Issues with push method on array

Question

I have a storage array and I able to use push method. But, in another part of my code, I have a memory array and I can't do that. What's the reason? Doesn't exist push method in memory arrays?

        Individual[] memory newPop = new Individual[](popSize);
        for(uint i = 0; i < popSize; i++){
            uint index1;
            uint index2;
            (index1, index2) = getIndex();
            Individual newIndiv = crossover(index1, index2);
            newPop.push(newIndiv);
        }

And the error:

Answer 1

Keywords push and pop are applicable only for dynamic arrays.

Dynamic arrays can be declared only in storage (i.e., in global scope) AND with no predefined size.

For example: uint256[] public arr.

Aside from that, you've already allocated the local array newPop to the desired size, so why would you want to hypothetically use push and increase that size?

You should simply change this:

newPop.push(newIndiv);

To this:

newPop[i] = newIndiv;