(Scala) Creating a Map using for yield {}

Question

I was reading about Maps and so I've tried creating one like this:

val myMap = for(i <- 0 to 10) yield {
  i.toString->"Number"
}

Obviously it would not work. What is the proper way to initialize a map using for loops?

Thanks! ^^

duplicate of https://stackoverflow.com/questions/4213992/can-i-use-for-comprehenion-yield-to-create-a-map-in-scala — joel, Jul 03 '18 at 10:18

user3725190 · Answer 1 · 2018-07-03T11:24:10.350

3

Using toMap on some collections with tuple returns scala.collection.immutable.Map where the first value is the key and the second one is the value itself. For the example above you can do the following (and adopt scala style):

(1 to 10).map( _.toString -> "Number").toMap

edited Jul 03 '18 at 11:24

answered Jul 03 '18 at 10:34

user3725190

343
4
14

the keys in the question are String not Int – joel Jul 03 '18 at 11:20
changed it from: (1 to 10).map( _-> "Number").toMap to (1 to 10).map( _.toString -> "Number").toMap – user3725190 Jul 03 '18 at 11:24

score 2 · Accepted Answer · answered Jul 03 '18 at 09:55

2

You just need to call toMap on the result, like this

val myMap = (for(i <- 0 to 10) yield {
  i.toString -> "Number"
}).toMap

answered Jul 03 '18 at 09:55

Tim

26,753
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(Scala) Creating a Map using for yield {}

2 Answers2