本文介绍了为什么Elixir的Enum.count不返回数字？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有以下输入内容：
[
[
{"title", "Aaaaaaaaa aaaaaaaaaaa aa aaa oaaaaaaaa"},
{"title", "Aaaaaaa aa aaaa aaa.aa"},
{"title", "Aaaaaaaaaaaa Aaaaaaa, aaa Aaaaaaa"},
{"title", "Aaaa Aaaaaaaa aaaa Aaaaa"},
{"title", "Aaaaaaa Aaaaaaa aaaa Aaaaa"},
{"title", "Aaaaa Aaaaaaa aa Aaaaaa"},
{"title", "Aaaaaaaaa Aaaaa Aaaa Aaaaaaa, Aaa Aaaaaaa"},
{"title",
"Aaaaaaaaa Aaaaaaa Aaaaaa aaaaaaaa Aaaaaaaaaaaaa aaa Aaaaaaaaaa Aaaaaa Aaaaaa Aaaaaaa"},
{"title", "Aaaaaaaaaaaa Aaaaaaa"},
{"title", "Aaaaaaaaa Aaaaa Aaaa Aaaa"}
],
[
{"url",
"http://localhost:3000/aaaaaaaaa-aaaaaaaaaaa-aa-aaa-aaaaaaaaa/"},
{"url", "http://localhost:3000/aaaaaaa-aa-aaaa-aaa-aa/"},
{"url", "http://localhost:3000/aaaaaaaaaaaa-aaaaaaa-aaa-aaaaaaa/"},
{"url", "http://localhost:3000/aaaa-aaaaaaaa-aaaa-aaaaa/"},
{"url", "http://localhost:3000/aaaaaaa-aaaaaaa-aaaa-aaaaa/"},
{"url", "http://localhost:3000/aaaaa-aaaaaaa-aa-aaaaaa/"},
{"url",
"http://localhost:3000/aaaaaaaaa-aaaa-aaaa-aaaaaaa-aaa-aaaaaaa/"},
{"url",
"http://localhost:3000/aaaaaaaaa-aaaaaaa-aaaaaa-aa-aaa-aaaaaaaaaaaaa-aaa-aaaaaaaaaa-aaaaa-aaaaaa-aaaaaaa/"},
{"url", "http://localhost:3000/aaaaaaaaaaaa-aaaaaaa/"},
{"url", "http://localhost:3000/aaaaaaaaa-aaaaa-aaaa-aaaa/"}
]
]
然后启动iex，并将其分配给变量，然后执行计数映射，例如在此iex会话中：
and I start iex, and assign it to a variable, then perform a map of a count, like in this iex session:
Interactive Elixir (1.7.3) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> input = [
...(1)> [
...(1)> {"title", "Aaaaaaaaa aaaaaaaaaaa aa aaa oaaaaaaaa"},
...(1)> {"title", "Aaaaaaa aa aaaa aaa.aa"},
...(1)> {"title", "Aaaaaaaaaaaa Aaaaaaa, aaa Aaaaaaa"},
...(1)> {"title", "Aaaa Aaaaaaaa aaaa Aaaaa"},
...(1)> {"title", "Aaaaaaa Aaaaaaa aaaa Aaaaa"},
...(1)> {"title", "Aaaaa Aaaaaaa aa Aaaaaa"},
...(1)> {"title", "Aaaaaaaaa Aaaaa Aaaa Aaaaaaa, Aaa Aaaaaaa"},
...(1)> {"title",
...(1)> "Aaaaaaaaa Aaaaaaa Aaaaaa aaaaaaaa Aaaaaaaaaaaaa aaa Aaaaaaaaaa Aaaaaa Aaaaaa Aaaaaaa"},
...(1)> {"title", "Aaaaaaaaaaaa Aaaaaaa"},
...(1)> {"title", "Aaaaaaaaa Aaaaa Aaaa Aaaa"}
...(1)> ],
...(1)> [
...(1)> {"url",
...(1)> "http://localhost:3000/aaaaaaaaa-aaaaaaaaaaa-aa-aaa-aaaaaaaaa/"},
...(1)> {"url", "http://localhost:3000/aaaaaaa-aa-aaaa-aaa-aa/"},
...(1)> {"url", "http://localhost:3000/aaaaaaaaaaaa-aaaaaaa-aaa-aaaaaaa/"},
...(1)> {"url", "http://localhost:3000/aaaa-aaaaaaaa-aaaa-aaaaa/"},
...(1)> {"url", "http://localhost:3000/aaaaaaa-aaaaaaa-aaaa-aaaaa/"},
