[robinhouston]

That’s funny. I’ve always done it the forwards way. I didn’t even realise that wasn’t the usual way.

I suppose one of the benefits of having a poor memory is that one sometimes improves things in the course of rederiving them from an imperfect recollection.

[furyofantares]

Same, I've implemented it a number of times and always done it forward, and can't recall ever seeing it backwards. I've looked at the wikipedia page for it more than once too, which, as the article mentions, shows it backwards.

Maybe it's because it's so easy to prove to yourself that Fisher-Yates generates every possible combination with the same probability[1], and so forwards or backwards just doesn't register as relevant.

[1]This of course makes the a hefty assumption about the source of random numbers which is not true in the vast majority of cases where the algorithm is put into practice as PRNGs are typically what's used. For example if you use a PRNG with a 64 bit seed then you cannot possibly reach the vast majority of states for a 52 card deck; you need 226 bits of state for that to even be possible. And of course even if you are shuffling with fewer combinations than the PRNG state can represent, you will always have some (extremely slight) bias if the state does not express an integer multiple of the number of permutations of your array size.

[furyofantares]

On further inspection the one I'm used to is forward-mirrored, which is exactly the same as backward but the opposite direction.