Division by 0 if fitness_sum is 0

Hi,

I encountered a case where, if I'm using roulette wheel selection or stochastic universal selection and if the fitness sum is 0, there will be a division by 0. I know that probably it's very little probability to encounter such a case, but my suggestion would be to instead of having probs = fitness / fitness_sum
to have:

if fitness_sum !=0:
   probs = fitness / fitness_sum
else:
   probs = 0

or instead of probs=0, to divide fitness by a very large number.

Best Regards!

[ahmedfgad]

Hi @ardeleanasm,

Thank you!

Note that probs should be a 1D NumPy array with number of elements equal to the number of solutions. So, we cannot assign it an integer probs = 0.

Assuming that fitness_num=0, then all the values in props will be NaN. By following the code, then proceeding with elements of probs set to NaN or setting them to zeros causes a logical error.

I think a proper solution is to raise an exception if this situation happened.

Thank you! You did a great job with this package. I like a lot to work with it. Simple to use, well documented and very good implementation.

[ahmedfgad]

Thanks @ardeleanasm! If you found any issues or suggestions, please do not hesitate to report them.