3 Greatest Methods to Generate a Random Quantity with a Fastened Quantity of Digits in Python – Finxter

Coding Problem

⚔️ Problem: Given an integer d representing the variety of digits. How you can create a random quantity with d digits in Python?

Listed below are three examples:

• my_random(2) generates 12
• my_random(3) generates 389
• my_random(10) generates 8943496710

I’ll talk about three attention-grabbing strategies to perform this simply in Python—my private favourite is Technique 2!

Shortest Answer with randint()

Let’s begin with a straightforward hand-coded statement:

The best method to create a random quantity with two digits is to make use of random‘s randint(10, 99), with three digits is randint(100,999), and with 4 digits is randint(1000,9999).

Right here’s the identical instance in Python code:

from random import randint

# Create random quantity with two digits (d=2):
print(randint(10, 99))

# Create random quantity with three digits (d=3):
print(randint(100, 999))

# Create random quantity with three digits (d=3):
print(randint(1000, 9999))

This resolution could be generalized by utilizing the one-liner random.randint(int('1'+'0'*(d-1)), int('9'*d)) that generates the beginning and finish values on the fly, primarily based on the variety of digits d.

I used easy string arithmetic to outline the beginning and finish index of the random vary:

• int('1'+'0'*(d-1)) creates the beginning index comparable to 100 for d=3.
• int('9'*d)) creates the top index that’s included in randint() comparable to 999 for d=3.

Right here’s the essential Python instance:

import random

def my_random(d):
    ''' Generates a random quantity with d digits '''
    return random.randint(int('1'+'0'*(d-1)), int('9'*d))


for i in vary(1, 10):
    print(my_random(i))

'''
Output:
8
82
296
5909
90957
227691
1348638
61368798
160959002
'''

Cleanest Answer with randrange()

The cleanest resolution is predicated on the randrange() perform from the random module that takes the beginning and finish index as enter and generates a random quantity in between.

In contrast to randint(), the top index is excluded in randrange(), so we’ve a neater method to assemble our vary for the d-digit random quantity downside: random.randrange(10**(d-1), 10**d).

Right here’s an instance:

import random

def my_random(d):
    ''' Generates a random quantity with d digits '''
    return random.randrange(10**(d-1), 10**d)


for i in vary(1, 10):
    print(my_random(i))

'''
Output:
7
64
872
2440
39255
979369
6897920
83589118
707920991
'''

An Iterative Answer Aggregating Outputs of Single-Digit Random Operate Calls

It’s also possible to use a one-liner to repeatedly execute the random.randint() perform for every digit. To mix the digits, you convert every digit to a string, cross them into the string.be part of() perform to get one string with d characters, and convert this string again to an integer:

int(''.be part of(str(random.randint(0,9)) for _ in vary(d)))

Right here’s this precise method in a Python code snippet:

import random

def my_random(d):
    ''' Generates a random quantity with d digits '''
    return int(''.be part of(str(random.randint(0,9)) for _ in vary(d)))


for i in vary(1, 10):
    print(my_random(i))

'''
Output:
6
92
135
156
95865
409722
349673
31144072
439469934
'''

Abstract

Thanks for studying by means of the entire article—I hope you bought some worth out of it.

Right here’s once more a abstract of greatest generate a random quantity with d digits in Python:

1. random.randint(int('1'+'0'*(d-1)), int('9'*d))
2. random.randrange(10**(d-1), 10**d)
3. int(''.be part of(str(random.randint(0,9)) for _ in vary(d)))

Personally, I like Technique 2 probably the most as a result of it’s quick, concise, and really environment friendly!

Whereas working as a researcher in distributed methods, Dr. Christian Mayer discovered his love for educating pc science college students.

To assist college students attain increased ranges of Python success, he based the programming training web site Finxter.com. He’s writer of the favored programming guide Python One-Liners (NoStarch 2020), coauthor of the Espresso Break Python sequence of self-published books, pc science fanatic, freelancer, and proprietor of one of many high 10 largest Python blogs worldwide.

His passions are writing, studying, and coding. However his best ardour is to serve aspiring coders by means of Finxter and assist them to spice up their expertise. You may be part of his free electronic mail academy right here.