culebra.solution.tsp.Solution class

class Solution(species: Species, fitness_cls: Type[Fitness], path: Sequence[int] | None = None)

Construct a default solution.

Parameters:

• species (species_cls) – The species the solution will belong to

• fitness (Fitness) – The solution’s fitness class

• path (Sequence of int) – Initial path

Raises:

• TypeError – If species is not a valid species

• TypeError – If fitness_cls is not a valid fitness class

Class attributes

Solution.species_cls = <class 'culebra.solution.tsp.Species'>

Class for the species used by the Solution class to constrain all its instances.

Class methods

classmethod Solution.load_pickle(filename: str) → Base

Load a pickled object from a file.

Parameters:

filename (str) – The file name.

Raises:

• TypeError – If filename is not a valid file name

• ValueError – If the filename extension is not PICKLE_FILE_EXTENSION

Properties

property Solution.species: Species

Get the solution’s species.

Returns:

The species

Return type:

Species

property Solution.fitness: Fitness

Get and set the solution’s fitness.

Getter:

Return the current fitness

Setter:

Set a new Fitness

Type:

Fitness

property Solution.path: Sequence[int]

Get and set the path.

Getter:

Return the path.

Setter:

Set the new path. An array-like object of node indices is expected

Type:

Sequence of int

Raises:

ValueError – If the new path does not meet the species constraints.

Methods

Solution.save_pickle(filename: str) → None

Pickle this object and save it to a file.

Parameters:

filename (str) – The file name.

Raises:

• TypeError – If filename is not a valid file name

• ValueError – If the filename extension is not PICKLE_FILE_EXTENSION

Solution.dominates(other: Solution) → bool

Dominate operator.

Parameters:

other (Solution) – Other solution

Returns:

True if each objective of the solution is not strictly worse than the corresponding objective of other and at least one objective is strictly better.

Return type:

bool

Solution.delete_fitness() → None

Delete the solution’s fitness.

Private methods

abstract Solution._setup() → None

Init the nodes of this solution.

This method must be overridden by subclasses.

Raises:

NotImplementedError – if has not been overridden

Dunder methods

Solution.__hash__() → int

Return the hash number for this solution.

The hash number is used for equality comparisons. Currently is implemented as the hash of the solution’s string representation.

Solution.__eq__(other: Solution) → bool

Equality test.

Parameters:

other (Solution) – Other solution

Returns:

True if other codes the same solution, or False otherwise

Return type:

bool

Solution.__ne__(other: Solution) → bool

Not equality test.

Parameters:

other (Solution) – Other solution

Returns:

False if other codes the same solutions, or True otherwise

Return type:

bool

Solution.__lt__(other: Solution) → bool

Less than operator.

Parameters:

other (Solution) – Other solution

Returns:

True if the solution’s fitness is less than the other’s fitness

Return type:

bool

Solution.__gt__(other: Solution) → bool

Greater than operator.

Parameters:

other (Solution) – Other solution

Returns:

True if the solution’s fitness is greater than the other’s fitness

Return type:

bool

Solution.__le__(other: Solution) → bool

Less than or equal to operator.

Parameters:

other (Solution) – Other solution

Returns:

True if the solution’s fitness is less than or equal to the other’s fitness

Return type:

bool

Solution.__ge__(other: Solution) → bool

Greater than or equal to operator.

Parameters:

other (Solution) – Other solution

Returns:

True if the solution’s fitness is greater than or equal to the other’s fitness

Return type:

bool

Solution.__str__() → str

Return the solution as a string.

A symmetric tsp problem is assumed. Thus, all rotations of paths [0, 1, …, n] and [n, …, 1, 0] are considered the same path.

The path is rolled to start with the node with smallest index.