Arcade Expression: show 2 variable ranges, hide 3rd

[JohnBranum]

Hello -

I can't see why this expression for a temperature layer won't work.  It's addressing a Field ("$feature.TmaxC") listing temperature attributes in 5-degree increments from -50 degrees to 30 degrees.

var Cold = ($feature.TmaxC < 10)

var Freeze = iif(Cold < 5, "Freezing", "Near Freezing")

return Freeze

My goal is to limit what's shown to freezing polygons surrounded by near-freezing polygons, and hide any temperatures greater than 10(or 9.9) degrees.  What I THINK it's saying is:

"Cold" is only everything in $feature.TmaxC that's below 10 degrees.

"Freeze" is everything in Cold that's less than 5 degrees (so, 0 on down to -50), and we'll call that "Freezing".

What's left (anywhere it's 5 degrees) is called "Near Freezing".

Now show me the two categories of Freeze.

The result in my map is that the entire planet is one category - freezing.

Thanks for any help!

[DavidPike · Accepted solution]

Proper noob on the Arcade language, 

but the When function might be appropriate:

Logical Functions | ArcGIS for Developers 

var temp = $feature.TmaxC
var ranking = When (temp < 5, “Freezing”,
temp >= 5 && temp < 10, “Near Freezing”,
“”)

return ranking

I can't test this myself at the moment, but it might give a good steer even if it needs finessing.

[JohnBranum]

Thank you, David!  New at this, so the simple idea of "when" never entered my mind.

Learning in baby steps.

[KenBuja]

Your first line

var Cold = ($feature.TmaxC < 10)‍

returns a boolean value (true for all temperatures below 10). So when you test that in your second line

var Freeze = iif(Cold < 5, "Freezing", "Near Freezing")‍

it's actually checking whether true (which evaluates as 1) is less than 5, which is true.

This syntax will give you all your different categories:

return when($feature.TmaxC < 5, "Freezing",
     $feature.TmaxC == 5, "Near Freezing",
     $feature.TmaxC < 10, "Cold",
     "Other"
);‍‍‍‍‍

[JohnBranum]

Thanks, Ken.  At first I thought you were suggesting combining mine with yours, which seemed redundant, then I figured out your "when" block was all it really needed.  Since no "other" is required here (and I like having variables), I finally went with this:

var Temp = $feature.TmaxC
var Cold = when(Temp < 5, "Freezing", Temp < 10 , "Near Freezing","")
return Cold