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This tutorial demonstrates methods to generate and output any random prime number in Python.

Prime numbers are very useful constants used in programming, especially in cryptography. The use of prime numbers is crucial in encryption and hashing as they can be used to encrypt and hash sensitive data and prevent them from being decrypted at will.

Create a function to generate random prime numbers in a given range

A prime number has only 2 factors (a factor is a number that can be divided by another number and still leave a whole number). A prime number can only be divided by 1 and itself.

It is technically impossible to generate a random prime number from 0 to infinity, as it would require a lot of processing power to keep it that large.

For this reason, we need to include a range of numbers as parameters to collect prime numbers within the set range.

The first thing to do is to create a function to collect all the prime numbers in a given range into a list. For this function, loop over all the numbers in the range and check if only 1 and itself are divisible.

def primesInRange(x, y):
    prime_list = []
    for n in range(x, y):
        isPrime = True

        for num in range(2, n):
            if n % num == 0:
                isPrime = False

        if isPrime:
            prime_list.append(n)

    return prime_list


print(primesInRange(100, 250))

The output will print all the prime numbers from the given range 100 to 250.

Output:

[101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241]

The next step is primesInRange()to generate a random number within the range of prime numbers returned by the function.

Under the Python randommodule, it has a choice()function called which selects a random element from a given iterable or sequence.

Given the function implemented above primesInRange(), capture the return value using a list variable and use random.choice()to select a random prime number from the list. choice()Before using the function, don’t forget to import randomthe module.

import random

prime_list = primesInRange(100, 250)
randomPrime = random.choice(prime_list)

print("Generated random prime number: ", randomPrime)

Sample random output:

Generated random prime number:  191

Here is the full source code for this solution.

import random


def primesInRange(x, y):
    prime_list = []
    for n in range(x, y):
        isPrime = True

        for num in range(2, n):
            if n % num == 0:
                isPrime = False

        if isPrime:
            prime_list.append(n)
    return prime_list


prime_list = primesInRange(100, 250)
randomPrime = random.choice(prime_list)

print("Generated random prime number: ", randomPrime)