scala - 使用 spark 读取 CSV 时，相当于 ^G 的分隔符是什么？

Question

所以，我真的需要帮助做一件愚蠢的事情，但显然我自己无法做到。

我在具有这种格式的文件中有一组行(在 OSX 上使用 less 读取):

XXXXXXXX^GT^XXXXXXXX^G\N^G0^GDL^G\N^G2018-09-14 13:57:00.0^G2018-09-16 00:00:00.0^GCompleted^G\N^G\N^G1^G2018-09-16 21:41:02.267^G1^G2018-09-16 21:41:02.267^GXXXXXXX^G\N
YYYYYYYY^GS^XXXXXXXX^G\N^G0^GDL^G\N^G2018-08-29 00:00:00.0^G2018-08-29 23:00:00.0^GCompleted^G\N^G\N^G1^G2018-09-16 21:41:03.797^G1^G2018-09-16 21:41:03.81^GXXXXXXX^G\N

所以分隔符是 BEL分隔符，我正在以这种方式加载 CSV:

val df = sqlContext.read.format("csv")
  .option("header", "false")
  .option("inferSchema", "true")
  .option("delimiter", "\u2407")
  .option("nullValue", "\\N")
  .load("part0000")

但是当我阅读它时，它只是通过这种方式将行读取为一列:

XXXXXXXXCXXXXXXXX\N0DL\N2018-09-15 00:00:00.02018-09-16 00:00:00.0Completed\N\N12018-09-16 21:41:03.25712018-09-16 21:41:03.263XXXXXXXX\N
XXXXXXXXSXXXXXXXX\N0DL\N2018-09-15 00:00:00.02018-09-15 23:00:00.0Completed\N\N12018-09-16 21:41:03.3712018-09-16 21:41:03.373XXXXXXXX\N

好像有 unkown character (你什么也看不到，只是因为我在 stackoverflow 上格式化了它)代替 ^G .

更新:
这可能是scala对spark的限制吗？
如果我以这种方式使用 Scala 运行代码:

val df = sqlContext.read.format("csv")
  .option("header", "false")
  .option("inferSchema", "true")
  .option("delimiter", "\\a")
  .option("nullValue", "\\N")
  .load("part-m-00000")

display(df)

我长了个大肥

java.lang.IllegalArgumentException: Unsupported special character for delimiter: \a

而如果我用 python 运行:

df = sqlContext.read.format('csv').options(header='false', inferSchema='true', delimiter = "\a", nullValue = '\\N').load('part-m-00000')

display(df)

一切安好!

Answer 1

这些版本在 spark-scala 中看起来有限制，这是代码中支持的 csv 分隔符，

apache/spark/sql/catalyst/csv/CSVOptions.scala

val delimiter = CSVExprUtils.toChar(
    parameters.getOrElse("sep", parameters.getOrElse("delimiter", ",")))

--- CSVExprUtils.toChar
apache/spark/sql/catalyst/csv/CSVExprUtils.scala

  def toChar(str: String): Char = {
(str: Seq[Char]) match {
  case Seq() => throw new IllegalArgumentException("Delimiter cannot be empty string")
  case Seq('\\') => throw new IllegalArgumentException("Single backslash is prohibited." +
    " It has special meaning as beginning of an escape sequence." +
    " To get the backslash character, pass a string with two backslashes as the delimiter.")
  case Seq(c) => c
  case Seq('\\', 't') => '\t'
  case Seq('\\', 'r') => '\r'
  case Seq('\\', 'b') => '\b'
  case Seq('\\', 'f') => '\f'
  // In case user changes quote char and uses \" as delimiter in options
  case Seq('\\', '\"') => '\"'
  case Seq('\\', '\'') => '\''
  case Seq('\\', '\\') => '\\'
  case _ if str == """\u0000""" => '\u0000'
  case Seq('\\', _) =>
    throw new IllegalArgumentException(s"Unsupported special character for delimiter: $str")
  case _ =>
    throw new IllegalArgumentException(s"Delimiter cannot be more than one character: $str")
}