python : Collatz Sequence

Question

I am a beginner in python. I found this problem in the book Automate the Boring Stuff with Python. How can I improve this program using latest version of python.

def generateCollatzSequence(number):
    print(str(number) + " ")

    while number != 1:
        if number % 2 == 0:
            number = number / 2
            print(str(number) + " ")

        elif number % 2 == 1:
            number = (3 * number) + 1
            print(str(number) + " ")

#print("Enter number: ")
inputNumber = int(input("Enter number: "))
generateCollatzSequence(inputNumber)

Answer 1

• Your function is called generate but it doesn't return anything. Instead display would be a better name.
• It would be better if you had two functions one to generate the values, one to display them.
• Function names should be lower_snake_case to be idiomatic.
• + " " is not needed, as print makes the value go to the next line anyway.
• str(number) also isn't needed as print will do this automatically for you.

Thanks @Toby Speight:

• You can move the print to be after both the if and the else.

def generate_collatz_sequence(number):
    output = [number]
    while number != 1:
        if number % 2 == 0:
            number = number / 2
        elif number % 2 == 1:
            number = (3 * number) + 1
        output.append(number)

def display_collatz_sequence(values):
    for number in values:
        print(number)

If you want this to still display values in real time, then you can make generate_collatz_sequence a generator function.

def generate_collatz_sequence(number):
    yield number
    while number != 1:
        if number % 2 == 0:
            number = number / 2
        elif number % 2 == 1:
            number = (3 * number) + 1
        yield number