`random` — generate random numbers¶

This module implements a pseudo-random number generator (PRNG). The PRNG is a 32-bit Yasmarang-style LCG; on first import it draws one 32-bit seed from the same hardware source os.urandom() uses, and every subsequent number is a deterministic function of that seed.

Warning

The output is not cryptographically secure – the algorithm is predictable from a short output sequence, and the initial seed carries only 32 bits of entropy. For keying material, session tokens, password salts, or any other security-sensitive use, call os.urandom() instead.

Note

The following notation is used for intervals:

() are open interval brackets and do not include their endpoints. For example, (0, 1) means greater than 0 and less than 1. In set notation: (0, 1) = {x | 0 < x < 1}.
[] are closed interval brackets which include all their limit points. For example, [0, 1] means greater than or equal to 0 and less than or equal to 1. In set notation: [0, 1] = {x | 0 <= x <= 1}.

Functions for integers¶

random.getrandbits(n: int) → int¶: Return an integer with n random bits (0 <= n <= 32).

random.randint(a: int, b: int) → int¶: Return a random integer in the range [a, b].

random.randrange(start: int, stop: int | None = None, step: int = 1) → int¶: The first form returns a random integer from the range [0, stop). The second form returns a random integer from the range [start, stop). The third form returns a random integer from the range [start, stop) in steps of step. For instance, calling randrange(1, 10, 2) will return odd numbers between 1 and 9 inclusive.

Functions for floats¶

random.random() → float¶: Return a random floating point number in the range [0.0, 1.0).

random.uniform(a: float, b: float) → float¶: Return a random floating point number N such that a <= N <= b for a <= b, and b <= N <= a for b < a.

Other Functions¶

random.seed(n: int | None = None, /) → None¶: Initialise the random number generator module with the seed n, which should be an integer. When no argument (or None) is passed in, the PRNG is re-seeded from the same port-specific source os.urandom() uses.

random.choice(sequence: Any) → Any¶: Chooses and returns one item at random from sequence (tuple, list or any object that supports the subscript operation).