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Small and efficient implementation of the Differential Evolution algorithm using the rand/1/bin schema
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import numpy as np | |
def de(fobj, bounds, mut=0.8, crossp=0.7, popsize=20, its=1000): | |
dimensions = len(bounds) | |
pop = np.random.rand(popsize, dimensions) | |
min_b, max_b = np.asarray(bounds).T | |
diff = np.fabs(min_b - max_b) | |
pop_denorm = min_b + pop * diff | |
fitness = np.asarray([fobj(ind) for ind in pop_denorm]) | |
best_idx = np.argmin(fitness) | |
best = pop_denorm[best_idx] | |
for i in range(its): | |
for j in range(popsize): | |
idxs = [idx for idx in range(popsize) if idx != j] | |
a, b, c = pop[np.random.choice(idxs, 3, replace = False)] | |
mutant = np.clip(a + mut * (b - c), 0, 1) | |
cross_points = np.random.rand(dimensions) < crossp | |
if not np.any(cross_points): | |
cross_points[np.random.randint(0, dimensions)] = True | |
trial = np.where(cross_points, mutant, pop[j]) | |
trial_denorm = min_b + trial * diff | |
f = fobj(trial_denorm) | |
if f < fitness[j]: | |
fitness[j] = f | |
pop[j] = trial | |
if f < fitness[best_idx]: | |
best_idx = j | |
best = trial_denorm | |
yield best, fitness[best_idx] |
Python does not use the ^ operator, but ** instead: (1-x)**2 + 100...
Hi Pablo, I have the same problem: cannot import name 'problem' from 'yabox.problems'
I installed yabox in my machine and doesn't work.
Hi how should I change the code to get best/1/bin
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hi Pablo, how I fit the follow function in your code? fobj = lambda x: sum(((1-x) ^2)+ 100*(((x+1) - x^2)^2)/len(x-1)
all the bounds i put give me a SyntaxError: invalid syntax