def _transition_packs(self, agents, n_c):
"""Transits coyotes between packs (Eq. 4).
Args:
agents (list): List of agents.
n_c (int): Number of coyotes per pack.
"""
# Calculates the eviction probability
p_e = 0.005 * len(agents)
# Generates a uniform random number
r1 = r.generate_uniform_random_number()
# If random number is smaller than eviction probability
if r1 < p_e:
# Gathers two random packs
p1 = r.generate_integer_random_number(high=self.n_p)
p2 = r.generate_integer_random_number(high=self.n_p)
# Gathers two random coyotes
c1 = r.generate_integer_random_number(high=n_c)
c2 = r.generate_integer_random_number(high=n_c)
# Calculates their indexes
i = n_c * p1 + c1
j = n_c * p2 + c2
# Performs a swap betweeh them
agents[i], agents[j] = copy.deepcopy(agents[j]), copy.deepcopy(
agents[i])
def _mutation(self, alpha):
"""Performs the mutation over an offspring (s. 3.4).
Args:
alpha (Agent): Offspring to be mutated.
Returns:
The mutated offspring.
"""
# Checks if the number of variables is bigger than one
if alpha.n_variables > 1:
# Samples a random integer
r1 = r.generate_integer_random_number(0, alpha.n_variables)
# Samples the second integer
r2 = r.generate_integer_random_number(0,
alpha.n_variables,
exclude_value=r1)
# Swaps the randomly selected variables
alpha.position[r1], alpha.position[r2] = alpha.position[
r2], alpha.position[r1]
return alpha
def update(self, space, function):
"""Wraps Symbiotic Organisms Search over all agents and variables.
Args:
space (Space): Space containing agents and update-related information.
function (Function): A Function object that will be used as the objective function.
"""
# Iterates through all agents
for i, agent in enumerate(space.agents):
# Generates a random integer for mutualism and performs it
j = r.generate_integer_random_number(0,
len(space.agents),
exclude_value=i)
self._mutualism(agent, space.agents[j], space.best_agent, function)
# Re-generates a random integer for commensalism and performs it
j = r.generate_integer_random_number(0,
len(space.agents),
exclude_value=i)
self._commensalism(agent, space.agents[j], space.best_agent,
function)
# Re-generates a random integer for parasitism and performs it
j = r.generate_integer_random_number(0,
len(space.agents),
exclude_value=i)
self._parasitism(agent, space.agents[j], function)
def _update(self, agents, function, n_c):
"""Method that wraps Coyote Optimization Algorithm over all agents and variables.
Args:
agents (list): List of agents.
function (Function): A Function object that will be used as the objective function.
n_c (int): Number of agents per pack.
"""
# Iterates through all packs
for i in range(self.n_p):
# Gets the agents for the specified pack
pack_agents = self._get_agents_from_pack(agents, i, n_c)
# Gathers the alpha coyote (Eq. 5)
alpha = pack_agents[0]
# Computes the cultural tendency (Eq. 6)
tendency = np.median(np.array(
[agent.position for agent in pack_agents]),
axis=0)
# Iterates through all coyotes in the pack
for agent in pack_agents:
# Makes a deepcopy of current coyote
a = copy.deepcopy(agent)
# Generates two random integers
cr1 = r.generate_integer_random_number(high=len(pack_agents))
cr2 = r.generate_integer_random_number(high=len(pack_agents))
# Calculates the alpha and pack influences
lambda_1 = alpha.position - pack_agents[cr1].position
lambda_2 = tendency - pack_agents[cr2].position
# Generates two random uniform numbers
r1 = r.generate_uniform_random_number()
r2 = r.generate_uniform_random_number()
# Updates the social condition (Eq. 12)
a.position += r1 * lambda_1 + r2 * lambda_2
# Checks the agent's limits
a.clip_limits()
# Evaluates the agent (Eq. 13)
a.fit = function(a.position)
# If the new potision is better than current agent's position (Eq. 14)
if a.fit < agent.fit:
# Replaces the current agent's position
agent.position = copy.deepcopy(a.position)
# Also replaces its fitness
agent.fit = copy.deepcopy(a.fit)
# Performs transition between packs (Eq. 4)
self._transition_packs(agents, n_c)
def test_generate_integer_random_number():
integer_array = random.generate_integer_random_number(0, 1, None, 5)
assert integer_array.shape == (5, )
integer_array = random.generate_integer_random_number(0, 10, 1, 5)
assert integer_array.shape == (5, )
def _update(self, agents, function, iteration, n_iterations):
"""Method that wraps Artificial Butterfly Optimization over all agents and variables.
