How do I initialize a list with x positions in Python?

Question

I want to create in the list x empty positions before filling, as I do?

Answer 1

To solve your problem it will take nothing more than a multiplication... Just as you can create a print() as follows:

print('-' * 10)

Upshot: ----------
You can create a list using the same technique.
This way the code would be like this:

lista = [None] * 50 #o valor 50 pode ser trocado por qualquer um

This will create a lista with 50 positions all filled with the value None which may subsequently be replaced by any other desired value.
To be sure of the result do the following tests:

print(len(lista)) #ira mostrar o tamanho da lista criada. No caso aqui vai aparecer 50.
print(lista) #Mostra toda a lista com os seus valores, se você contar irá ver que possui 50 elementos.