Count points in polygon (weighted) for multiple attributes in QGIS 3 in one go

Question

Is there a way to count weighted points inside polygons for multiple attributes at one time?

I can count weight points (below) for an individual attribute, which creates a new polygon layer with an updated attribute table. I have ten attributes of the points that I need to aggregate into the polygons, so this would take a long time to do one by one.

I'd considered setting them up as batch processes, but this generates a new layer each time. I'd like to only generate a new layer once.

Answer 1

Mind using SpatiaLite SQL?

With both your layers loaded into the project

• open the <QGIS> | Database | DB Manager...

  • expand Virtual Layers | Project Layers in the left panel

  • open a new SQL Window (2nd button from left, top row)

  • paste and run (Execute)

    SELECT py.<id_field>,
           py.<some_other_field_1>,
           ...,
           py.<some_other_field_n>,
           COUNT(pt.<id_field>) AS cnt,
           SUM(pt.<weight_attribute_1>) AS w1,
           ...,
           SUM(pt.<weight_attribute_10>) AS w10,
           py.geometry
    FROM <polygon_layer_name> AS py
    JOIN <point_layer_name> AS pt
      ON ST_Within(pt.geometry, py.geometry)
    GROUP BY py.<id_field>,
             py.<some_other_field_1>,
             ...,
             py.<some_other_field_n>
    

  • activate Add as new layer...

    • choose new Layer name and Geometry column (-> geometry)

• <Layer_context> | Save features as... to export as e.g. shapefile

This will select all columns (fields) you specify (<some other_field_n>) from the polygon layer (<polygon_layer_name>), plus the summed up values (w1 - w10) for each <weight_attribute_n> and the count of points (cnt) that are within each polygon, into a new polygon layer; of course you can name the new fields as you like (note: for any name having special characters in it, like "my new #field", enclose the name with "").