random.randint(2, 12) returns same results every time it's run in Python

Question

I have a script that generates 10 random numbers between 2 and 12:

repetition = 10
while repetition > 0:
    print(random.randint(2,12))
    repetition = repetition - 1

When this code is executed 10 random numbers are generated, but each time I execute the code the same 10 random numbers are generated. This happens even if I run the code on a different computer!

Answer 1

The first thing that you should understand is that computer generated random numbers are not really random. To generate a pseudo-random number, the computer uses a function that generates a number based on a previous value (more details in https://en.wikipedia.org/wiki/Random_number_generation). The sequence of pseudo-random numbers depends on the first value passed to this function, known as seed.

By default in the Random class' constructor (__init__), used by Python's random module, the seed is defined by the operating system. This is usually based on the current system time. If you defined your own seed using the function random.seed your results will be deterministic. You will always get the same values in this case.