topic Re: Auto Counter based on Polygon in ArcGIS Field Maps Questions

Auto Counter based on Polygon

JPWillson — Tue, 14 May 2024 16:42:37 GMT

All,

I am attempting to make an Arcade expression that automatically counts up flags placed inside of a polygon. I attempted to grab the counting portion from another user but that aspect of the expression continues to fail. The intersect portion also does not seem to be working correctly. I have attached a sample code. Any suggestions/advice would be greatly appreciated! Thanks in advance.

If (IsEmpty($feature.Flag)) { var numberlist = FeatureSetByName ($map, "Wetland") var topnum = Top(OrderBy(numberlist, 'Flag DESC'), 1) var counter = Number(max(topnum, 'Flag)) var Flag = counter + 1 var polygons = FeatureSetByName($map, "Boundary") var i_polygon = First(Intersects(polygons, $feature)) if(i_polygon == null) {return null} } return i_polygon.Name + Flag

Re: Auto Counter based on Polygon

KerriRasmussen — Wed, 15 May 2024 13:59:37 GMT

Assuming you are adding this calculation to your boundary layer (or the polygon layer where you want to count the flags) try this:

var flags = FeatureSetByName($map, "Flag")

var countFlags = Count(Intersects(flags, $feature))

return countFlags

Re: Auto Counter based on Polygon

JPWillson — Thu, 16 May 2024 13:22:25 GMT

Thank you for your reply. I am attempting to add this calculation to the Flag feature so I can use it to automatically count the flags so numbers are not skipped. As an example, I am doing a wetland delineation in "State Park". I want the field to calculate such that every time I add a point in FieldMaps, the form looks for an intersection with the boundary layer and records that intersection and then adds a number to the end. Something like StatePark 1, StatePark 2, etc. Thank you for your assistance and apologies for the misunderstanding.

Re: Auto Counter based on Polygon

KerriRasmussen — Thu, 16 May 2024 14:23:34 GMT

@JPWillson I haven't done any additional testing yet, but I did just notice the 'Flag' on line 4 in your expression is missing a '.

Re: Auto Counter based on Polygon

KerriRasmussen — Thu, 16 May 2024 19:38:00 GMT

@JPWillson I did some more testing and I came up with this. You will need to make a few changes based on your data, let me know if you have any questions.

//Feature set of your park/polygon boundary var park = FeatureSetByName($map, "Boundaries") //Feature set of your flag layer var flags = FeatureSetByName($map, "Flags") //finding the nearest park/polygon, the park/polygon the point falls in var nearestPark = First(Intersects($feature, park)) //Count of points falling in that polygon var countFlags = Count(Intersects(flags, nearestPark)) //return the park name with a count, and adding one to the count, to account for the new point being added, if no flags, return null If (IsEmpty(countFlags)){ return null }else{ return nearestPark.Name + " " + (countFlags + 1) }

Re: Auto Counter based on Polygon

JPWillson — Sat, 25 May 2024 01:00:18 GMT

Kerri,

Thank you again for assistance. I am trying to use this as an expression for a FieldMap so the wetland features are being created as one is collecting data. I would like the wetland features to be collected as a polygon. As wetland polygons are created, I would like the expression to grab the polygon from the boundaries. Then the count portion would be counting each discrete polygon as they are created. Example: Washington Park 1 would be the first wetland polygon closed in Washington Park.

Re: Auto Counter based on Polygon

KerriRasmussen — Tue, 04 Jun 2024 11:58:35 GMT

//Feature set of your park/polygon boundary

var park = FeatureSetByName($map, "Boundaries")

//Feature set of your wetlands layer

var wetlands = FeatureSetByName($map, "WetlandArea_Test")

//finding the nearest park/polygon, the park/polygon the point falls in

var nearestPark = First(Intersects($feature, park))

//Count of polygons falling in the park polygon

var countWetlands = Count(Intersects(wetlands, nearestPark))

//return the park name with a count, and adding one to the count, to account for the new point being added, if no wetland areas, return null

If (IsEmpty(countWetlands)){

return null

}else{

return nearestPark.Name + " " + (countWetlands + 1)

}