l = range(int(1E9))

[Marko Rauhamaa]

BartC <bc at freeuk.com>:

> (I tried an empty loop counting to 1 billion in Python 2.x, using 'for
> i in range'. It ran out of memory. Counting to 100 million instead, it
> worked, but still used a massive 1.5GB RAM while doing so (and took 6
> seconds to count to 100M, not too bad for Python)
>
> Outside Python, it might typically take a few seconds to count to 1
> billion, and would use virtually no memory.
>
> Why would anyone want to loop over all those numbers instead of
> iterating over actual data? For any number of reasons. Counting how
> many happy numbers are in that range for one!)

You're doing it wrong. Here's the Pythonic way to iterate over a billion
numbers:

    def loop(i):
        if i < 1000000000:
            do_stuff(i)
            keep_iterating(i + 1)

    loop(0)


Marko