copy contents of immutable map to new mutable map

Question

Possible Duplicate:
How can I convert immutable.Map to mutable.Map in Scala?

How do I create a new mutable map with the contents of the immutable map in Scala?

So far I have tried:

val m:scala.collection.mutable.Map[Int, Double] = scala.collection.mutable.Map[Int, Double](imm.map({case(key, value) => (key -> value) }))

to no avail.

@TomaszNurkiewicz - Hah, I forgot I answered this one already. — Rex Kerr, Jan 28 '12 at 22:30

score 28 · Answer 1 · answered Jan 28 '12 at 22:19

28

val im = Map(1->1.0, 2->3.0)
val mm = collection.mutable.Map[Int,Double]() ++= im

answered Jan 28 '12 at 22:19

Rex Kerr

4

`++` creates another collection, while `++=` adds to the one you've got. The latter is less wasteful given that the collection is mutable. – Rex Kerr Jan 29 '12 at 11:59

score 10 · Answer 2 · answered Jan 28 '12 at 22:46

10

val immM = Map(1 -> 2)
val mutM = collection.mutable.Map(immM.toSeq: _*)

answered Jan 28 '12 at 22:46

Blaisorblade

2 Answers2