# urandom – Pseudo-random numbers¶

This module implements pseudo-random number generators.

All functions in this module should be used with positional arguments. Keyword arguments are not supported.

Basic random numbers

randint(a, b) int

Gets a random integer $$N$$ satisfying $$a \leq N \leq b$$.

Parameters
• a (int) – Lowest value. This value is included in the range.

• b (int) – Highest value. This value is included in the range.

Returns

The random integer.

random()

Gets a random value $$x$$ satisfying $$0 \leq x < 1$$.

Returns

The random value.

Random numbers from a range

getrandbits(k) int

Gets a random integer $$N$$ satisfying $$0 \leq N < 2^{\text{bits}}$$.

Parameters

k (int) – How many bits to use for the result.

randrange(stop) int
randrange(start, stop) int
randrange(start, stop, step) int

Returns a randomly selected element from range(start, stop, step).

For example, randrange(1, 7, 2) returns random numbers from 1 up to (but excluding) 7, in increments of 2. In other words, it returns 1, 3, or 5.

Parameters
• start (int) – Lowest value. Defaults to 0 if only one argument is given.

• stop (int) – Highest value. This value is not included in the range.

• step (int) – Increment between values. Defaults to 1 if only one or two arguments are given.

Returns

The random number.

uniform(a, b)

Gets a random floating point value $$x$$ satisfying $$a \leq x \leq b$$.

Parameters
• a (float) – Lowest value.

• b (float) – Highest value.

Returns

The random value.

Random elements from a sequence

choice(sequence) Any

Gets a random element from a sequence such as a tuple or list.

Parameters

sequence – Sequence from which to select a random element.

Returns

The randomly selected element.

Raises

IndexError – If the sequence is empty.

Updating the random seed

seed(value=None)

Initializes the random number generator.

This gets called when the module is imported, so normally you do not need to call this.

Parameters

value – Seed value. When using None, the system timer will be used.