Python Random Module

Python Random module is an in-built module of Python that is used to generate random numbers in Python. These are pseudo-random numbers means they are not truly random. This module can be used to perform random actions such as generating random numbers, printing random a value for a list or string, etc.

List of all the functions  Python Random Module

Function Name	Description
seed()	Initialize the random number generator
getstate()	Returns an object with the current internal state of the random number generator
setstate()	Used to restore the state of the random number generator back to the specified state
getrandbits()	Return an integer with a specified number of bits
randrange()	Returns a random number within the range
randint()	Returns a random integer within the range
choice()	Returns a random item from a list, tuple, or string
choices()	Returns multiple random elements from the list with replacement
sample()	Returns a particular length list of items chosen from the sequence
random()	Generate random floating numbers
uniform()	Return a random floating number between two numbers both inclusive
triangular()	Return a random floating point number within a range with a bias towards one extreme
betavariate()	Return a random floating point number with beta distribution
expovariate()	Return a random floating point number with exponential distribution
gammavariate()	Return a random floating point number with a gamma distribution
gauss()	Return a random floating point number with Gaussian distribution
lognormvariate()	Return a random floating point number with a log-normal distribution
normalvariate()	Return a random floating point number with normal distribution
vonmisesvariate()	Return a random floating point number with von Mises distribution or circular normal distribution
paretovariate()	Return a random floating point number with a Pareto distribution
weibullvariate()	Return a random floating point number with Weibull distribution

Random in Python Examples

Let’s discuss some common operations performed by this module.

Example: Printing a random value from a list in Python.

This code uses the random module to select a random element from the list list1 using the random.choice() function. It prints a random element from the list, demonstrating how to pick a random item from a sequence in Python.

Python3

import random
list1 = [1, 2, 3, 4, 5, 6]
print(random.choice(list1))

Output:

2

Example: Creating random numbers with Python seed() in Python.

As stated above random module creates pseudo-random numbers. Random numbers depend on the seeding value. For example, if the seeding value is 5 then the output of the below program will always be the same. Therefore, it must not be used for encryption.

The code sets the random number generator’s seed to 5 using random.seed(5), ensuring reproducibility. It then prints two random floating-point numbers between 0 and 1 using random.random(). The seed makes these numbers the same every time you run the code with a seed of 5, providing consistency in the generated random values.

Python3

import random
random.seed(5)
print(random.random())
print(random.random())

Output:

0.6229016948897019
0.7417869892607294

Generate Random Numbers in Python

random.randint() method is used to generate random integers between the given range.

Syntax: randint(start, end)

Example: Creating random integers

This code uses the ‘random' module to generate random integers within specific ranges. It first generates a random integer between 5 and 15 (inclusive) and then between -10 and -2 (inclusive). The generated integers are printed with appropriate formatting.

Python3

import random
r1 = random.randint(5, 15)
print("Random number between 5 and 15 is % s" % (r1))
r2 = random.randint(-10, -2)
print("Random number between -10 and -2 is % d" % (r2))

Output:

Random number between 5 and 15 is 7
Random number between -10 and -2 is -9

Generate Random Float numbers in Python

A random.random() method is used to generate random floats between 0.0 to 1.

Syntax: random.random()

Example:

In this code, we are using the random function from the ‘random' module in Python. It prints a random floating-point number between 0 and 1 when you call random().

Python3

from random import random
print(random())

Output:

0.3717933555623072

Randomly Select Elements from a List in Python

Random sampling from a list in Python (random.choice, and sample)

Example 1:  Python random.choice() function is used to return a random item from a list, tuple, or string.

The code uses the random.choice() function from the random module to randomly select elements from different data types. It demonstrates selecting a random element from a list, a string, and a tuple. The chosen elements will vary each time you run the code, making it useful for random selection from various data structures.

Python3

import random
list1 = [1, 2, 3, 4, 5, 6]
print(random.choice(list1))
string = "geeks"
print(random.choice(string))
tuple1 = (1, 2, 3, 4, 5)
print(random.choice(tuple1))

Output:

2
k
5

Example 2:  Python random.sample() function is used to return a random item from a list, tuple, or string.

Syntax: random.sample(sequence, length)

This code utilizes the sample function from the ‘random' module to obtain random samples from various data types. It selects three random elements without replacement from a list, a tuple, and a string, demonstrating its versatility in generating distinct random samples. With each execution, the selected elements will differ, providing random subsets from the input data structures.

Python3

from random import sample
list1 = [1, 2, 3, 4, 5]

print(sample(list1,3))
list2 = (4, 5, 6, 7, 8)

print(sample(list2,3))
list3 = "45678"

print(sample(list3,3))

Output:

[1, 5, 4]
[8, 5, 6]
['7', '4', '5']

Shuffle List in Python

A random.shuffle() method is used to shuffle a sequence (list). Shuffling means changing the position of the elements of the sequence. Here, the shuffling operation is inplace.

Syntax: random.shuffle(sequence, function)

Example: Shuffling a List

This code uses the random.shuffle() function from the ‘random' module to shuffle the elements of a list named ‘sample_list'. It first prints the original order of the list, then shuffles it twice. The second shuffle creates a new random order, and the list’s content is displayed after each shuffle. This demonstrates how the elements are rearranged randomly in the list with each shuffle operation.

Python3

import random
sample_list = [1, 2, 3, 4, 5]

print("Original list : ")
print(sample_list)
random.shuffle(sample_list)
print("\nAfter the first shuffle : ")
print(sample_list)
random.shuffle(sample_list)
print("\nAfter the second shuffle : ")
print(sample_list)

Output:

Original list : 
[1, 2, 3, 4, 5]
After the first shuffle : 
[4, 3, 5, 2, 1]
After the second shuffle : 
[1, 3, 4, 5, 2]