The random Module

The `random` Module
	Chapter 5. Advanced Expressions

The `random` Module

The random module is made available to your program with:

import random

The random module contains the following functions for working with simple distributions of random numbers. There are numerous other, more sophisticated distributions available, but some later exercises will only use these functions.

random.choice (sequence ) → value: chooses a random value from the sequence sequence. Example: random.choice( ['red', 'black', 'green'] ).
random.random → number: a random floating point number, r, 0 ≤ r < 1.0.
random.randrange ([start,] stop [,step] ) → integer: choose a random element from range(start, stop, step). Examples: randrange(6) returns a number, n, 0 ≤ n < 6. randrange(1,7) returns a number, n, 1 ≤ n < 7. randrange(10,100,5) returns a number, n, between 10 and 95 incremented by 5's, 10 ≤ 5k < 100.
random.uniform (a, b ) → number: a random floating point number, r, a ≤ r < b.

The randrange has two optional values, making it particularly flexible. Here's an example of some of the alternatives.

Example 5.1. demorandom.py

#!/usr/bin/env python
import random
# Simple Range 0 <= r < 6
print random.randrange(6), random.randrange(6)
# More complex range 1 <= r < 7
print random.randrange(1,7), random.randrange(1,7)
# Really complex range of even numbers between 2 and 36
print random.randrange(2,37,2)
# Odd numbers from 1 to 35
print random.randrange(1,36,2)

This demonstrates a number of ways of generating random numbers. It uses the basic random.randrange with a variety of different kinds of arguments.


The `math` Module		Advanced Expression Exercises