def __init__(self, instance, route: List[int], q_init: float, multi_insert: bool = True, check_tri: bool = False):
"""Initiates a Solver for the FRVCP.
Args:
instance: either the filename (str) of a problem instance or a
dictionary containing the required info. Typically the problem
instance is already in a compliant JSON file. However, if a
filename ending in ".xml" is passed, it is assumed to be a
VRP-REP instance, and it will be translated.
route: A list of integers representing the fixed route to be
traveled by the vehicle
q_init: The energy with which the EV begins the route
multi_insert: A boolean specifying whether the EV is allowed to
visit multiple CSs between stops in the route
check_tri: A boolean specifying whether to verify that the triangle
inequality holds for the instance's time and energy matrices.
Default is False, since this adds significant computation time.
"""
# if passed an XML file, attempt to translate it
if isinstance(instance, (str)) and instance[-4:] == ".xml":
print("INFO: Passed instance is an XML file. " +
"Assuming it is a VRP-REP instance and attempting to translate it...")
instance = translator.translate(instance)
print("INFO: Instance translated.")
self.instance = core.FrvcpInstance(instance, check_tri)
self._q_init = q_init
self._route = route
self._multi_insert = multi_insert
self.solution = None
This example follows the "Example Usage" seciton (5.2) from the original research
article describing frvcpy.
That article may be found here:
https://doi.org/10.1287/ijoc.2020.1035
The script translates an instance from the VRP-REP format, solves an FRVCP on the
instance, and writes the solution to file.
"""
from frvcpy.translator import translate
from frvcpy.solver import Solver
if __name__ == "__main__":
# Translate the VRP-REP instance.
frvcp_instance = translate("../data/vrprep-instance.xml")
route = [0, 40, 12, 33, 38, 16, 0] # route to make energy feasible
q_init = frvcp_instance["max_q"] # EV begins with max battery capacity
# Initialize solver with the instance, route, and initial charge.
frvcp_solver = Solver(frvcp_instance, route, q_init)
# Run the algorithm.
duration, feas_route = frvcp_solver.solve()
# Write a VRP-REP compliant solution file.
frvcp_solver.write_solution("../results/my-solution.xml",
instance_name="frvcpy-instance")
print(f"Duration: {duration:.4}")
def test_translation(self):
"""Translate an instance, compare it to a known reference"""
frvcp_instance = translator.translate(self.MANUSCRIPT_INSTANCE)
assertDeepAlmostEqual(self, frvcp_instance, self.ref_instance, 3)