`gis:create-turtles-inside-polygon` fails with `Extension exception: Index 0 out of bounds for length 0`

[EwoutH]

I'm using the gis:create-turtles-inside-polygon function with the GIS Extension of NetLogo 6.3.0. I follow the example listed in the docs, with a few lines of code added to place each agent in the center of that polygon. That also prevents all agents outside my world envelope from being created.

to setup-spots
  ;; For each parking space, determine the centroid, convert to x,y coordinates (list with 2 elements),
  ;; and create a turtle in the center of that polygon 
  foreach gis:feature-list-of parking-dataset [ this-vector-feature ->
    let center gis:centroid-of this-vector-feature
    let loc gis:location-of center
    if  length loc >= 2 [
      gis:create-turtles-inside-polygon this-vector-feature spots 1 [setxy item 0 loc item 1 loc]
    ]
  ]
end

However, it fails with a weird error: Extension exception: Index 0 out of bounds for length 0. I tried about everything, but it just keeps failing. Could it be my data source?

@JamesHovet, since you wrote this function, do you have any idea what's going on? Or @LaCuneta?

Here are my model and data: NetLogo-GIS-test.zip

Model code

extensions [gis]
globals [parking-dataset projection]
breed [spots spot]
spots-own [AMENITY]

to setup
  clear-all
  load
  draw
  setup-spots
end

to load
  set projection "WGS_84_Geographic"
  set parking-dataset gis:load-dataset "export2.geojson"
  gis:set-world-envelope (list 5.671533 5.684606 52.026888 52.019735)
end

to setup-spots
  ;; For each parking space, determine the centroid, convert to x,y coordinates (list with 2 elements),
  ;; and create a turtle in the center of that polygon 
  foreach gis:feature-list-of parking-dataset [ this-vector-feature ->
    let center gis:centroid-of this-vector-feature
    let loc gis:location-of center
    if  length loc >= 2 [
      gis:create-turtles-inside-polygon this-vector-feature spots 1;; [setxy item 0 loc item 1 loc]
    ]
  ]
end

to draw
  gis:set-drawing-color red
  gis:fill parking-dataset 0
end

to clear
  clear-all
end

Full error

Extension exception: Index 0 out of bounds for length 0
error while observer running GIS:CREATE-TURTLES-INSIDE-POLYGON
called by (anonymous command: [ this-vector-feature -> let center gis:centroid-of this-vector-feature let loc gis:location-of center if length loc >= 2 [ gis:create-turtles-inside-polygon this-vector-feature spots 1 ] ])
called by procedure SETUP-SPOTS
called by procedure SETUP
called by Button 'setup'

org.nlogo.nvm.WrappedExtensionException: Extension exception: Index 0 out of bounds for length 0
at org.nlogo.nvm.AnonymousCommand.perform(AnonymousProcedure.scala:212)
at org.nlogo.nvm.AnonymousCommand.perform(AnonymousProcedure.scala:184)
at org.nlogo.prim.etc._foreach.perform(_foreach.scala:38)
at org.nlogo.nvm.Context.stepConcurrent(Context.java:107)
at org.nlogo.nvm.ConcurrentJob.step(ConcurrentJob.scala:65)
at org.nlogo.job.JobThread.runPrimaryJobs(JobThread.scala:133)
at org.nlogo.job.JobThread.$anonfun$run$1(JobThread.scala:68)
at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
at scala.util.control.Exception$Catch.apply(Exception.scala:228)
at org.nlogo.api.Exceptions$.handling(Exceptions.scala:41)
at org.nlogo.job.JobThread.run(JobThread.scala:66)
Caused by: org.nlogo.api.ExtensionException: Index 0 out of bounds for length 0
at com.vividsolutions.jts.geom.GeometryCollection.getGeometryN(GeometryCollection.java:138)
at org.myworldgis.netlogo.VectorFeature.getRandomTriangleWeightedByArea(VectorFeature.java:347)
at org.myworldgis.netlogo.VectorFeature.getRandomPointInsidePolygon(VectorFeature.java:359)
at org.myworldgis.netlogo.CreateTurtlesInsidePolygon$TurtlesInsidePolygon.performInternal(CreateTurtlesInsidePolygon.java:63)
at org.myworldgis.netlogo.CreateTurtlesInsidePolygon$TurtlesInsidePolygonAutomatic.performInternal(CreateTurtlesInsidePolygon.java:83)
at org.myworldgis.netlogo.GISExtension$Command.perform(GISExtension.java:61)
at org.nlogo.prim._extern.perform(_extern.java:36)
at org.nlogo.nvm.Context.runExclusive(Context.java:133)
at org.nlogo.nvm.AnonymousCommand.perform(AnonymousProcedure.scala:206)
... 10 more

NetLogo 6.3.0
main: org.nlogo.app.AppFrame
thread: JobThread
OpenJDK 64-Bit Server VM 17.0.3 (BellSoft; 17.0.3+7-LTS)
operating system: Windows 11 10.0 (amd64 processor)
Scala version 2.12.16
JOGL: (3D View not initialized)
OpenGL Graphics: (3D View not initialized)
model: GIS_test

01:17:21.163 RuntimeErrorEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) AWT-EventQueue-0
01:17:21.147 JobRemovedEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) JobThread
01:17:21.147 OutputEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) AWT-EventQueue-0
01:17:21.139 PeriodicUpdateEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) AWT-EventQueue-0
01:17:21.139 TickStateChangeEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) JobThread
01:17:21.139 OutputEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) AWT-EventQueue-0
01:17:21.139 AddJobEvent (org.nlogo.window.ButtonWidget) AWT-EventQueue-0
01:17:21.089 InputBoxLoseFocusEvent (org.nlogo.window.ButtonWidget) AWT-EventQueue-0
01:17:21.038 PeriodicUpdateEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) AWT-EventQueue-0
01:17:20.823 PeriodicUpdateEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) AWT-EventQueue-0

[JamesHovet]

Looks like there's something in that dataset that is giving gis:create-turtles-inside-polygon a hard time. The good news for you @EwoutH is that since you want the turtles you are creating to be in the center of the polygon, the old fashioned way of creating turtles from polygons (before I created gis:create-turtles-inside-polygon) still works for you! Try this for your setup-spots function:

to setup-spots
  ;; For each parking space, determine the centroid, convert to x,y coordinates (list with 2 elements),
  ;; and create a turtle in the center of that polygon
  foreach gis:feature-list-of parking-dataset [ this-vector-feature ->
    let center gis:centroid-of this-vector-feature
    let loc gis:location-of center

    if length loc >= 2 [
      create-spots 1 [
        setxy item 0 loc item 1 loc
        set AMENITY gis:property-value this-vector-feature "AMENITY"
      ]
    ]
  ]
end

[EwoutH]

Thanks for getting back! It's a bit less scalable when adding other property-values in the future, but in my case I can get it to work.

I generated my dataset using OpenStreetMap data collected on https://overpass-turbo.eu/, using the query:

[bbox:{{bbox}}];

area
  [amenity=parking];
/*added by auto repair*/
(._;>;);
/*end of auto repair*/

out;

In the case anyone wants to debug this.