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rocreguant/roulette_wheel_selection_minimization.py

Created March 14, 2021 10:26
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Roulette wheel selection example in python for minimisation problems
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roulette_wheel_selection_minimization.py
import numpy as np
def roulette_wheel_selection(population):
# Computes the totallity of the population fitness
population_fitness = sum([chromosome.fitness for chromosome in population])
# Computes for each chromosome the probability
chromosome_probabilities = [chromosome.fitness/population_fitness for chromosome in population]
# Making the probabilities for a minimization problem
chromosome_probabilities = 1 - np.array(chromosome_probabilities)
# Selects one chromosome based on the computed probabilities
return np.random.choice(population p=chromosome_probabilities)
@mufassir-khan
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This function is throwing errors for me. chromosome.fitness.values[0] in place of chromosome.fitness is working.

Also, sum of probabilities is not one. Hence, this is not working.

@rocreguant
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This function is throwing errors for me. chromosome.fitness.values[0] in place of chromosome.fitness is working.

Also, sum of probabilities is not one. Hence, this is not working.

Maybe you would be interested in checking the full code and adapt it to yours.
https://github.com/rocreguant/personal_blog/tree/main/Genetic_Algorithm_Python_Example
If you have more questions I'm glad to answer them ;)

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