How can I solve a multi-class traffic assignment

Question

I am working on a project which needs to use aequilibrae python package. I am getting an issue while doing a multi-class equilibrium task. I am getting an error after assig.execute() as "ValueError: operands could not be broadcast together with shapes (11202,) (9184,)". The shape of my graphs are different for different traffic classes in each traffic class function. The graphs are different as I am using different set of networks for each traffic class.

These are the last few lines of my script.

%%time

aem_usa = AequilibraeMatrix()
aem_china = AequilibraeMatrix()
aem_neutral= AequilibraeMatrix()

os.chdir("D:/Professional/Mir/1_multi_class_analysis/7_matrix_bin/") #setting directory

#load aem file
aem_usa.load("Demand_usa.aem")
aem_usa.computational_view(["matrix"])

aem_china.load("Demand_china.aem")
aem_china.computational_view(["matrix"])

aem_neutral.load("Demand_neutral.aem")
aem_neutral.computational_view(["matrix"])

#now assign classes
tc_usa= TrafficClass("usa_flow", g_usa, aem_usa)
tc_china=TrafficClass("china_flow", g_china, aem_china)
#tc_china.set_pce(1)
tc_neutral= TrafficClass("neutral_flow", g_neutral, aem_neutral)

#set classes
assig= TrafficAssignment()
assig.set_classes([tc_china, tc_neutral])
assig.set_vdf("BPR")
assig.set_vdf_parameters({"alpha":0, "beta":1})
assig.set_capacity_field("capacity")
assig.set_algorithm("all-or-nothing")
assig.max_iter = 100
assig.rgap_target = 1e-6
assig.execute()

This is the error



{
    "name": "ValueError",
    "message": "operands could not be broadcast together with shapes (11202,) (9184,) ",
    "stack": "---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
File <timed exec>:36

File c:\\Users\\Raisul\\anaconda3\\envs\\my_env\\Lib\\site-packages\\aequilibrae\\paths\\traffic_assignment.py:432, in TrafficAssignment.execute(self, log_specification)
    430 if log_specification:
    431     self.log_specification()
--> 432 self.assignment.execute()

File c:\\Users\\Raisul\\anaconda3\\envs\\my_env\\Lib\\site-packages\\aequilibrae\\paths\\linear_approximation.py:388, in LinearApproximation.execute(self)
    384 self.__maybe_create_path_file_directories()
    386 for c in self.traffic_classes:  # type: TrafficClass
    387     # cost = c.fixed_cost / c.vot + self.congested_time #  now only once
--> 388     cost = c.fixed_cost + self.congested_time
    389     aggregate_link_costs(cost, c.graph.compact_cost, c.results.crosswalk)
    391     aon = allOrNothing(c.matrix, c.graph, c._aon_results)

ValueError: operands could not be broadcast together with shapes (11202,) (9184,) "
}

How can I get my result while the shape of g_usa and g_china are still different?

PCamargo · Accepted Answer · 2024-07-22 11:08:04Z

0

First a warning: This is not a programming question, as the answer is not in the code. second a disclosure: I am the creator of AequilibraE, the package in question here.

Multi-class traffic assignment only makes sense where the underlying supernetwork is the same, with different graphs for each class being assigned. In the context of static traffic assignment, it only makes sense to do it if performing some sort of equilibrium assignment where there is a feedback (equilibration) mechanism recomputing link costs via the use of volume-delay function, which takes into consideration.

In this case, just perform two separate assignments (and make sure the centroids in the graph are compatible with those in the matrix) and combine the results afterwards.

answered Jul 22, 2024 at 11:08

PCamargo

6037 silver badges28 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How can I solve a multi-class traffic assignment

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related