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How do I convert a Set("a","b","c") to a Map("a"->1,"b"->2,"c"->3)? I think it should work with toMap.
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To convert a list into a map in Scala, we use the toMap method. We must remember that a map contains a pair of values, i.e., key-value pair, whereas a list contains only single values. So we have two ways to do so: Using the zipWithIndex method to add indices as the keys to the list.
Advertisements. map() method is a member of TraversableLike trait, it is used to run a predicate method on each elements of a collection. It returns a new collection.
zipWithIndex is probably what you are looking for. It will take your collection of letters and make a new collection of Tuples, matching value with position in the collection. You have an extra requirement though - it looks like your positions start with 1, rather than 0, so you'll need to transform those Tuples:
Set("a","b","c")
.zipWithIndex //(a,0), (b,1), (c,2)
.map{case(v,i) => (v, i+1)} //increment each of those indexes
.toMap //toMap does work for a collection of Tuples
One extra consideration - Sets don't preserve position. Consider using a structure like List if you want the above position to consistently work.
197
Here is another solution that uses a Stream of all natural numbers beginning from 1 to be zipped with your Set:
scala> Set("a", "b", "c") zip Stream.from(1) toMap
Map((a,1), (b,2), (c,3))
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