qiskit.optimization.applications.ising.vehicle_routing
Converts vehicle routing instances into a list of Paulis, and provides some related routines (extracting a solution, checking its objective function value).
Functions
get_operator(instance, n, K) | Converts an instance of a vehicle routing problem into a list of Paulis. |
get_vehiclerouting_cost(instance, n, K, x_sol) | Computes the cost of a solution to an instance of a vehicle routing problem. |
get_vehiclerouting_matrices(instance, n, K) | Constructs auxiliary matrices from a vehicle routing instance, |
get_vehiclerouting_solution(instance, n, K, …) | Tries to obtain a feasible solution (in vector form) of an instance |
get_operator
get_operator(instance, n, K)
Converts an instance of a vehicle routing problem into a list of Paulis.
Parameters
- instance (numpy.ndarray) – a customers-to-customers distance matrix.
- n (integer) – the number of customers.
- K (integer) – the number of vehicles available.
Returns
operator for the Hamiltonian.
Return type
get_vehiclerouting_cost
get_vehiclerouting_cost(instance, n, K, x_sol)
Computes the cost of a solution to an instance of a vehicle routing problem.
Parameters
- instance (numpy.ndarray) – a customers-to-customers distance matrix.
- n (integer) – the number of customers.
- K (integer) – the number of vehicles available.
- x_sol (numpy.ndarray) – a solution, i.e., a path, in its binary representation.
Returns
objective function value.
Return type
float
get_vehiclerouting_matrices
get_vehiclerouting_matrices(instance, n, K)
Constructs auxiliary matrices from a vehicle routing instance,
which represent the encoding into a binary quadratic program. This is used in the construction of the qubit ops and computation of the solution cost.
Parameters
- instance (numpy.ndarray) – a customers-to-customers distance matrix.
- n (integer) – the number of customers.
- K (integer) – the number of vehicles available.
Returns
a matrix defining the interactions between variables. a matrix defining the contribution from the individual variables. the constant offset.
Return type
tuple(numpy.ndarray, numpy.ndarray, float)
get_vehiclerouting_solution
get_vehiclerouting_solution(instance, n, K, result)
Tries to obtain a feasible solution (in vector form) of an instance
of vehicle routing from the results dictionary.
Parameters
- instance (numpy.ndarray) – a customers-to-customers distance matrix.
- n (integer) – the number of customers.
- K (integer) – the number of vehicles available.
- result (dictionary) – a dictionary obtained by QAOA.run or VQE.run containing key ‘eigvecs’.
Returns
a solution, i.e., a path, in its binary representation.
Return type
numpy.ndarray
#TODO: support statevector simulation, results should be a statevector or counts format, not
a result from algorithm run