How to merge two maps into one with keys from the first map and merged values?

Question

How can I create a new map from two maps of maps so that the resulting map only includes matches where keys are the same and combines the internal maps.

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Answer 1

I have been playing with something similar to convert a Seq(Map("one" -> 1), Map("two" -> 2)) to Map("one" -> 1, "two" -> 2).

I have been looking at previous answers and thought it was too difficult. After playing a bit I found that this solution works and it easy:

val seqOfMaps = Seq(Map("one" -> 1), Map("two" -> 2))
seqOfMaps: Seq[scala.collection.immutable.Map[String,Int]] = List(Map(one -> 1), Map(two -> 2))

val allInOneMap = seqOfMaps.flatten.toMap
allInOneMap: scala.collection.immutable.Map[String,Int] = Map(one -> 1, two -> 2)

The advantage of this approach is that possible empty maps automatically get filtered out.