What's a good shuffle percentage?

I'm basically new to coding for random results, but did some reading and tested out the javascript version of the Fisher-Yates algorithm (as seen on wikipedia), with an ordered list.

I ended up adding code to make sure the array was shuffled differently than its initial order, and also calculated the percentage of how many objects were shuffled to a different position by the algorithm.

So I'm wondering what might be considered a good result. Kind of a generic question. If I shuffled a deck of cards, what would be the least acceptable amount of shuffle? Right now I have mine coded to repeat the开发者_开发问答 algorithm if it comes out less than 25 percent shuffled.

What do you think?

Zero. You can make any number of checks you like to make it feel more random, but even the check for the same order makes your algorithm flawed.

If your shuffle algorithm is correctly implemented and produces a truly random shuffle (modulo your PRNG's randomness, or lack thereof), I wouldn't reshuffle at all. In particular, the fact that you don't accept random configurations that are 25+% similar to your original configuration tells an adversary that they can expect not to see any of those configurations after your shuffling completes.

Thanks for the feedback. All of your answers were relevant.

I'm adding this answer since my notion of shuffling went from random to non random, and now I'm using a hybrid of the two.

With the perfect in-shuffle I can generate multiple lists in different orders (which modulate off the number of items). However, when the number of items is odd, the last number does not get shuffled. So I decided to randomize its position in the shuffled list.

In the process of figuring that out, I made a table generator which displays all the lists possible given a number of items. It's pretty interesting. For example, the number 52 generates 52 columns, while the number 51 only generates 8 columns.