How do I randomly pick between 2 numbers in python with exceptions?

Question

My problem is very simple. I'm trying to pick between 2 random numbers in python but not from consecutive numbers like here .

For example: between 1 and 3, 2 not included.

Answer 1

get two random numbers, check if their difference is not 1 and print them out

import random

def get_two_random_numbers():
    num1, num2 = random.sample(range(1, 100), 2)
    return num1, num2


rand_num1, rand_num2 = get_two_random_numbers()

while (abs(rand_num1-rand_num2 == 1)):
    rand_num1, rand_num2 = get_two_random_numbers()

print(rand_num1)
print(rand_num2)

Answer 2

The easiest solution to this is probably random.choice.

import random

number = random.choice((1, 3))

Answer 3

A different approach: instead of getting numbers and rejecting them we could let Python do the job for us. This may be useful if we need to exclude many numbers (or if we want to get more than one value at a time, of course)

from random import choices

def rand_except(start, stop, exclude, k):
    weights = [1 for _ in range(start,stop)]
    for excl in exclude:
        weights[excl-start] = 0
    return choices(range(start,stop), weights=weights, k=k)

Answer 4

Here is an approach:

import random

pool = list(range(1, 3+1))
pool.remove(2)

out = random.choice(pool)

generic approach:

def randint_except(start, stop, exclude=None):
    pool = list(range(start, stop+1))
    if exclude is not None:
        if isinstance(exclude, int):
            pool.remove(exclude)
        else:
            S = set(exclude)
            pool = [x for x in pool if x not in S]
    return random.choice(pool)

randint_except(1, 20, exclude=[5,10,15])
# 4

frequencies on 100k runs: