CODEWITHSUNDEEP
scalacsvexport-to-csv
moez skanjii
moez skanjii

Reputation: 67

Map export to CSV file

I have a Map[String,Seq[Any]], and I want to serialize it to a CSV file.

example: 

Map("k1"-> List(1,2,3),"k2"->List ("toto","fofo","popo"))

to 

k1,k2
1,toto
2,fofo
3,popo

any suggestions ??

Upvotes: 1

Views: 549

Answers (2)

jrook
jrook

Reputation: 3519

Something like this can be a start:

val m : Map[String, Seq[Any]] = Map("k1"-> Seq(1,2,3),"k2"->Seq("toto","fofo","popo"))

val file = new File("/path/to/output/file")
val pw = new PrintWriter(new FileWriter(file))

val header = m.keys.toList
val numLines = m(header.head).get.size
pw.println(header.mkString(","))

(0 until numLines).foreach(n => {
  val line = header.map(k => m(k)(n)).mkString(",")
  pw.println(line)
})
pw.close()

EDIT: I had misunderstood the question and the original answer was wrong. For another approach see LuisMiguelMejíaSuárez's link.

Upvotes: 2

nader.h
nader.h

Reputation: 505

To solve this problem, i would define a method like below if I don't have control on the lists sizes :

def zipNestedLists[A](lists: List[List[A]]): List[List[Any]] = lists match {
    case Nil      => Nil
    case Nil :: _ => Nil
    case _        => lists.map(_.head) :: zipNestedLists(lists.map(_.tail))
  }

if I'm sure that all lists have the same size, then in this case i would use transpose :

scala> List(List(a1,a2,a3,a4), List(b1,b2,b3,b4), List(c1,c2,c3,c4)).transpose
List(List(a1,b1,c1),List(a2,b2,c2),List(a3,b3,c3),List(a4,b4,c4))

please see https://www.scala-lang.org/api/current/scala/collection/immutable/List.html#transpose for more infos on transpose.

Then construct the header :

  val header: String = map.keySet.mkString(",")

After that, the body :

 val body = zipNestedLists(map.values.toList)

then output to the file (thanks @jrook)


val file = new File("path") 
val pw = new PrintWriter(new FileWriter(file))
pw.println(header)
body.foreach(v => pw.println(v.mkString(",")))
pw.close()

Please note that the method zipNestedLists will fail for empty lists. Filter non empty lists before calling it.

Upvotes: 2

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