Why do we need infinite Python arrays?

Question

css

I don't really understand the meaning of infinite arrays in Python. It would be nice if you could just refer to a specific element, and it would be calculated, and the result would be automatically cached and all that. So no, after all, you need to iterate over the elements with a for-in loop. It is not clear whether there is any profit from this compared to a function that returns the desired element instead of an infinite array?

def factorial():
    i = 1
    k = 1
    while True:
        yield k
        k = k * i
        i += 1

factorial()[5] # так нельзя

for i in factorial():
    ...
    if ...: break # так можно, но зачем?

Answer 1

vertical-align: middle

Answer 2

Like this: https://jsfiddle.net/tg1pvsoz/1/

Answer 3

It's not an array, it's a generator. Its similarity with an array is only that both are iterable.
Why generators are needed is perfectly explained with examples here www.diveintopython3.net/generators.html

Answer 4

The array (list) is a full barrel (of water).
A generator is a pipe from which water flows.
A barrel will not always replace a pipe.