Random numbers

Definition

Python can create random numbers. These are numbers chosen at random between two numbers and can be either integers or floating point numbers.

Easy example

import random
print(random.randint(1,10))
Show/Hide Output
3

Note

This program will produce a random integer between 1 and 10. It is likely to produce a different number the next time it is run.

Syntax

import random       #This imports the random number library so that we can use it in our program

random.randint(lowNumber, highNumber)

Examples

Example 1 - Find a random number between two numbers for a dice roll

import random

dice = random.randint(1,6)

print('The dice value is: ' + str(dice))
Show/Hide Output
The dice value is: 2

Example 2 - Find a random floating point number between 0.0 and 1.0

import random

randomFloat = random.random()

print(randomFloat)
Show/Hide Output
0.5850151855959205

Note

The output will be a floating point number between 0.0 and 1.0.

Example 3 - Use a random floating point number to toss a coin

import random

randomFloat = random.random()

if randomFloat > 0.5:
    print('heads')
else:
    print('tails')
Show/Hide Output
heads

Note

Randomly this program will print either heads or tails.

Example 4 - A random floating point number between 1 and 100

import random

randomFloat = random.random() * 100

print(randomFloat)
Show/Hide Output
11.525934431614193

Example 5 - A random percentage between 1 and 100 to two decimal places

import random

randomFloat = random.random() * 100

randomPercent = round(randomFloat, 2)

print(str(randomPercent) + '%')
Show/Hide Output
17.55%

Note

Randomly this will produce a percentage between 0.00% and 100.00%

Example 6 - A random choice from a list of options

import random

colors = ['red', 'green', 'yellow', 'blue', 'purple']

randomColor = random.choice(colors)

print(randomColor)
Show/Hide Output
purple

Note

An item from the list will be randomly picked.

Example 7 - Shuffle a list

import random

colours = ['red', 'green', 'yellow', 'blue', 'purple']

random.shuffle(colours)

print(colours)
Show/Hide Output
['blue', 'green', 'red', 'purple', 'yellow']

Note

The list will be randomly shuffled.

Key points

Warning

The random numbers shown below are not perfectly random, so shouldn’t be used for things like cryptography. But they are perfectly good enough for beginner-level programs and most other uses.