erlang NimbleCSV： Elixir

63lcw9qa 于 2022-12-08 发布在 Erlang

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我尝试将NimbleCSV库用于个人项目，但遇到一些问题...

NimbleCSV.define(MyParser, separator: ",", escape: "\"")

defmodule Siren do
  def parseCSV do
    IO.puts("Let's parse CSV file!")
    File.stream!("name.csv")
  |> MyParser.parse_stream
  |> Stream.map(fn [name, team, position, height, weight, age] ->
    %{name: name, team: team, position: position, height: String.to_integer(height), weight: String.to_integer(weight), age: String.to_integer(age)}
    end)
  |> Enum.map(&IO.puts(&1))
  end
end

就像你可以看到上面我使用流，但当我启动我的混合任务崩溃：

➜  siren mix siren
Compiling 1 file (.ex)
Let's parse CSV file!
** (NimbleCSV.ParseError) unexpected escape character " in " \"Team\", \"Position\", \"Height(inches)\", \"Weight(lbs)\", \"Age\"\n"
    deps/nimble_csv/lib/nimble_csv.ex:427: MyParser.separator/5
    deps/nimble_csv/lib/nimble_csv.ex:360: anonymous fn/4 in MyParser.parse_stream/2
    (elixir 1.10.3) lib/stream.ex:902: Stream.do_transform_user/6
    (elixir 1.10.3) lib/stream.ex:1609: Enumerable.Stream.do_each/4
    (elixir 1.10.3) lib/enum.ex:3383: Enum.map/2
    (mix 1.10.3) lib/mix/task.ex:330: Mix.Task.run_task/3
    (mix 1.10.3) lib/mix/cli.ex:82: Mix.CLI.run_task/2

这里我的CSV文件：

"Name", "Team", "Position", "Height(inches)", "Weight(lbs)", "Age"
"Adam Donachie", "BAL", "Catcher", 74, 180, 22.99
"Paul Bako", "BAL", "Catcher", 74, 215, 34.69
"Ramon Hernandez", "BAL", "Catcher", 72, 210, 30.78
"Kevin Millar", "BAL", "First Baseman", 72, 210, 35.43
"Chris Gomez", "BAL", "First Baseman", 73, 188, 35.71
"Brian Roberts", "BAL", "Second Baseman", 69, 176, 29.39
"Miguel Tejada", "BAL", "Shortstop", 69, 209, 30.77
"Melvin Mora", "BAL", "Third Baseman", 71, 200, 35.07
"Aubrey Huff", "BAL", "Third Baseman", 76, 231, 30.19
"Adam Stern", "BAL", "Outfielder", 71, 180, 27.05
"Jeff Fiorentino", "BAL", "Outfielder", 73, 188, 23.88
"Freddie Bynum", "BAL", "Outfielder", 73, 180, 26.96
"Nick Markakis", "BAL", "Outfielder", 74, 185, 23.29
"Brandon Fahey", "BAL", "Outfielder", 74, 160, 26.11
"Corey Patterson", "BAL", "Outfielder", 69, 180, 27.55

问题一定是出在我之前定义的转义符上，但是我不明白为什么？什么是转义符？对我来说，是CSV行中每个字符串周围的双引号。

erlang

来源：https://stackoverflow.com/questions/62727985/nimblecsv-elixir

1条答案

按热度按时间

xsuvu9jc1#

CSV* 表示 * 逗号分隔值 *，它是具有自己的RFC4180的格式。不能在任何时候都输入空格。将输入更改为下面所示的格式，一切都将正常工作。问题是 * 逗号 * 后面有空格，或者换句话说，转义字符没有紧跟在分隔符后面。

"Name","Team","Position","Height(inches)","Weight(lbs)","Age"
"Adam Donachie","BAL","Catcher",74,180,22.99
"Paul Bako","BAL","Catcher",74,215,34.69
"Ramon Hernandez","BAL","Catcher",72,210,30.78
"Kevin Millar","BAL","First Baseman",72,210,35.43
"Chris Gomez","BAL","First Baseman",73,188,35.71
"Brian Roberts","BAL","Second Baseman",69,176,29.39
"Miguel Tejada","BAL","Shortstop",69,209,30.77
"Melvin Mora","BAL","Third Baseman",71,200,35.07
"Aubrey Huff","BAL","Third Baseman",76,231,30.19
"Adam Stern","BAL","Outfielder",71,180,27.05
"Jeff Fiorentino","BAL","Outfielder",73,188,23.88
"Freddie Bynum","BAL","Outfielder",73,180,26.96
"Nick Markakis","BAL","Outfielder",74,185,23.29
"Brandon Fahey","BAL","Outfielder",74,160,26.11
"Corey Patterson","BAL","Outfielder",69,180,27.55

NimbleCSV* 附带了一个默认实现NimbleCSV.RFC4180，它正是您所使用的，因此您不需要定义自己的解析器，使用默认的解析器。

defmodule Siren do
  def parseCSV do
    IO.puts("Let's parse CSV file!")

    File.stream!("name.csv")
    |> NimbleCSV.RFC4180.parse_stream()
    |> Stream.map(fn [name, team, position, height, weight, age] ->
      %{name: name, team: team, position: position,
        height: String.to_integer(height),
        weight: String.to_integer(weight),
        age: String.to_float(age) # NOTE float here!
      }
    end)
    |> Enum.to_list()
    |> IO.inspect()
  end
end
#⇒ [
#  %{
#    age: 22.99,
#    height: 74,
#    name: "Adam Donachie",
#    position: "Catcher",
#    team: "BAL",
#    weight: 180
#  },
#  ...
# ]

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erlang NimbleCSV： Elixir

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