Args:
agents (list): List of agents.
function (Function): A Function object that will be used as the objective function.
iteration (int): Current iteration.
n_iterations (int): Maximum number of iterations.
"""
# Sorting agents
agents.sort(key=lambda x: x.fit)
# Calculates the number of sunspot butterflies
n_sunspots = int(self.sunspot_ratio * len(agents))
# Iterates through all sunspot butterflies
for agent in agents[:n_sunspots]:
# Generates the index for a random sunspot butterfly
k = r.generate_integer_random_number(0, len(agents))
# Performs a flight mode using sunspot butterflies (eq. 1)
agent.position, agent.fit, _ = self._flight_mode(agent, agents[k], function)
# Iterates through all canopy butterflies
for agent in agents[n_sunspots:]:
# Generates the index for a random canopy butterfly
k = r.generate_integer_random_number(0, len(agents) - n_sunspots)
# Performs a flight mode using canopy butterflies (eq. 1)
agent.position, agent.fit, is_better = self._flight_mode(agent, agents[k], function)
# If there was not fitness replacement
if not is_better:
# Generates the index for a random butterfly
k = r.generate_integer_random_number(0, len(agents))
# Generates random uniform number
r1 = r.generate_uniform_random_number()
# Calculates `D` (eq. 4)
D = np.fabs(2 * r1 * agents[k].position - agent.position)
# Generates another random uniform number
r2 = r.generate_uniform_random_number()
# Linearly decreases `a`
a = (self.a - self.a * (iteration / n_iterations))
# Updates the agent's position (eq. 3)
agent.position = agents[k].position - 2 * a * r2 - a * D
# Clips its limits
agent.clip_limits()
# Re-calculates its fitness
agent.fit = function(agent.position)
def _crossover(self, agents: List[Agent],
trial_agents: List[Agent]) -> None:
"""Performs the crossover operator.
Args:
agents: List of agents.
trial_agents: List of trial agents.
"""
# Defines the number of agents and variables
n_agents = len(agents)
n_variables = agents[0].n_variables
# Creates a crossover map
cross_map = np.ones((n_agents, n_variables))
# Generates the `a` and `b` random uniform numbers
a = r.generate_uniform_random_number()
b = r.generate_uniform_random_number()
# If `a` is smaller than `b`
if a < b:
# Iterates through all agents
for i in range(n_agents):
# Generates a uniform random number
r1 = r.generate_uniform_random_number()
# Calculates the number of non-crosses
non_crosses = int(self.mix_rate * r1 * n_variables)
# Iterates through the number of non-crosses
for _ in range(non_crosses):
# Generates a random decision variable index
u = r.generate_integer_random_number(high=n_variables)
# Turn off the crossing on this specific point
cross_map[i][u] = 0
# If `a` is bigger than `b`
else:
# Iterates through all agents
for i in range(n_agents):
# Generates a random decision variable index
j = r.generate_integer_random_number(high=n_variables)
# Turn off the crossing on this specific point
cross_map[i][j] = 0
# Iterates through all agents
for i in range(n_agents):
# Iterates through all decision variables
for j in range(n_variables):
# If it is supposed to cross according to the map
if cross_map[i][j]:
# Makes a deep copy on such position
trial_agents[i].position[j] = copy.deepcopy(
agents[i].position[j])
def update(self, space: Space, function: Function) -> None:
"""Wraps Coyote Optimization Algorithm over all agents and variables.
Args:
space: Space containing agents and update-related information.
function: A Function object that will be used as the objective function.
"""
# Iterates through all packs
for i in range(self.n_p):
# Gets the agents for the specified pack
pack_agents = self._get_agents_from_pack(space.agents, i)
# Gathers the alpha coyote (eq. 5)
alpha = pack_agents[0]
# Computes the cultural tendency (eq. 6)
tendency = np.median(np.array(
[agent.position for agent in pack_agents]),
axis=0)
# Iterates through all coyotes in the pack
for agent in pack_agents:
# Makes a deep copy of current coyote
a = copy.deepcopy(agent)
# Generates two random integers
cr1 = r.generate_integer_random_number(high=len(pack_agents))
cr2 = r.generate_integer_random_number(high=len(pack_agents))
# Calculates the alpha and pack influences
lambda_1 = alpha.position - pack_agents[cr1].position
lambda_2 = tendency - pack_agents[cr2].position
# Generates two random uniform numbers
r1 = r.generate_uniform_random_number()
r2 = r.generate_uniform_random_number()
# Updates the social condition (eq. 12)
a.position += r1 * lambda_1 + r2 * lambda_2
# Checks the agent's limits
a.clip_by_bound()
# Evaluates the agent (eq. 13)
a.fit = function(a.position)
# If the new potision is better than current agent's position (eq. 14)
if a.fit < agent.fit:
# Replaces the current agent's position and fitness
agent.position = copy.deepcopy(a.position)
agent.fit = copy.deepcopy(a.fit)
# Performs transition between packs (eq. 4)
self._transition_packs(space.agents)
def _update(self, agents, best_agent, function):
"""Method that wraps global and local pollination updates over all agents and variables.
