Python: Random System time seed

Question

In python, and assuming I’m on a system which has a random seed generator, how do I get random.seed() to use system time instead? (As if /dev/urandom did not exist)

Asked By: Academiphile

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Source

Answer 1

you can do

import random
import time
random.seed(time.time())

Answered By: Elisha

Answer 2

import random
from datetime import datetime
random.seed(datetime.now().timestamp())

Answered By: Quint

Answer 3

Do you know this library: PyRandLib? See:

https://schmouk.github.io/PyRandLib/ to easily download archives versions, and
https://github.com/schmouk/PyRandLib to get access to the code.

This library contains many of the best-in-class pseudo-random numbers generators while acting exactly as does the Python “built-in” library random (just un-zip or un-tar the downloaded archive in the ‘Lib/site-packages/’ sub-directory of your Python directory).

From the code, and from module ‘fastrand32.py’, you’ll get a quite more sophisticated way to feed random with a shuffled version of current time. For your purpose, this would become:

import time
import random

t = int( time.time() * 1000.0 )
random.seed( ((t & 0xff000000) >> 24) +
             ((t & 0x00ff0000) >>  8) +
             ((t & 0x0000ff00) <<  8) +
             ((t & 0x000000ff) << 24)   )

This provides a main advantage: for very short periods of time, the initial seeds for feeding the pseudo-random generator will be hugely different between two successive calls.

Answered By: Schmouk

Answer 4

As of day, Dec 2021, the better option is to use methods from "secrets" module. You don’t need to set such seed anymore.

Sample Code:

import secrets
print (secrets.randbelow(1_000_000_000))

Answered By: M2014

Python: Random System time seed

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