Generate a random number which change every 24 hours

Question

Hi I make a app and want to know can we use random module to generate a random number which will change every 24 hours? Thanks for help.

Answer 1

You can reseed random by using a count of days since a fixed date:

from datetime import datetime
import random

d0 = datetime(2008, 8, 18)  # Pick an arbitrary date in the past
d1 = datetime.now()
delta = d1 - d0
print(delta.days)

random.seed(delta.days)
print(random.randint(1,10))

This will mean that print(random.randint(1,10)) will produce the same number anytime you run this today, but a likely different number tomorrow.

The delta section of this code was copied from this answer on stackoverflow.

Answer 2

Well, you can make use random and datetime module.

Here is the sample code:

import random, datetime

x = datetime.datetime.today().strftime("%Y:%m:%d")
random.seed(x)
r_int = random.randint(1, 100)
print(r_int)

Output:

73

Answer 3

Solutions based on reseeding the PRNG are effectively using the seed function as your random number generator rather than the PRNG state update algorithm. Because of this, there are no guarantees regarding the distributional properties of the result, whereas a good PRNG yields a sequence of values which pass numerous statistical tests for uniformity and lack of serial correlation.

The following solution wraps things up as a generator using yield, but the value to be yielded is only updated after the requisite period of time has passed, regardless of how many calls are made to the generator. If your app is intended to run for a multi-day extended period and you care about the distributional characteristics, I'd suggest something like this:

from datetime import datetime, timedelta
from random import randint # , seed
import time

def durable_randint(*, low = 1, high = 100, duration = timedelta(days = 1)):
    assert isinstance(duration, timedelta), 'duration must be a "timedelta"!'
    today = datetime.now()
    # seed(today.strftime("%Y:%m:%d"))
    last = today - 2 * duration
    while True:
        now = datetime.now()
        if now - last > duration:
            x = randint(low, high)
            last = datetime.now()
        yield x

if "__main__" == __name__:
    # The following is overriding the default duration of one day.
    # It will run for 45 seconds (15 iterations of 3 seconds),
    # changing the value generated every 10 seconds.
    gen = durable_randint(duration = timedelta(seconds = 10)) # lazy generator
    for _ in range(15):
        print(gen.__next__())   # next iteration of the generator
        time.sleep(3)

Uncommenting the lines involving seed will yield consistent results across multiple independent runs if the resolution is one day.