Create a field that assigns a value depending how many layers it intersects

Question

I'm trying to create a new field in my attribute table that can assign a value to the polygon depending on how many layers of my buffers it intersects.

So i have a base layer called "properties" and other layers from which i have created different buffers "transport" "green areas" "city center"

In the "properties" layer I want to add a new field to the attribute table assigning a different value depending how many layers (buffers) the polygon intersects.

For example:

If the polygons in "properties" intersects or is contained just "transport" = 1

If the polygons in "properties" intersects or is contained "transport" and "green areas" = 2

If the polygons in "properties" intersects or is contained "Transport", "green areas" and "city center" = 3

If the polygons in "properties" does not intersect any buffer= 0

Any idea if this can be done? And if yes how can I do it? im quite new to QGIS and im still exploring and learning how all the expressions work.

Answer 1

Use this expression in the properties layer to calculate the count of intersecting layers.

array_length(
    array:=array_filter(
        -- list of layer names to evaluate if are intersecting "properties layer
        array:=array(
            'transport',
            'green areas',
            'city center'
        ),
        expression:=overlay_intersects(
            layer:=@element
        )
    )
)