limit a user to only input values if it's in a previously given list

user_13889152 0
Viewed 91

i'm trying to make the user only pick values from a list and if he picks other values outside the list I want the code to ask again for the correct value

my attempt :

accepted_values = [0, 1, 2, 3, 4]
while True:
            
    print('Enter two numbers from the list :', accepted_values)
    first_num = input("Enter first_num: ")
    second_num = input("Enter second_num: ")
    userinput = []
    userinput.append(int(first_num))
    userinput.append(int(second_num))
    if userinput not in accepted_values:
        print('please enter numbers from this range:', accepted_values)
        continue
    else:
        break

but it results in a loop of it asking me to enter the correct values even if I enter a correct number

if-statement while-loop python loops
5 Answers

You're trying to check if [1, 2] is in accepted_values list. The integers 1 and 2 are SEPERATLY but the literal list [1, 2] isn't. Below is a way around it:

accepted_values = [0, 1, 2, 3, 4]
    while True:
        print('Enter two numbers from the list :', accepted_values)
        first_num = input("Enter first_num: ")
        second_num = input("Enter second_num: ")
        userinput = []
        userinput.append(int(first_num))
        userinput.append(int(second_num))

        # Using "any"
        if any(num not in accepted_values for num in userinput):

            print('please enter numbers from this range:', accepted_values)
            continue
        else:
            break

Using the any statement, you can sort of iterate through the user input while checking if its in accepted values.

user_135286360

You are checking if the entire list userinput is an element of accepted_values. So that means it checks whether [input1, input2] is in [0, 1, 2, 3, 4] instead of asking whether input1 and input2 are in [0, 1, 2, 3, 4]. The simplest way to correct it is to change if userinput not in accepted_values: to if userinput[0] not in accepted_values or userinput[1] not in accepted_values:.

user_100444110

I see perfect usecase for python sets here. Something like this will fit your needs perfectly:

>>> accepted_values = [1,2,3,4]
>>> user_input = [1,4]
>>> set(user_input) <= set(accepted_values )
True
>>>
user_73798590

Your condition checking is wrong. Here is a solution to check by using set:

if not (set(userinput).issubset(set(accepted_values))):

If the above condition is True, means userinput is not a subset of accepted_values.

user_131183270

just move your append method to the else statement:

accepted_values = [0, 1, 2, 3, 4]
while True:
    
    print('Enter two numbers from the list :', accepted_values)
    first_num = input("Enter first_num: ")
    second_num = input("Enter second_num: ")
    
    if first_num not in accepted_values or second_num not in accepted_values:
        print('please enter numbers from this range:', accepted_values)
        continue
    else:
        userinput = []
        userinput.append(int(first_num))
        userinput.append(int(second_num))
        break
user_147170070
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