How to label a point layer with the percentage of points within another polygon layer?

Question

I would like to find a method using Geometry generator to label a point layer with the percentage of points inside another polygons layer.

I'm working on implementing a solution based on the COUNT and OVERLAY_WITHIN functions, but for the moment I can't get the solution. An approach of my failed expression is this:

count(within($geometry,collect_geometries(overlay_within('POLYGON', $geometry))))*100/num_geometries($geometry)

With this result:

The idea I am looking for is as shown in the screenshot: label point layer in the centroid of each polygon with the percentage of points:

Answer 1

From what you say, it seems like you wanted to start from the points layer. As you want the number of points within the polygon layer, it's easier to place the logic in the polygon layer (also allowing you to use the native label positioning features, centroid by default).

You can use this formula in the polygon layer Label (or as a Virtual Field in the polygon Attribute Table)

to_string(

   round(

         array_length(overlay_intersects('points', $id)) ---number of points in the polygon
         /
         aggregate('points','count',$id) ---number of points in points layer

   ,2)*100

) ||  ' %'

---

If you want this to automatically apply to any new Point layer, you can update the code to be the following :

  to_string(

   round(

         array_length(overlay_intersects(  array_to_string(  array_filter( @map_layer_ids ,@element!=@layer_id)), $id)) ---number of points in the polygon
         /
         aggregate(  array_to_string(  array_filter( @map_layer_ids ,@element!=@layer_id)),'count',$id) ---number of points in points layer

   ,2)*100

) ||  ' %'

with the point layer name replaced by array_to_string( array_filter( @map_layer_ids ,@element!=@layer_id)) which is the only active layer besides the polygon one. If there are other 'static' layers you want to exclude, you can add them to the filter.

Swithching to another point layer, without changing the Style in the polygon layer:

---

If you have static layers that you want to keep active: add them to the layer filter. Set the filter part to:

@element not in (@layer_id, 'any other layer name you need to remove', 'any other layer to remove',...)

`@layer_id' filters the polygon layer, then add a comma separated list of layers you want to keep active.

For instance I added an OtherLayer displayed on the map. Use the @map_layer_ids to identify its id and added it to the filter list

to_string(round(array_length(overlay_intersects( array_to_string( array_filter( @map_layer_ids ,@element not in (@layer_id,'OtherLayer_a9983d8b_9323_4fac_83de_e8e24e78c8a1'))), $id)) /aggregate( array_to_string( array_filter( @map_layer_ids ,@element not in (@layer_id,'OtherLayer_a9983d8b_9323_4fac_83de_e8e24e78c8a1'))),'count',$id) ,1)*100) || ' %'