Flatten a Map of Option to Map [duplicate]

Question

I have a Map[A, Option[B]], what is the optimal way to make a flatten to get a Map[A, B] ?

I know for a list we can use flatten, but this structure is different

Answer 1

Well, they are not the same, so you will need a way to define what happens if a value is None. I assume you want to ignore those keys, if so, you can collect with a partial function:

map.collect {
  case (k, Some(v)) => k -> v
}

or use a for-comprehension

  for ((k, Some(v)) <- map) yield k -> v