How does Scala's groupBy identity work?

Question

I was browsing around and found a question about grouping a String by it\'s characters, such as this:

The input:

\"aaabbbccccdd\"
         


        

Answer 1

Take a look at

str.groupBy(identity)

which returns

scala.collection.immutable.Map[Char,String] = Map(b -> bbb, d -> dd, a -> aaa, c -> cccc)

so the key by which the elements are grouped by is the character.