mapOne |> Enum.filter(fn {k,v} -> if v == "" do k end end)
[{"cat", ""}, {"fizz", ""}]

谢谢!

Answer 1

这种情况下的理解能力很好:

iex(1)> mapOne = %{"dog" => "foo", "cat" => "", "name" => "generic","fizz" => "", }

iex(2)> for {k, v} <- mapOne, v == "", do: k

["cat", "fizz"]