Python Random Number Generator

Both functions are in the standard library - nothing to install. randint includes both ends; randrange excludes the stop value, like range().

import random

random.randint(1, 10)      # 1..10, both ends included
random.randrange(0, 10)    # 0..9, stop is excluded
random.randrange(0, 100, 5)  # 0, 5, 10 ... 95

random() returns a float in [0.0, 1.0); uniform(a, b) scales it to your range.

import random

random.random()          # 0.0 <= x < 1.0
random.uniform(1.5, 4.5)  # float between 1.5 and 4.5

choice picks one item, sample picks several without repeats, shuffle reorders a list in place.

import random

items = ["red", "green", "blue", "yellow"]
random.choice(items)       # one item
random.sample(items, 2)    # two different items
random.shuffle(items)      # shuffles the list in place, returns None

The random module is a Mersenne Twister: fast and reproducible, but predictable. For passwords, tokens, invite codes or prize draws use secrets, which reads from the operating system CSPRNG.

import secrets

secrets.randbelow(10) + 1   # 1..10
secrets.choice(["a", "b"])  # secure pick
secrets.token_hex(16)       # 32 hex characters
secrets.token_urlsafe(16)   # URL-safe token
secrets.SystemRandom().shuffle(items)  # secure shuffle

Naming your own file random.py shadows the module, so import random loads your file and random.randint fails with an AttributeError - rename the file and delete __pycache__. Use random.seed(42) only when you want the same sequence every run (tests, simulations).

import random

random.seed(42)       # reproducible sequence
print(random.randint(1, 6))