Args:
agents (list): List of agents.
best_agent (Agent): Global best agent.
function (Function): A Function object that will be used as the objective function.
"""
# Iterate through all agents
for agent in agents:
# Creates a temporary agent
a = copy.deepcopy(agent)
# Generating an uniform random number
r1 = r.generate_uniform_random_number()
# Check if generated random number is bigger than probability
if r1 > self.p:
# Update a temporary position according to global pollination
a.position = self._global_pollination(agent.position,
best_agent.position)
else:
# Generates an uniform random number
epsilon = r.generate_uniform_random_number()
# Generates an index for flower k
k = r.generate_integer_random_number(0, len(agents))
# Generates an index for flower l
l = r.generate_integer_random_number(0,
len(agents),
exclude_value=k)
# Update a temporary position according to local pollination
a.position = self._local_pollination(agent.position,
agents[k].position,
agents[l].position,
epsilon)
# Check agent limits
a.clip_limits()
# Calculates the fitness for the temporary position
a.fit = function(a.position)
# If new fitness is better than agent's fitness
if a.fit < agent.fit:
# Copy its position to the agent
agent.position = copy.deepcopy(a.position)
# And also copy its fitness
agent.fit = copy.deepcopy(a.fit)
def update(self, space: Space, function: Function) -> None:
"""Wraps Flower Pollination Algorithm over all agents and variables.
Args:
space: Space containing agents and update-related information.
function: A Function object that will be used as the objective function.
"""
# Iterates through all agents
for agent in space.agents:
# Creates a temporary agent
a = copy.deepcopy(agent)
# Generates an uniform random number
r1 = r.generate_uniform_random_number()
# Check if generated random number is bigger than probability
if r1 > self.p:
# Updates a temporary position according to global pollination
a.position = self._global_pollination(
agent.position, space.best_agent.position)
else:
# Generates an uniform random number
epsilon = r.generate_uniform_random_number()
# Generates an index for flower `k` and flower `l`
k = r.generate_integer_random_number(0, len(space.agents))
l = r.generate_integer_random_number(0,
len(space.agents),
exclude_value=k)
# Updates a temporary position according to local pollination
a.position = self._local_pollination(
agent.position,
space.agents[k].position,
space.agents[l].position,
epsilon,
)
# Checks agent's limits
a.clip_by_bound()
# Calculates the fitness for the temporary position
a.fit = function(a.position)
# If new fitness is better than agent's fitness
if a.fit < agent.fit:
# Copies its position and fitness to the agent
agent.position = copy.deepcopy(a.position)
agent.fit = copy.deepcopy(a.fit)
def _parasitism_phase(
self,
space: Space,
n_crows: int,
n_cuckoos: int,
iteration: int,
n_iterations: int,
):
"""Performs the parasitism phase using the current number of cuckoos.
Args:
space: Space containing agents and update-related information.
n_crows: Number of crows.
n_cuckoos: Number of cuckoos.
iteration: Current iteration.
n_iterations: Maximum number of iterations.
"""
# Gathers the cuckoos
cuckoos = space.agents[n_crows:n_crows + n_cuckoos]
# Calculates a list of cuckoos' fitness
fitness = [cuckoo.fit for cuckoo in cuckoos]
# Calculates the probability of selection
p = iteration / n_iterations
# Iterates through all cuckoos
for cuckoo in cuckoos:
# Selects a cuckoo through tournament selection
s = g.tournament_selection(fitness, 1)[0]
# Selects two random agents from the space
i = r.generate_integer_random_number(high=space.n_agents)
j = r.generate_integer_random_number(high=space.n_agents,
exclude_value=i)
# Creates a bernoulli distribution to preserve or not variables (eq. 12)
k = d.generate_bernoulli_distribution(1 - p, cuckoo.n_variables)
k = np.expand_dims(k, -1)
# Calculates the gaussian-based step distribution (eq. 11)
rand = r.generate_uniform_random_number()
S_g = (space.agents[i].position - space.agents[j].position) * rand
# Updates the cuckoo's position and clips its limits (eq. 10)
cuckoo.position = space.agents[s].position + S_g * k
cuckoo.clip_by_bound()
def update(self, space, function):
"""Wraps Wind Driven Optimization over all agents and variables.
