Question

我是Elxir的新手。

如果我有以下地图

recos = %{"itemScores" => [%{"item" => "i0", "score" => 0.0126078259487225},
%{"item" => "i3", "score" => 0.007569829148848128},
%{"item" => "i4", "score" => 0.007023984270125072},
%{"item" => "i33", "score" => 0.0068045477730524495}]}

（这是地图吧？）

如何生成所有itemScores以生成RecommendationItems列表？

defmodule RecommendedItem do
  defstruct [:item, :score]
end

我认为它会以某种方式为Enum.map（recos [＆＃34; itemScores＆＃34;]，fn->;）发票，但我不确定

Answer 1

感谢@ zaboco的评论指出struct/2无法正常工作，因为你的地图有字符串而不是原子键。

这是在调用Enum.map：

时的方法

Enum.map(recos["itemScores"], fn %{"item" => item, "score" => score} -> %RecommendedItem{item: item, score: score} end)

这次我测试并验证了代码。

Answer 2

此代码应该按您的要求执行：

defmodule RecommendedItem do
  defstruct item: "", score: 0
end

defmodule Demo do

  defp parse_list([]), do: []

  defp parse_list([%{"item" => i, "score" => s} | tail]) do
    [%RecommendedItem{item: i, score: s} | parse_list(tail) ]
  end

  def create_recommend_list(%{"itemScores" => score_list})  do
    parse_list(score_list)
  end

end

# And this is how you'd call it.

recos = %{"itemScores" => [%{"item" => "i0", "score" => 0.0126078259487225},
%{"item" => "i3", "score" => 0.007569829148848128},
%{"item" => "i4", "score" => 0.007023984270125072},
%{"item" => "i33", "score" => 0.0068045477730524495}]}

l = Demo.create_recommend_list(recos)

# l = [%RecommendedItem{item: "i0", score: 0.0126078259487225},
# %RecommendedItem{item: "i3", score: 0.007569829148848128},
# %RecommendedItem{item: "i4", score: 0.007023984270125072},
# %RecommendedItem{item: "i33", score: 0.0068045477730524495}]

我希望有所帮助。虽然我认为我明白你在问什么，但我不认为将每个地图转换成结构就是你想要做的。

如何枚举地图以生成结构列表

2 个答案: