Possible misindexation in a004 (crossover function)

[LarsonVU]

In the function crossover, it uses the same index for both parents. This indicates that every second parent is instead duplicated, allowing evolution in this algorithm only by mutation, or am I missing something?

f crossover(population: Population) -> Population:
parents = [ind for ind in population if ind.tags.get("ps", False)]
for idx in range(0, len(parents), 2):
parent_i = parents[idx]
parent_j = parents[idx]

Namely, for the tournament selection of parents and survivors, this is indexed in the idx, idx+1 fashion.
Would love to know why this is different :)

[Deleuca]

I wanted to point out the same issue.

[Jacopo-DM]

Good catch, you are both correct, it was a bug! It wouldn't fail outright, but it would be just creating a copy of the single parent. Please fix it by [idx+1] on parent_j