Args:
space (Space): Space containing agents and update-related information.
function (Function): A function object.
"""
# Iterates through all agents
for i, agent in enumerate(space.agents):
# Generates a random index based on the number of agents
index = r.generate_integer_random_number(0, len(space.agents))
# Updates velocity (eq. 15)
self.velocity[i] = (1 - self.alpha) * self.velocity[i] - self.g * agent.position + \
(self.RT * np.abs(1 / (index + 1) - 1) * (space.best_agent.position - agent.position)) + \
(self.c * self.velocity[index] / (index + 1))
# Clips the velocity values between [-v_max, v_max]
self.velocity = np.clip(self.velocity, -self.v_max, self.v_max)
# Updates agent's position (eq. 16)
agent.position += self.velocity[i]
# Checks agent limits
agent.clip_by_bound()
# Evaluates agent
agent.fit = function(agent.position)
def _update(self, agents, memory):
"""Method that wraps the Crow Search Algorithm over all agents and variables.
Args:
agents (list): List of agents.
memory (np.array): Array of memories.
"""
# Iterates through every agent
for agent in agents:
# Generates uniform random numbers
r1 = r.generate_uniform_random_number()
r2 = r.generate_uniform_random_number()
# Generates a random integer (e.g. selects the crow)
j = r.generate_integer_random_number(high=len(agents))
# Checks if first random number is greater than awareness probability
if r1 >= self.AP:
# Updates agent's position (Eq. 2)
agent.position += r2 * self.fl * (memory[j] - agent.position)
# If random number is smaller than probability
else:
# Generate a random position
for j, (lb, ub) in enumerate(zip(agent.lb, agent.ub)):
# For each decision variable, we generate uniform random numbers
agent.position[j] = r.generate_uniform_random_number(lb, ub, size=agent.n_dimensions)
def _send_onlooker(self, agents: List[Agent], function: Function) -> None:
"""Sends onlooker bees to select new food sources (eq. 2.1).
Args:
agents: List of agents.
function: A function object.
"""
# Calculates the fitness somatory
total = sum(agent.fit for agent in agents)
# Defines food sources' counter
k = 0
# While counter is less than the amount of food sources
while k < len(agents):
# We iterate through every agent
for i, agent in enumerate(agents):
# Creates a random uniform number
r1 = r.generate_uniform_random_number()
# Calculates the food source's probability
probs = (agent.fit / (total + c.EPSILON)) + 0.1
# If the random number is smaller than food source's probability
if r1 < probs:
# We need to increment the counter
k += 1
# Gathers a random source to be used
source = r.generate_integer_random_number(0, len(agents))
# Evaluate its location
self._evaluate_location(agent, agents[source], function, i)
def _nesting_phase(self, space: Space, n_crows: int):
"""Performs the nesting phase using the current number of crows.
Args:
space: Space containing agents and update-related information.
n_crows: Number of crows.
"""
# Gathers the crows
crows = space.agents[:n_crows]
# Iterates through all crows
for i, crow in enumerate(crows):
# Generates a random index
idx = r.generate_integer_random_number(high=space.n_agents,
exclude_value=i)
# Calculates the step from Lévy distribution (eq. 7)
step = d.generate_levy_distribution(size=crow.n_variables)
step = np.expand_dims(step, axis=1)
# Updates the crow's position and clips its bounds (eq. 6 and 8)
crow.position = 0.01 * step * (space.agents[idx].position -
crow.position)
crow.clip_by_bound()
def _update(self, agents, function):
"""Method that wraps the update pipeline over all agents and variables.
Args:
agents (list): List of agents.
function (Function): A function object.
"""
# Calculates a random index
i = r.generate_integer_random_number(0, len(agents))
# Generates a new harmony
agent = self._generate_new_harmony(agents[i])
# Checking agent limits
agent.clip_limits()
# Calculates the new harmony fitness
agent.fit = function(agent.position)
# Sorting agents
agents.sort(key=lambda x: x.fit)
# If newly generated agent fitness is better
if agent.fit < agents[-1].fit:
# Updates the corresponding agent's position
agents[-1].position = copy.deepcopy(agent.position)
# And its fitness as well
agents[-1].fit = copy.deepcopy(agent.fit)
def _parasitism(self, agent_i, agent_j, function):
"""Performs the parasitism operation.
Args:
agent_i (Agent): Selected `i` agent.
agent_j (Agent): Selected `j` agent.
function (Function): A Function object that will be used as the objective function.
