Maximal Length of List to Shuffle with Python random.shuffle?

Question

I have a list which I shuffle with the Python built in shuffle function (random.shuffle)

However, the Python reference states:

No

Answer 1

What they mean is that permutations on n objects (noted n!) grows absurdly high very fast.

Basically n! = n x n-1 x ... x 1; for example, 5! = 5 x 4 x 3 x 2 x 1 = 120 which means there are 120 possible ways of shuffling a 5-items list.

On the same Python page documentation they give 2^19937-1 as the period, which is 4.something × 10^6001 or something. Based on the Wikipedia page on factorials, I guess 2000! should be around that. (Sorry, I didn't find the exact figure.)

So basically there are so many possible permutations the shuffle will take from that there's probably no real reason to worry about those it won't.

But if it really is an issue (pesky customer asking for a guarantee of randomness perhaps?), you could also offload the task to some third-party; see http://www.random.org/ for example.