topic Re: Expression based symbology with multiple !IsEmpty in ArcGIS Pro Questions

Expression based symbology with multiple !IsEmpty

arthurV — Tue, 04 Oct 2022 09:17:39 GMT

Hi,

I've read lots of forum questions and tips but don't know how to solve my case.

I am using the expression generator to create 2 symbologies. I have a table with 5 fields/

I would like to define 2 groups:

Group A: features with 2 (or more) fields non empty
Goup B: else (features with only one non empty field)

Re: Expression based symbology with multiple !IsEmpty

JohannesLindner — Tue, 04 Oct 2022 09:47:39 GMT

// get an array of the $feature's values var values = [$feature.GewässerID, $feature.BescheidID, $feature.EinzugsgebietID, $feature.KontaktID, $feature.ASVNummer] // get the count of non-empty values var c = 0 for(var i in values) { c += !IsEmpty(values[i]) } // return true if 2 or more values are non-empty return c >= 2

Re: Expression based symbology with multiple !IsEmpty

arthurV — Wed, 05 Oct 2022 06:59:02 GMT

Thank you for this answer. It worked.
Now could you explain me how this part works?

// get the count of non-empty values var c = 0 for(var i in values) { c += !IsEmpty(values[i]) }

Re: Expression based symbology with multiple !IsEmpty

JohannesLindner — Wed, 05 Oct 2022 07:46:25 GMT

IsEmpty returns a boolean value (true or false). ! is the symbol for "not", it reverses the boolean output. !IsEmpty(value) returns true if the value is not empty.

Booleans can be converted to numbers (true = 1, false = 0). Arcade can do that implicitly, without needing the explicit instruction to do so.

So this code declares a variable c and sets its value to 0. Then it goes through the array of values. For each of those values, it adds the numeric equivalent (0 or 1) of "This value is not empty" to c. So if the value is empty, it adds 0, if the value is not empty, it adds 1. It basically counts the non-empty elements in the array.

Re: Expression based symbology with multiple !IsEmpty

arthurV — Fri, 07 Oct 2022 07:34:11 GMT

What a great explanation. Cheers