Auto Counter based on Polygon

Question

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

KerriRasmussen · Answer

//Feature set of your park/polygon boundaryvar park = FeatureSetByName($map, "Boundaries")
//Feature set of your wetlands layervar wetlands = FeatureSetByName($map, "WetlandArea_Test")
//finding the nearest park/polygon, the park/polygon the point falls invar nearestPark = First(Intersects($feature, park))
//Count of polygons falling in the park polygonvar 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 nullIf (IsEmpty(countWetlands)){  return null}else{return nearestPark.Name + " " + (countWetlands + 1)}

JPWillson · Answer

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.

KerriRasmussen · Answer

@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)
}