Initial support for areas

[EwoutH]

This PR adds initial support for Areas in UXsim. I approached it in the following way:

• Introduced a new area attribute in the Node class to define the area a node belongs to.
• Modified the __init__ method of the Node class to accept an optional area parameter.
• Added W.NODES_AREA_DICT to store nodes grouped by their respective areas.
• Implemented update_nodes_area_dict() to populate the area dictionary with nodes.
• Added a method get_random_node_in_area() to retrieve a random node within a specified area.
• Updated finalize_scenario() to call update_nodes_area_dict() ensuring the area dictionary is up to date.

In my model, I use it like this:

When adding the nodes to the model, I define the area keyword

# Create Nodes in UXsim from OSMnx graph nodes
for node_id, data in road_network.nodes(data=True):
    mrdh65 = data1.pc4_to_mrdh65[int(data['postcode'])]
    world.addNode(name=str(node_id), x=data['x'], y=data['y'], area=mrdh65)

When planning trips, I ask to get a random node from an area, which I use as starting point.

starting_node = self.model.uxsim_world.get_random_node_in_area(self.mrdh65)
target_node = self.model.uxsim_world.get_random_node_in_area(destination)

# Add the car trip to the UXsim world
self.model.uxsim_world.addVehicle(orig=starting_node, dest=target_node, departure_time=self.model.simulator.time)

More features could be added. But before I develop this further, I would like to know @toruseo if this is a desired development direction.

I could also understand that you want to approach this subject differently, by making Areas objects or by tracking areas in a different way.

Part of #102.

[toruseo]

Thank you very much for your effort.

But I think "area" variable is better to be defined more generally and should not depends on the simulator too much. This is because "area" will be useful as a input and output for the simulation but will not be utilized by the simulation model itself.

For example, a node may belong to multiple areas in general (e.g., an intersection belong to a city and a prefecture). But for some particular purposes, areas need to be mutually exclusive. Therefore, I think it is better to leave this kind of setting to the users rather than implementing it within the simulator

I think I can implement them today.

[EwoutH]

Thanks for getting back! I agree adding only one single area per node might be a bit limiting.

I will open a separate PR to add get_random_node_in_area as util.

[EwoutH]

For reference, this is what I needed to do to work with the latest uxsim (that being 4687807):

• EwoutH/urban-self-driving-effects@432ef66

So I think you made the right call: The attribute is useful, and I didn't need to add too much code on my part.

[EwoutH]

Closing this PR, as current functionality is either enclosed in current UXsim or can easily be added like shown above.