"""
# Creates a temporary parasite agent
p = copy.deepcopy(agent_i)
# Generates a integer random number
r1 = r.generate_integer_random_number(0, agent_i.n_variables)
# Updates its position on selected variable with a uniform random number
p.position[r1] = r.generate_uniform_random_number(p.lb[r1], p.ub[r1])
# Checks its limits
p.clip_limits()
# Evaluates its position
p.fit = function(p.position)
# If the new potision is better than agent's `j` position
if p.fit < agent_j.fit:
# Replaces the agent's `j` position
agent_j.position = copy.deepcopy(p.position)
# Also replaces its fitness
agent_j.fit = copy.deepcopy(p.fit)
def _crossover(self, agents, idx):
"""Performs the crossover between selected agent and a randomly agent (eq. 21).
Args:
agents (list): List of agents.
idx (int): Selected agent.
Returns:
An agent after suffering a crossover operator.
"""
# Makes a deepcopy of an agent
a = copy.deepcopy(agents[idx])
# Samples a random integer
m = r.generate_integer_random_number(0, len(agents), exclude_value=idx)
# Calculates the current crossover probability
Cr = self.Cr * ((agents[idx].fit - agents[0].fit) /
(agents[-1].fit - agents[0].fit + c.EPSILON))
# Iterates through all variables
for j in range(a.n_variables):
# Generating a uniform random number
r1 = r.generate_uniform_random_number()
# If sampled uniform number if smaller than crossover probability
if r1 < Cr:
# Gathers the position from the selected agent
a.position[j] = copy.deepcopy(agents[m].position[j])
return a
def update(self, space, function, iteration, n_iterations):
"""Wraps Equilibrium Optimizer over all agents and variables.
Args:
space (Space): Space containing agents and update-related information.
function (Function): A Function object that will be used as the objective function.
iteration (int): Current iteration.
n_iterations (int): Maximum number of iterations.
"""
# Calculates the equilibrium and average concentrations
self._calculate_equilibrium(space.agents)
C_avg = self._average_concentration(function)
# Makes a pool of both concentrations and their average (eq. 7)
C_pool = self.C + [C_avg]
# Calculates the time (eq. 9)
t = (1 - iteration / n_iterations)**(self.a2 * iteration /
n_iterations)
# Iterates through all agents
for agent in space.agents:
# Generates a integer between [0, 5) to select the concentration
i = rnd.generate_integer_random_number(0, 5)
# Generates two uniform random vectors (eq. 11)
r = rnd.generate_uniform_random_number(size=(agent.n_variables,
agent.n_dimensions))
lambd = rnd.generate_uniform_random_number(
size=(agent.n_variables, agent.n_dimensions))
# Calculates the exponential term (eq. 11)
F = self.a1 * np.sign(r - 0.5) * (np.exp(-lambd * t) - 1)
# Generates two uniform random numbers
r1 = rnd.generate_uniform_random_number()
r2 = rnd.generate_uniform_random_number()
# If `r2` is bigger than generation probability (eq. 15)
if r2 >= self.GP:
# Defines generation control parameter as 0.5 * r1
GCP = 0.5 * r1
# If `r2` is smaller than generation probability
else:
# Defines generation control parameter as zero
GCP = 0
# Calculates the initial generation value (eq. 14)
G_0 = GCP * (C_pool[i].position - lambd * agent.position)
# Calculates the generation value (eq. 13)
G = G_0 * F
# Updates agent's position (eq. 16)
agent.position = C_pool[i].position + (
agent.position -
C_pool[i].position) * F + (G / (lambd * self.V)) * (1 - F)
def _update(self, agents, best_agent, function, height, length):
"""Method that wraps Water Wave Optimization over all agents and variables.
Args:
agents (list): List of agents.
best_agent (Agent): Global best agent.
function (Function): A function object.
height (np.array): Array of wave heights.
length (np.array): Array of wave lengths.
