Re: MaxBy and other operations on empty Map.

Er, wait, you _can_ do this with a fold, but not _that_ fold.

I retract my entire statement, and agree with HamsterofDeath that maxOrElse would be nice.

(I also would like the type of fold that would allow a maxBy, but somehow I had forgotten that it's not the default fold since maxBy is not the same as map / max.)

  --Rex

On Thu, Feb 2, 2012 at 1:06 PM, Rex Kerr <ichoran@gmail.com> wrote:

You can do that with a fold.

  val max = map fold (0)((m,x) => m max {something_with_x})

If you are just calling methods, it's even shorter:

  val max = map.fold(0)(_ max _.myMethod)
  val max = map.maxBy(0)(_.myMethod)

It's _barely_ any shorter or clearer to have a dedicated method than to just use a fold.

I think we should just get rid of maxBy, since it cannot have any collection-specific shortcuts due to the mapping, and it isn't safe on empty collections as it is.

  --Rex


I would rather get rid of maxBy, which is unsafe and has no possible shortcuts on any collection, and instead have people use folds.

On Thu, Feb 2, 2012 at 7:28 AM, Edmondo Porcu <edmondo.porcu@gmail.com> wrote:

Dear all,
is there a way to execute a maxBy on Map, which do not throw exception when the map is empty, but returns a default value?
I end up doing:
val max = if (map.isEmpty) 0 else map.maxBy {something}
Don't you think it would be useful to have a method such as
val max = map.maxBy(0){something} 
I think it would be great if this will be included in the collection API...
Best Regards