Scala nested map filter

Question

I'm having a nested map which contains both map as well as a combination of List and None value like this

Map(
  test -> 113123, 
  "cat" -> None,
  crm -> List(age, gender, code), 
  myList -> Map(
    test2 -> 321323, 
    test3 -> 11122,
  )
)

But I wanted to filter out non-map values from an above-nested map

expected output:

Map(
  myList -> Map(
    test2 -> 321323,
    test3 -> 11122,
  )
)

Please note that I'm reading above value from JSON and parsing it using JSON parser — JSF Learner
– JSF Learner, Commented Jun 29, 2018 at 12:20

Astrid · Accepted Answer · 2018-06-29 12:49:01Z

2

collect is your friend whenever you want to do something involving filtering a collection in a way that involves restricting to a certain type:

val map : Map[Any, Any] = Map(...)

map.collect {
  case (key, map: Map[_, _]) => (key, map)
}.toMap

edited Jun 29, 2018 at 12:49

answered Jun 29, 2018 at 12:26

Astrid

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5 Comments

JSF Learner Over a year ago

I wanted output like this Map( myList -> Map(test2 -> 321323, test3 -> 11122)) but above code returning List (Key,map(key->value), please help me on this since im very new to scala

JSF Learner Over a year ago

I mean it's returning List(myList , Map(test2 -> 321323, test3 -> 11122)) but i wanted Map(myList -> Map(test2 -> 321323, test3 -> 11122))

Astrid Over a year ago

Ah, whoops - you need to explicitly call .toMap afterwards to get it back to a Map object. I've just edited my answer to add that.

JSF Learner Over a year ago

I'm getting compile time exception for this val finalMappingValues= parsedJson.collect { case (key, map: Map[_, _]) => (key, map) }.toMap

JSF Learner Over a year ago

I wanted to filter out based on key name like - List(age, gender, code) please any on help me on this

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