"""
# Iterates through all agents
for i, agent in enumerate(agents):
# Propagates a wave into a new temporary one (eq. 6)
wave = self._propagate_wave(agent, function, length[i])
# Checks if propagated wave is better than current one
if wave.fit < agent.fit:
# Also checks if propagated wave is better than global one
if wave.fit < best_agent.fit:
# Replaces the best agent with propagated wave
best_agent.position = copy.deepcopy(wave.position)
best_agent.fit = copy.deepcopy(wave.fit)
# Generates a `k` number of breaks
k = r.generate_integer_random_number(1, self.k_max + 1)
# Iterates through every possible break
for j in range(k):
# Breaks the propagated wave (eq. 10)
broken_wave = self._break_wave(wave, function, j)
# Checks if broken wave is better than global one
if broken_wave.fit < best_agent.fit:
# Replaces the best agent with broken wave
best_agent.position = copy.deepcopy(
broken_wave.position)
best_agent.fit = copy.deepcopy(broken_wave.fit)
# Replaces current agent's with propagated wave
agent.position = copy.deepcopy(wave.position)
agent.fit = copy.deepcopy(wave.fit)
# Sets its height to maximum height
height[i] = self.h_max
# If propagated wave is not better than current agent
else:
# Decreases its height by one
height[i] -= 1
# If its height reaches zero
if height[i] == 0:
# Refracts the wave and generates a new height and wave length (eq. 8-9)
height[i], length[i] = self._refract_wave(
agent, best_agent, function, length[i])
# Updates the wave length for all agents (eq. 7)
self._update_wave_length(agents, length)
def _mutate_agent(self, agent, alpha, beta, gamma):
"""Mutates a new agent based on pre-picked distinct agents (eq. 4).
Args:
agent (Agent): Current agent.
alpha (Agent): 1st picked agent.
beta (Agent): 2nd picked agent.
gamma (Agent): 3rd picked agent.
Returns:
A mutated agent.
"""
# Makes a deep copy of agent
a = copy.deepcopy(agent)
# Generates a random index for further comparison
R = r.generate_integer_random_number(0, agent.n_variables)
# For every decision variable
for j in range(a.n_variables):
# Generates a uniform random number
r1 = r.generate_uniform_random_number()
# If random number is smaller than crossover or `j` equals to the sampled index
if r1 < self.CR or j == R:
# Updates the mutated agent position
a.position[j] = alpha.position[j] + self.F * (beta.position[j] - gamma.position[j])
return a
def _update(self, agents, best_agent, function, velocity):
"""Method that wraps velocity and position updates over all agents and variables.
Args:
agents (list): List of agents.
best_agent (Agent): Global best agent.
function (Function): A function object.
velocity (np.array): Array of current velocities.
"""
# Iterate through all agents
for i, agent in enumerate(agents):
# Generates a random index based on the number of agents
index = r.generate_integer_random_number(0, len(agents))
# Updating velocity
velocity[i] = self._update_velocity(agent.position,
best_agent.position,
velocity[i], velocity[index],
i + 1)
# Clips the velocity values between (-v_max, v_max)
velocity = np.clip(velocity, -self.v_max, self.v_max)
# Updating agent's position
agent.position = self._update_position(agent.position, velocity[i])
# Checks agent limits
agent.clip_limits()
# Evaluates agent
agent.fit = function(agent.position)
def update(self, space: Space) -> None:
"""Wraps Crow Search Algorithm over all agents and variables.
Args:
space: Space containing agents and update-related information.
"""
# Iterates through every agent
for agent in space.agents:
# Generates uniform random numbers
r1 = r.generate_uniform_random_number()
r2 = r.generate_uniform_random_number()
# Generates a random integer (e.g. selects the crow)
j = r.generate_integer_random_number(high=len(space.agents))
# Checks if first random number is greater than awareness probability
if r1 >= self.AP:
# Updates agent's position (eq. 2)
agent.position += r2 * self.fl * (self.memory[j] -
agent.position)
# If random number is smaller than probability
else:
# Fills agent with new random positions
agent.fill_with_uniform()
def update(self, space: Space, function: Function) -> None:
"""Wraps EElectro-Search Algorithm over all agents and variables.
Args:
space: Space containing agents and update-related information.
function: A Function object that will be used as the objective function.
"""
# Iterates through all agents
for i, agent in enumerate(space.agents):
# Makes a deep copy of current agent
a = copy.deepcopy(agent)
# Creates a list of electrons
electrons = [copy.deepcopy(agent) for _ in range(self.n_electrons)]
# Iterates through all electrons
for electron in electrons:
# Generates a random number and the energy level
r1 = r.generate_uniform_random_number()
n = r.generate_integer_random_number(2, 6)
# Updates the electron's position (eq. 3)
electron.position += (2 * r1 - 1) * (1 - 1 / n**2) / self.D[i]
# Clips its bounds
electron.clip_by_bound()
# Re-evaluates the new position
electron.fit = function(electron.position)
# Sorts the electrons
electrons.sort(key=lambda x: x.fit)
# Generates both Rydberg constant and acceleration coefficient
# Original implementation is missing up an informative description
Re = r.generate_uniform_random_number()
Ac = r.generate_uniform_random_number()
# Updates the Orbital radius (eq. 4)
self.D[i] = (
electrons[0].position - space.best_agent.position
) + Re * (1 / space.best_agent.position**2 - 1 / a.position**2)
# Updates the temporary agent's position (eq. 5)
a.position += Ac * self.D[i]
# Checks agent's limits
a.clip_by_bound()
# Calculates the fitness for the temporary position
a.fit = function(a.position)
# If new fitness is better than agent's fitness
if a.fit < agent.fit:
# Copies its position and fitness to the agent
agent.position = copy.deepcopy(a.position)
agent.fit = copy.deepcopy(a.fit)
def _generate_new_harmony(self, agents: List[Agent]) -> Agent:
"""It generates a new harmony.
