将字符串转换为列表列表

Question

Input(String):

[[0_busswvan, 24.0, 2019-09-05 20:15:33],[05f9acb08d7c11e89e8fede614b72917, 20.0, 2019-09-05 14:06:32], [0_h2qbu9h3, 28.0, 2019-09-05 14:01:20],[2_busswvan, 24.0, 2019-09-05 20:15:33],[05f9acb08d7c11e89e8fede614b72917, 25.0, 2019-08-12 14:06:32], [1442qbu9h3, 28.0, 2019-09-05 14:01:20]]

I want to convert this string into a list of lists with type: List[List[String,Double,String]]

What's the best possible way to do it?

So far i've tried:

var a : String = "[[0_busswvan, 24.0, 2019-09-05 20:15:33], [05f9acb08d7c11e89e8fede614b72917, 20.0, 2019-09-05 14:06:32], [0_h2qbu9h3, 28.0, 2019-09-05 14:01:20]]" 
var b : String = "[[2_busswvan, 24.0, 2019-09-05 20:15:33],[05f9acb08d7c11e89e8fede614b72917, 25.0, 2019-08-12 14:06:32], [1442qbu9h3, 28.0, 2019-09-05 14:01:20]]" 
a = a.substring(2,a.length-1).concat(",") 
b = b.substring(1,b.length-2) 
var res = a.concat(b) 
var res1 = res.split("\\] ?, ?\\[").map(List(_):List[Any]).toList

But the problem is its of type: List[List[String]]

Answer 1

Alternatively, to pme's solution, you could try to use the parser combinators module .

First, you'd need to add it as a dependency since additional features were moved to separate modules:

libraryDependencies += "org.scala-lang.modules" %% "scala-parser-combinators" % "1.1.2"

Then you could prepare parser:

import java.time.format.DateTimeFormatter;
import java.time._
import scala.util.parsing.combinator._

val r = "[[0_busswvan, 24.0, 2019-09-05 20:15:33],[05f9acb08d7c11e89e8fede614b72917, 20.0, 2019-09-05 14:06:32], [0_h2qbu9h3, 28.0, 2019-09-05 14:01:20],[2_busswvan, 24.0, 2019-09-05 20:15:33],[05f9acb08d7c11e89e8fede614b72917, 25.0, 2019-08-12 14:06:32], [1442qbu9h3, 28.0, 2019-09-05 14:01:20]]"

object Parser extends RegexParsers {
  val formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")

  def text: Parser[String] = """\w+""".r //parser for text
  def number: Parser[Double] = """\d+(\.\d*)?""".r ^^ { _.toDouble } //parser for numbers
  def datetime: Parser[LocalDateTime] = """\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}""".r ^^ { p => LocalDateTime.from(formatter.parse(p)) } //parser for date
  def glue: Parser[String] = """\w*,\w*""".r //parser for comma separators

  def term  : Parser[List[Any]] = "[" ~ text ~ ", " ~ number ~ ", " ~ datetime ~ "]" ~ opt(glue) ^^ { //parser for matching whole sublist
    case _ ~ text ~ _ ~ number ~ _ ~ datetime ~ _ ~ _ =>  {
      List(text, number, datetime)
    }
  }

  def expr  : Parser[List[List[Any]]] = "[" ~> rep(term) <~ "]" //parser for whole list containing arbitrary number of sublist

  def apply(input: String): List[Any] = parseAll(expr, input) match {
    case Success(result, _) => result
    case failure : NoSuccess => scala.sys.error(failure.msg)
  }
}


println(Parser(r))
//List(List(0_busswvan, 24.0, 2019-09-05T20:15:33), List(05f9acb08d7c11e89e8fede614b72917, 20.0, 2019-09-05T14:06:32), List(0_h2qbu9h3, 28.0, 2019-09-05T14:01:20), List(2_busswvan, 24.0, 2019-09-05T20:15:33), List(05f9acb08d7c11e89e8fede614b72917, 25.0, 2019-08-12T14:06:32), List(1442qbu9h3, 28.0, 2019-09-05T14:01:20))

There's also an issue with your approach, that when you use List to store value for Double, String and LocalDateTime then compiler widens the type of list to List[Any] . You could consider using tuple (String, Double, LocalDateTime) instead. In this case parser becomes:

import java.time.format.DateTimeFormatter;
import java.time._
import scala.util.parsing.combinator._

val r = "[[0_busswvan, 24.0, 2019-09-05 20:15:33],[05f9acb08d7c11e89e8fede614b72917, 20.0, 2019-09-05 14:06:32], [0_h2qbu9h3, 28.0, 2019-09-05 14:01:20],[2_busswvan, 24.0, 2019-09-05 20:15:33],[05f9acb08d7c11e89e8fede614b72917, 25.0, 2019-08-12 14:06:32], [1442qbu9h3, 28.0, 2019-09-05 14:01:20]]"

object Parser extends RegexParsers {
  val formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")

  def text: Parser[String] = """\w+""".r //parser for text
  def number: Parser[Double] = """\d+(\.\d*)?""".r ^^ { _.toDouble } //parser for numbers
  def datetime: Parser[LocalDateTime] = """\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}""".r ^^ { p => LocalDateTime.from(formatter.parse(p)) } //parser for date
  def glue: Parser[String] = """\w*,\w*""".r //parser for comma separators

  def term  : Parser[(String, Double, LocalDateTime)] = "[" ~ text ~ ", " ~ number ~ ", " ~ datetime ~ "]" ~ opt(glue) ^^ { //parser for matching whole sublist
    case _ ~ text ~ _ ~ number ~ _ ~ datetime ~ _ ~ _ =>  {
      (text, number, datetime)
    }
  }

  def expr  : Parser[List[(String, Double, LocalDateTime)]] = "[" ~> rep(term) <~ "]" //parser for whole list containing arbitrary number of sublist

  def apply(input: String): List[Any] = parseAll(expr, input) match {
    case Success(result, _) => result
    case failure : NoSuccess => scala.sys.error(failure.msg)
  }
}


println(Parser(r))
//List((0_busswvan,24.0,2019-09-05T20:15:33), (05f9acb08d7c11e89e8fede614b72917,20.0,2019-09-05T14:06:32), (0_h2qbu9h3,28.0,2019-09-05T14:01:20), (2_busswvan,24.0,2019-09-05T20:15:33), (05f9acb08d7c11e89e8fede614b72917,25.0,2019-08-12T14:06:32), (1442qbu9h3,28.0,2019-09-05T14:01:20))

Answer 2

The only small mistake is that you use map instead of flatMap

This works as expected:

 var res1 = res.split("\\] ?, ?\\[").flatMap(List(_):List[Any]).toList

Here is an answer that explains the difference, if you are interested: https://stackoverflow.com/a/45319928/2750966

Another way is to flatten everything in the end:

var res1 = res.split("\\] ?, ?\\[").map(List(_):List[Any]).toList.flatten