topic Arcade expression to calculate percentage in ArcGIS Online Questions

Arcade expression to calculate percentage

CMcDonald — Wed, 29 Sep 2021 14:16:36 GMT

Hello,

I would like to calculate the percentage of properties that are multiple occupancy.

There are 3 Layers required to do this

1) Multiple Occupancy (Points)

2) Addresses (Points)

3) Zones (Polygons)

I have created 2 expressions in the Zones Layer so that in the pop-up they 'count' the number of properties in both point Layers

Can I create another expression in the Zones Layer that will in effect

Multiple Occupancy Count / Address Count * 100

So that I can get a %

This is my arcade but the % returned although does not error is not the correct figure

//count multiple occupancy properties
var hmo = FeatureSetByName($map, 'Houses in Multiple Occupation HMO')
var countHMO = Count(Intersects(hmo, $feature))
return countHMO
//count addresses
var address = FeatureSetByName($map,"CAG OldAbdn Sample")
var countAddress = Count(Intersects(address,$feature))
return countAddress
//calculate % of multiple occupancy
($feature["countHMO"]/$feature["countAddress"])*100

Thank you 🙂

Re: Arcade expression to calculate percentage

JohannesLindner — Wed, 29 Sep 2021 14:56:49 GMT

You need to remove the return statements. If you return from a function, everything after the statement is not executed.
Arcade expressions don't know of each other. You cant call $feature["countHMO"], because that calls a field that does not exist. You have to calculate countHMO & countAddress again and use them for calculating the percentage.

//count multiple occupancy properties var hmo = FeatureSetByName($map, 'Houses in Multiple Occupation HMO') var countHMO = Count(Intersects(hmo, $feature)) //return countHMO //count addresses var address = FeatureSetByName($map,"CAG OldAbdn Sample") var countAddress = Count(Intersects(address,$feature)) //return countAddress //calculate % of multiple occupancy return (countHMO/countAddress)*100

Re: Arcade expression to calculate percentage

CMcDonald — Wed, 29 Sep 2021 15:37:04 GMT

Thank you @JohannesLindner , that worked perfectly 🙂

I wonder (if I may ask), is it possible/is there any value adding a 'round' statement?

When you test the expression it returns many decimal places

however I can control the appearance through Configure Pop-up > Configure Attributes. I just wondered if you rounded in advance if that would increase performance?

Thanks

Re: Arcade expression to calculate percentage

JohannesLindner — Thu, 30 Sep 2021 06:01:54 GMT

I don't know if it increases the performance (although I guess the effect would be minimal in either way), but you can round:

return Round((countHMO/countAddress)*100, 2)

Re: Arcade expression to calculate percentage

CMcDonald — Thu, 30 Sep 2021 08:19:11 GMT

Cool. Thanks again for your help, much appreciated.