Can I SUM an Arcade Expression Field?

Question

I'm trying to generate fields that will tell field crews a replacement cost per feature and the current total cost of the replacement program based on the work they are doing.  I was expecting the scenario below to work but it does not. Is it possible to call other Arcade expression in other expressions?

For the individual feature's replacement cost: Expression1= (Length*Width)*[StaticMonetaryAmount]

For the total program replacements cost: Expression2 = SUM($layer,'Expression1')

Matt-Huser · Answer

This was my fear. When I attempt to run the entire sum on its own using the $layer parameter, I'm getting values that are doubled.  Here is my attempt at the two different fields and their expression. When I sum the first field (Individual Features' replacement cost) I don't get the same value as the second field shows. It essentially doubles each time.

###Individual Features Replacement Cost###
Var PatchingAreaInYds = ($feature.WIDTH * $feature.LENGTH)/9
PatchingArea*26

##Summarizing All Features Replacement Cost###
Var ASPHALTLENGTH =sum($layer,'LENGTH')
Var ASPHALTWIDTH =sum($layer,'WIDTH')
Var PATCHINGAREAINYDS =(ASPHALTLENGTH*ASPHALTWIDTH)/9
PATCHINGAREAINYDS*26

Matt-Huser · Answer

Thanks for the screenshots this was helpful for me to explore into.  This appears to be for only hosted data layers.  Also I think this is AGOL's version of Field Calculator which you wouldn't be able to run on a field created using an Arcade Expressions.

jcarlson · Answer

In short, no, it is not possible to reference one expression from another. You'll need to calculate the sum entirely on its own.