How to use a Map instead of Class object to represent data in Scala

Question

My goal is to use a Map (immutable) instead of class to represent my data in Scala. I'm simply transforming the data from one source file into another format and using a Map seems reasonable rather modeling a class to represent my data.

Example:

I have a list of lists for my raw data.

val x = List(List("a","b","c"), List("x","y","z")) // the values, order matters
val y = List("field1","field2","field3") // the keys, order matters

I want to apply the schema to the raw data and create a List of Maps. Order wont matter with Map.

val z = List(Map("field1" -> "a", "field2" -> "b", "field3" -> "c"), List("field1" -> "x", "field2" -> "y", "field3" -> "z"))

I have tried zip but thats not what i want

val z = x zip(y) toMap
  z: scala.collection.immutable.Map[List[String],String] = Map(List(a, b, c) -> field1, List(x, y, z) -> field2)

I keep getting stuck on how I would map over x with y and return a Map. Some direction would be greatly appreciated.

EDITED: This approach was inspired by this talk by Rich Hickey.

cmbaxter · Accepted Answer · 2015-09-01 17:21:41Z

7

I think you are on the right track with zip, you just need to be applying it to each item in x via map instead of applying it one time to x itself. This is one solution, I'm sure there are others:

x.map(xs => y.zip(xs).toMap)

answered Sep 1, 2015 at 17:21

cmbaxter

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1 Comment

rburg Over a year ago

thanks this works, I'm still learning scala so I think I was missing something when I tried the map.

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