Args:
agents: List of agents.
Returns:
(Agent): A new agent (harmony) based on music generation process.
"""
# Mimics an agent position
a = copy.deepcopy(agents[0])
# For every decision variable
for j, (lb, ub) in enumerate(zip(a.lb, a.ub)):
# Generates an uniform random number
r1 = r.generate_uniform_random_number()
# Using the harmony memory
if r1 <= self.HMCR:
# Generates a random index
k = r.generate_integer_random_number(0, len(agents))
# Replaces the position with agent `k`
a.position[j] = agents[k].position[j]
# Generates a new uniform random number
r2 = r.generate_uniform_random_number()
# Checks if it needs a pitch adjusting
if r2 <= self.PAR:
# Generates a random index
z = r.generate_integer_random_number(0, a.n_variables)
# Updates harmony position
a.position[j] = agents[0].position[z]
# If harmony memory is not used
else:
# Generate a uniform random number
a.position[j] = r.generate_uniform_random_number(
lb, ub, size=a.n_dimensions
)
return a
def update(self, space: Space, function: Function) -> None:
"""Wraps Water Wave Optimization over all agents and variables.
Args:
space: Space containing agents and update-related information.
function: A function object.
"""
# Iterates through all agents
for i, agent in enumerate(space.agents):
# Propagates a wave into a new temporary one (eq. 6)
wave = self._propagate_wave(agent, function, i)
# Checks if propagated wave is better than current one
if wave.fit < agent.fit:
# Also checks if propagated wave is better than global one
if wave.fit < space.best_agent.fit:
# Replaces the best agent with propagated wave
space.best_agent.position = copy.deepcopy(wave.position)
space.best_agent.fit = copy.deepcopy(wave.fit)
# Generates a `k` number of breaks
k = r.generate_integer_random_number(1, self.k_max + 1)
# Iterates through every possible break
for j in range(k):
# Breaks the propagated wave (eq. 10)
broken_wave = self._break_wave(wave, function, j)
# Checks if broken wave is better than global one
if broken_wave.fit < space.best_agent.fit:
# Replaces the best agent with broken wave
space.best_agent.position = copy.deepcopy(
broken_wave.position)
space.best_agent.fit = copy.deepcopy(
broken_wave.fit)
# Replaces current agent's with propagated wave
agent.position = copy.deepcopy(wave.position)
agent.fit = copy.deepcopy(wave.fit)
# Sets its height to maximum height
self.height[i] = self.h_max
# If propagated wave is not better than current agent
else:
# Decreases its height by one
self.height[i] -= 1
# If its height reaches zero
if self.height[i] == 0:
# Refracts the wave and generates a new height and wave length (eq. 8-9)
self.height[i], self.length[i] = self._refract_wave(
agent, space.best_agent, function, i)
# Updates the wave length for all agents (eq. 7)
self._update_wave_length(space.agents)
def update(self, space: Space, function: Function) -> None:
"""Wraps Evolutionary Programming over all agents and variables.
Args:
space: Space containing agents and update-related information.
function: A Function object that will be used as the objective function.
"""
# Calculates the number of agents
n_agents = len(space.agents)
# Creates a list for the produced children
children = []
# Iterates through all agents
for i, agent in enumerate(space.agents):
# Mutates a parent and generates a new child
a = self._mutate_parent(agent, i, function)
# Updates the strategy
self._update_strategy(i, agent.lb, agent.ub)
# Appends the mutated agent to the children
children.append(a)
# Joins both populations
space.agents += children
# Number of individuals to be selected
n_individuals = int(n_agents * self.bout_size)
# Creates an empty array of wins
wins = np.zeros(len(space.agents))
# Iterates through all agents in the new population
for i, agent in enumerate(space.agents):
# Iterate through all tournament individuals
for _ in range(n_individuals):
# Gathers a random index
index = r.generate_integer_random_number(0, len(space.agents))
# If current agent's fitness is smaller than selected one
if agent.fit < space.agents[index].fit:
# Increases its winning by one
wins[i] += 1
# Sorts agents list based on its winnings
space.agents = [
agents
for _, agents in sorted(
zip(wins, space.agents), key=lambda pair: pair[0], reverse=True
)
]
# Gathers the best `n_agents`
space.agents = space.agents[:n_agents]
def kmeans(
x: np.ndarray,
n_clusters: Optional[int] = 1,
max_iterations: Optional[int] = 100,
tol: Optional[float] = 1e-4,
) -> np.ndarray:
"""Performs the K-Means clustering over the input data.