...(1)> {"url", "http://localhost:3000/aaaaa-aaaaaaa-aa-aaaaaa/"},
...(1)> {"url",
...(1)> "http://localhost:3000/aaaaaaaaa-aaaa-aaaa-aaaaaaa-aaa-aaaaaaa/"},
...(1)> {"url",
...(1)> "http://localhost:3000/aaaaaaaaa-aaaaaaa-aaaaaa-aa-aaa-aaaaaaaaaaaaa-aaa-aaaaaaaaaa-aaaaa-aaaaaa-aaaaaaa/"},
...(1)> {"url", "http://localhost:3000/aaaaaaaaaaaa-aaaaaaa/"},
...(1)> {"url", "http://localhost:3000/aaaaaaaaa-aaaaa-aaaa-aaaa/"}
...(1)> ]
...(1)> ]
[
[
{"title", "Aaaaaaaaa aaaaaaaaaaa aa aaa oaaaaaaaa"},
{"title", "Aaaaaaa aa aaaa aaa.aa"},
{"title", "Aaaaaaaaaaaa Aaaaaaa, aaa Aaaaaaa"},
{"title", "Aaaa Aaaaaaaa aaaa Aaaaa"},
{"title", "Aaaaaaa Aaaaaaa aaaa Aaaaa"},
{"title", "Aaaaa Aaaaaaa aa Aaaaaa"},
{"title", "Aaaaaaaaa Aaaaa Aaaa Aaaaaaa, Aaa Aaaaaaa"},
{"title",
"Aaaaaaaaa Aaaaaaa Aaaaaa aaaaaaaa Aaaaaaaaaaaaa aaa Aaaaaaaaaa Aaaaaa Aaaaaa Aaaaaaa"},
{"title", "Aaaaaaaaaaaa Aaaaaaa"},
{"title", "Aaaaaaaaa Aaaaa Aaaa Aaaa"}
],
[
{"url", "http://localhost:3000/aaaaaaaaa-aaaaaaaaaaa-aa-aaa-aaaaaaaaa/"},
{"url", "http://localhost:3000/aaaaaaa-aa-aaaa-aaa-aa/"},
{"url", "http://localhost:3000/aaaaaaaaaaaa-aaaaaaa-aaa-aaaaaaa/"},
{"url", "http://localhost:3000/aaaa-aaaaaaaa-aaaa-aaaaa/"},
{"url", "http://localhost:3000/aaaaaaa-aaaaaaa-aaaa-aaaaa/"},
{"url", "http://localhost:3000/aaaaa-aaaaaaa-aa-aaaaaa/"},
{"url", "http://localhost:3000/aaaaaaaaa-aaaa-aaaa-aaaaaaa-aaa-aaaaaaa/"},
{"url",
"http://localhost:3000/aaaaaaaaa-aaaaaaa-aaaaaa-aa-aaa-aaaaaaaaaaaaa-aaa-aaaaaaaaaa-aaaaa-aaaaaa-aaaaaaa/"},
{"url", "http://localhost:3000/aaaaaaaaaaaa-aaaaaaa/"},
{"url", "http://localhost:3000/aaaaaaaaa-aaaaa-aaaa-aaaa/"}
]
]
iex(2)> input |> Enum.map(fn item -> Enum.count(item) end)
'\n\n'
不清楚上面的iex会话为什么不返回包含[10,10]的列表。我究竟做错了什么？
It's not obvious why the above iex session does not return a list containing [10,10]. What am I doing wrong?
谢谢！
推荐答案
iex使用协议 IO.Inspect ，它将结果视为 charlist ，因此将 \n\n 视为结果。如果使用此行：
iex uses the protocol IO.Inspect, which sees the result as a charlist, hence the \n\n. If you use this line:
iex> input |> Enum.map(fn item -> Enum.count(item) end) |> hd |> to_string |> String.to_integer
您将获得：
iex> 10
显示此列表时遇到的问题与之相同：
it is the same issue that you have when you display this list:
iex> list = [7,8,9]
'\a\b\t'
解决方案：您可以在地图中添加数字（例如0），以强制结果显示为数字列表：
Solution: you can add a number such as 0 into your map, to force the result to appear as list of number:
iex> [0] ++ (input |> Enum.map(fn item -> Enum.count(item) end))
[0,10,10]
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