Python - Random sample from a range whilst avoiding certain values

Question

I have been reading up about the random.sample() function in the random module and have not seen anything that solves my problem.

I know that using random.sample(range(1,100),5) would give me 5 unique samples from the 'population'...

I would like to get a random number in range(0,999) . I could use random.sample(range(0,999),1) but why then am I thinking about using random.sample() ?

I need the random number in that range to not match any number in a separate array (Say, [443,122,738] )

Is there a relatively easy way I could go about doing this?

Also, I am pretty new to python and am definitely a beginner -- If you would like me to update the question with any information I may have missed then I will.

EDIT: Accidentally said random.range() once. Whoops.

Answer 1

One way you can accomplish that is by simply checking the number and then appending it to a list where you can then use the numbers.

import random

non_match = [443, 122, 738]
match = []

while len(match) < 6: # Where 6 can be replaced with how many numbers you want minus 1
    x = random.sample(range(0,999),1)
    if x not in non_match:
        match.append(x)

Answer 2

There are two main ways:

import random

def method1(lower, upper, exclude):
    choices = set(range(lower, upper + 1)) - set(exclude)
    return random.choice(list(choices))

def method2(lower, upper, exclude):
    exclude = set(exclude)
    while True:
        val = random.randint(lower, upper)
        if val not in exclude:
            return val

Example usage:

for method in method1, method2:
    for i in range(10):
        print(method(1, 5, [2, 4]))
    print('----')

Output:

1
1
5
3
1
1
3
5
5
1
----
5
3
5
1
5
3
5
3
1
3
----

The first is better for a smaller range or a larger list exclude (so the choices list won't be too big), the second is better for the opposite (so it doesn't loop too many times looking for an appropriate option).