Args:
x: Input array with a shape equal to (n_samples, n_variables, n_dimensions).
n_clusters: Number of clusters.
max_iterations: Maximum number of clustering iterations.
tol: Tolerance value to stop the clustering.
Returns:
(np.ndarray): An array holding the assigned cluster per input sample.
"""
# Gathers the corresponding dimensions
n_samples, n_variables, n_dimensions = x.shape[0], x.shape[1], x.shape[2]
# Creates an array of centroids and labels
centroids = np.zeros((n_clusters, n_variables, n_dimensions))
labels = np.zeros(n_samples)
for i in range(n_clusters):
# Chooses a random sample to compose the centroid
idx = r.generate_integer_random_number(0, n_samples)
centroids[i] = x[idx]
for _ in range(max_iterations):
# Calculates the euclidean distance between samples and each centroid
dists = np.squeeze(np.array([np.linalg.norm(x - c, axis=1) for c in centroids]))
# Gathers the minimum distance as the cluster that conquers the sample
updated_labels = np.squeeze(np.array(np.argmin(dists, axis=0)))
# Calculates the difference ratio between old and new labels
ratio = np.sum(labels != updated_labels) / n_samples
if ratio <= tol:
break
# Updates the old labels with the new ones
labels = updated_labels
for i in range(n_clusters):
# Gathers the samples that belongs to current centroid
centroid_samples = x[labels == i]
# If there are samples that belongs to the centroid
if centroid_samples.shape[0] > 0:
# Updates the centroid position
centroids[i] = np.mean(centroid_samples, axis=0)
return labels
def _update(self, agents, n_agents, function, strategy):
"""Method that wraps evolution over all agents and variables.
Args:
agents (list): List of agents.
n_agents (int): Number of possible agents in the space.
function (Function): A Function object that will be used as the objective function.
strategy (np.array): An array of strategies.
Returns:
A new population with more fitted individuals.
"""
# Creating a list for the produced children
children = []
# Iterate through all agents
for i, agent in enumerate(agents):
# Mutates a parent and generates a new child
a = self._mutate_parent(agent, function, strategy[i])
# Updates the strategy
strategy[i] = self._update_strategy(strategy[i], agent.lb,
agent.ub)
# Appends the mutated agent to the children
children.append(a)
# Joins both populations
agents += children
# Number of individuals to be selected
n_individuals = int(n_agents * self.bout_size)
# Creates an empty array of wins
wins = np.zeros(len(agents))
# Iterate through all agents in the new population
for i, agent in enumerate(agents):
# Iterate through all tournament individuals
for _ in range(n_individuals):
# Gathers a random index
index = r.generate_integer_random_number(0, len(agents))
# If current agent's fitness is smaller than selected one
if agent.fit < agents[index].fit:
# Increases its winning by one
wins[i] += 1
# Sorts the agents list based on its winnings
agents = [
agents for _, agents in sorted(
zip(wins, agents), key=lambda pair: pair[0], reverse=True)
]
return agents[:n_agents]
def _update(self, agents, best_agent, fragrance):
"""Method that wraps global and local pollination updates over all agents and variables.
Args:
agents (list): List of agents.
best_agent (Agent): Global best agent.
fragrance (np.array): Array of fragrances.
"""
# Iterates through all agents
for i, agent in enumerate(agents):
# Calculates fragrance for current agent (eq. 1)
fragrance[i] = self.c * agent.fit**self.a
# Iterates through all agents
for i, agent in enumerate(agents):
# Generates a uniform random number
r1 = r.generate_uniform_random_number()
# If random number is smaller than switch probability
if r1 < self.p:
# Moves current agent towards the best one (eq. 2)
agent.position = self._best_movement(agent.position,
best_agent.position,
fragrance[i], r1)
# If random number is bigger than switch probability
else:
# Generates a `j` index
j = r.generate_integer_random_number(0, len(agents))
# Generates a `k` index
k = r.generate_integer_random_number(0,
len(agents),
exclude_value=j)
# Moves current agent using a local movement (eq. 3)
agent.position = self._local_movement(agent.position,
agents[j].position,
agents[k].position,
fragrance[i], r1)