How to automatically count intersecting geometries by excluding a layer and adding new layers with any layer name

Question

I am using the following expression to count and label the number of geometries of a layer (POINTS1_TO_INCLUDE) that intersect with polygons of another layer (POLYGONS):

to_string(
round(array_length(
overlay_intersects(
array_to_string(
array_filter(
@map_layer_ids,@element not in (@layer_id,'POLYGONS_31860b0b_1cc5_4deb_9016_5fa3bb37ba18'))), $id))))

The result is as follows:

As can be seen in the screenshot, the number of geometries of the POINTS1_TO_INCLUDE layer that intersect with the POLYGONS layer are labeled and the geometries POINTS_TO_EXCLUDE layer are excluded from counting.

The objective is to be able to add new layers with any layer name and keep the expression working. Now the expression stops working when I add a new layer, as you can see in the screenshot:

Any idea how to get the expression to work as shown below:

Answer 1

Use this expression. It calculates the no. of points from all point layers that have include in their name, based on variable @layers that returns the map layers in the current project as a list (see below for further explanations):

array_sum(
    array_foreach(
        @layers ,
        array_length(
            if (
                regexp_match (layer_property(@element, 'name'), 'include'),
                overlay_contains (@element,$id),
                array()
))))

1. @layers returns a list of all layers
2. use array_foreach to loop through all layers
3. get the layer's name layer_property()
4. use regexp_match() to check if the string include is part of the layer's name
5. if this condition is fulfilled, use overlay_contains() to get an array with all features (points) inside the polygon
6. if the condition is not fulfilled, create an empty array: array()
7. calculate the length of the array (how many elements it contains) with array_length()
8. finally, sum up all these lengts using array_sum()