Select by location using separate features iteratively (pyqgis)

Question

I am looking for a way to run select by location, specific to the features of the 'INTERSECT' layer. I have got bus locations and bus stops and want to figure out when the bus has entered and left individual stops.

Here the orange dots are the bus stops (with varying radius) and the purple ones are the GPS locations of one bus.

With the standard logic, select by location select the GPS locations in all stops and I cannot discriminate when the bus has visited individual stops.

I am using this command for the selection:

processing.run("native:selectbylocation", {'INPUT':Course,'PREDICATE':[0,6],'INTERSECT':Stops,'METHOD':0})

Answer 1

SQL queries are really optimal but I offer you an alternative that will create a layer of gps points for each stop.

My starting layers

# Identification of gps layer
gps = QgsProject.instance().mapLayersByName("gps")[0] 
# Identification of stops layer
stops = QgsProject.instance().mapLayersByName("stops")[0] 

# List : Field with unique identifiers in your stop layer (FID for me)
index = [feature["FID"] for feature in stops.getFeatures()] 

# loop on the list
for i in index:
    # remove selection of gps layer
    gps.removeSelection()
    # remove selection of stops layer  
    stops.removeSelection() 

    # Apply selection 
    stops.selectByExpression('"FID" ='+str(i),QgsVectorLayer.SetSelection) 
    # New layer with my selection
    selection_stops =    stops.materialize(QgsFeatureRequest().setFilterFids(stops.selectedFeatureIds())) 

    # Selectbylocation
    processing.run("native:selectbylocation", {'INPUT':gps,'PREDICATE':[0],'INTERSECT':selection_stops,'METHOD':0}) 

    # New gps layer with the result
    gps_stop = gps.materialize(QgsFeatureRequest().setFilterFids(gps.selectedFeatureIds())) 
    # add the layer to qgis project
    QgsProject.instance().addMapLayer(gps_stop) 
    # rename the layer with the name of stop intersection 
    gps_stop.setName('gps in stop '+str(i)) 

# remove selection of gps layer
gps.removeSelection() 
# remove selection of stops layer 
stops.removeSelection() 

Result

Answer 2

From DB Manager > Virtual Layers > SQL Window, you can run the following query (replace the tables and fields names with real ones) :

SELECT
  bus_stops.id, -- change here the field name id with identifier bus stop field
  MIN(gps.time) AS bus_entered, -- change here the field name time for the gps field with time
  MAX(gps.time) AS bus_left -- same here
FROM
  my_table_bus_stop AS bus_stop, -- change here my_table_bus_stop
  my_table_gps AS gps -- change here my_table_gps
WHERE
  ST_CONTAINS(bus_stop.geometry, gps.geometry)
GROUP BY
  bus_stops.id -- change here too

You can see the result in DB Manager or load it as a Virtual Layer without geometry.