Menu
I have a list with around 3900 elements that I need to randomly permute to produce a statistical distribution. I looked around and found this Maximal Length of List to Shuffle with Python random.shuffle that explains that the period of the PRNG in Python is 2**19937-1, which leads to a list with a maximum length of 2080 before it becomes impossible to generate all possible permutations. I am only producing 300-1000 permutations of the list so it unlikely that I will be producing duplicate permutations, however, since this is producing a statistical distribution I would like to have all possible permutations as potential samples.
224
Python Random shuffle() Method The shuffle() method takes a sequence, like a list, and reorganize the order of the items. Note: This method changes the original list, it does not return a new list.
The random. sample() function returns the random list with the sample size you passed to it. For example, sample(myList, 3) will return a list of 3 random items from a list. If we pass the sample size the same as the original list's size, it will return us the new shuffled list.
There are longer-period PRNGs than MT, but they are hard to find.
To get all 3090! combinations, you need 40,905 bits of entropy. That's about 5kb. You should be able to grab a chunk of bytes that size from someplace like random.org many times with no problem. To get precisely balanced, you'll have to add some and do rejection sampling. I.e., grab 12 bits at a time (0..4095), and reject numbers higher than your current loop index. That might inflate the number of bits needed, but probably not beyond 8kb.
197
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
