Documentation

See PY 3 documentation for random module in the standard library.

See Examples and Recipes in those docs.

General

import random


random.random()

Or

from random import random


random()

Floats

Random float: 0.0 <= x < 1.0

>>> random.random()
0.37444887175646646

Random float: 2.5 <= x < 10.0

>>> random.uniform(2.5, 10.0)
3.1800146073117523

Interval between arrivals averaging 5 seconds

>>> random.expovariate(1 / 5)
5.148957571865031

Integers

Integer from 0 to 9 inclusive

>>> random.randrange(10)
7

Even integer from 0 to 100 inclusive

>>> random.randrange(0, 101, 2)
26

Selection

choice function

Single random element from a sequence.

>>> random.choice(['win', 'lose', 'draw'])
'lose'

>>> random.choice('abcdef')
'f'

choices function

Similar to choice but accepts an optional count to return.

>>> random.choices(['win', 'lose', 'draw'])
['draw']

>>> random.choices(['win', 'lose', 'draw'], k=2)
['draw', 'lose']
>>> random.choices('abcdef', k=10)
['e', 'c', 'a', 'e', 'e', 'd', 'e', 'a', 'c', 'b']

sample function

Four samples without replacement.

>>> random.sample([10, 20, 30, 40, 50], k=4)
[40, 10, 50, 30]

Shuffle

Shuffle a list.

>>> deck = 'ace two three four'.split()
>>> random.shuffle(deck)
>>> deck
['four', 'two', 'ace', 'three']

Strings

Generate random text.

See String Constants page for more info on the string module’s values.

Note use of .choices to get multiple values.

import random
import string


chars = string.ascii_lowercase

length = 20

''.join(random.choices(chars, k=length))
# 'sibuudijstpmozrmrfzp'

Or use .choice for a more verbose and possibly inefficient way.

''.join(random.choice(letters) for _ in range(k))
# 'ohzeasftnbkvinijtkud'

Passwords

The docs recommend the secrets module.

The secrets module is used for generating cryptographically strong random numbers suitable for managing data such as passwords, account authentication, security tokens, and related secrets.

In particular, secrets should be used in preference to the default pseudo-random number generator in the random module, which is designed for modelling and simulation, not security or cryptography.

>>> chars = string.ascii_uppercase + string.digits

>>> ''.join(random.SystemRandom().choice(chars) for _ in range(length))
'xgfzjbzgkogbrqvakutd'