Optional elements in a collection depending on condition with no additional filtering in scala -

i'm trying find best way conditionally add element collection. let me try explain.

let:

val a="1234" val b="1arst" val c=""  

(you can see i'm using colemak layout bet)

i want make map include element if length greater one.

i can go:

map("a" -> a, "b" ->b, "c"->c).filter(_._2.length>0) 

which gives me desired map:

res7: scala.collection.immutable.map[java.lang.string,java.lang.string] =  map(a -> 1234, b -> 1arst) 

i can things like:

map( if(a.length>0) "a"->a else "" -> "" , if(b.length>0) "b"->b else "" -> "" ,  if(c.length>0) "c"->c else "" -> "" )  

but gives me undesired empty string value in map still need filter:

res12: scala.collection.immutable.map[java.lang.string,java.lang.string] = map(a -> 1234, b -> 1arst, "" -> "") 

so thinking of using right associative operators against nil doesn't work end empty list item in list.

scala> "test" -> "test" :: nil :: "test"->"test" :: nil res1: list[product serializable] = list((test,test), list(), (test,test))

is there more efficient way done without filtering on elements second time remove 0 length items?