Particle Swarm Optimization#

class Particle(position: ndarray | list | Position | None = None, velocity=None, f: ObjectiveFunction | None = None)#

Bases: object

Defines a particle used in PSO.

__init__(position: ndarray | list | Position | None = None, velocity=None, f: ObjectiveFunction | None = None)#
Parameters:

position – The initial position of the particle. If unspecified,

the position will default to a uniformly sampled vector within the bounds of the ObjectiveFunction (if provided). :param velocity: The initial velocity. Defaults to a vector of zeros. :param f: The objective function to be optimized.

property personal_best: Position#

Returns the personal best position as a Position object.

property position: Position#

Returns the position as a Position object.

property velocity: ndarray#

Returns the current velocity as a Numpy array.

update_personal_best()#
evaluate(f: ObjectiveFunction)#

Evaluates the Particle’s position.

class PSO(n_particles: int, obj_func, w: float, c1: float, c2: float)#

Bases: Algorithm

__init__(n_particles: int, obj_func, w: float, c1: float, c2: float)#
Parameters:

  • n_particles – The number of particles in the Swarm.

  • obj_func – The ObjectiveFunction used to initialize the particles.

  • w – Inertia weight.

  • c1 – Cognitive acceleration coefficient.

  • c2 – Social acceleration coefficient.

iterate(obj_func) → None#

The only function that must be overridden when implementing your own algorithm. This function must be the logic of one iteration of your algorithm.

Parameters:

f – The ObjectiveFunction to optimize.

collection()#
std_velocity(particle: Particle, social_best: Position, w: float = 0.74, c1: float = 1.4, c2: float = 1.4)#

The default velocity update function.

Parameters:

  • particle – The particle whose velocity is to be updated.

  • social_best – The social guide.

  • w – Inertia weight.

  • c1 – Cognitive acceleration coefficient.

  • c2 – Social acceleration coefficient.

particles(n: int, f: ObjectiveFunction)#
global_best(particles: List[Particle], f: ObjectiveFunction)#