Creating multiple routes with several stops using QGIS

Question

I am trying to find the shortest paths given a number of points with a specific order for each path. Specifically, my point data have the following format:

I used the approved solution given in Routing with several stops using QGIS, and it works perfectly if my data have only 1 route.

How can I modify the proposed script for making it work for several routes?

Answer 1

You can use this script: (Reference)

# CHANGE LAYER NAMES
networkLayer = QgsProject.instance().mapLayersByName('networkLayerName')[0]
pointLayer = QgsProject.instance().mapLayersByName('pointLayerName')[0]

output_folder = "/path/to/a/folder" # ADD A FOLDER PATH

route_field_index = pointLayer.fields().indexFromName('route')
unique_routes = pointLayer.uniqueValues(route_field_index)

for unique_route in unique_routes:

    pointLayer.selectByExpression(f"route='{unique_route}'")

    stops = []
    for feat in pointLayer.selectedFeatures():
        stops.append((feat['stop'], feat.geometry().asPoint()))

    #sort by order column
    stops.sort(key=lambda x: x[0])
    paths = []
    for i, (order, point) in enumerate(stops[0:-1]):
        endPoint = stops[i + 1][1]
        parameters = {'INPUT': networkLayer,
                      'STRATEGY': 0,
                      'DIRECTION_FIELD': '',
                      'VALUE_FORWARD': '',
                      'VALUE_BACKWARD': '',
                      'VALUE_BOTH': '',
                      'DEFAULT_DIRECTION': 2,
                      'SPEED_FIELD': '',
                      'DEFAULT_SPEED': 50.0,
                      'TOLERANCE': 20.0,
                      'START_POINT': point,
                      'END_POINT': endPoint,
                      'OUTPUT': 'memory:'}

        path = processing.run('qgis:shortestpathpointtopoint', parameters)['OUTPUT']
        paths.append(path)    
    
    output = f'{output_folder}/{unique_route}.shp'
    pathsMerged = processing.run('qgis:mergevectorlayers',
                                 {'LAYERS': paths,
                                  'OUTPUT': output})['OUTPUT']
                                  
    vlayer = QgsVectorLayer(pathsMerged, str(unique_route), 'ogr')
    QgsProject.instance().addMapLayer(vlayer)

I didn't merge the route layers. You may need to merge them.