Python Global Variable Problem

[LtStaffel]

Hello,

 

I don't see what I did wrong with my code here, though obviously, I did.

If someone could point out where I went wrong, I'd appreciate it.

 

tempList = []
def average(listTemps):
    return float(sum(listTemps)) / max(len(listTemps), 1)
iterator = 0
def end():
    global iterator
    if tempList[iterator] < average(tempList):
        print str(tempList[iterator]) + " is less than the average."
        iterator += 1
        end()
    elif tempList[iterator] > average(tempList):
        print str(tempList[iterator]) + " is more than the average."
        iterator += 1
        end()
    else:
        print str(tempList[iterator]) + " is equal to the average."
        iterator += 1
        end()
counter = 1
def askMain():
    global counter
    temp = input("Please enter a temperature, " + str(counter) + " of 7: ")
    tempList.append(temp)
    if counter <= 7:
        askMain()
        global counter
        counter += 1
    else:
        end()
askMain()

 

Thanks in advance

-LtStaffel

[Mr_KoKa]

You see, you never add 1 to counter, because first what you do you run another askMain function, so you never reach that line where counter is increased, also you don't need that second global counter thing. That for counter, you will probably encounter more errors after you fix this one.

[fizzlesticks]

1 hour ago, LtStaffel said:

If someone could point out where I went wrong, I'd appreciate it.

1. You're using Python 2. Unless you have a really good reason, don't do that.

2. Don't use global variables if at all possible.

3. Your use of recursion is weird and unnecessary.

 

Here's your code rewritten in Python 3.6

Spoiler

#! /usr/bin/env python3.6


def main():
    temps = [float(input(f'Please enter a temperature, {i} of 7: ')) for i in range(8)]
    average = sum(temps) / len(temps)

    for t in temps:
        if t < average:
            print(f'{t} is less than the average.')
        elif t > average:
            print(f'{t} is more than the average.')
        else:
            print(f'{t} is equal to the average.')

if __name__ == '__main__':
    main()

 

 

[LtStaffel]

7 minutes ago, fizzlesticks said:

1. You're using Python 2. Unless you have a really good reason, don't do that.

2. Don't use global variables if at all possible.

3. Your use of recursion is weird and unnecessary.

 

Here's your code rewritten in Python 3.6

  Hide contents

#! /usr/bin/env python3.6


def main():
    temps = [float(input(f'Please enter a temperature, {i} of 7: ')) for i in range(8)]
    average = sum(temps) / len(temps)

    for t in temps:
        if t < average:
            print(f'{t} is less than the average.')
        elif t > average:
            print(f'{t} is more than the average.')
        else:
            print(f'{t} is equal to the average.')

if __name__ == '__main__':
    main()

 

 

I appreciate the re-write of my script, but using recursion over loops was part of the challenge in making this program.

What should I use instead to make this work?

I can use 3.

[LtStaffel]

1 hour ago, Mr_KoKa said:

You see, you never add 1 to counter, because first what you do you run another askMain function, so you never reach that line where counter is increased, also you don't need that second global counter thing. That for counter, you will probably encounter more errors after you fix this one.

I thought making the variable global would fix that.

[fizzlesticks]

19 minutes ago, LtStaffel said:

using recursion over loops was part of the challenge in making this program.

Unfortunately I don't know how to help you there, recursion just doesn't make sense for this problem.

 

19 minutes ago, LtStaffel said:

I thought making the variable global would fix that.

The problem is that you're recursing before you increment the counter. So in every recursive call you'll have a value of 0 for counter, your if statement returns true, then you make another recursive call and eventually reach Python's very small recursive call limit. 

Moving the increment up before the recursive call will give counter the value 0 then 1 then 2 etc as expected.

[LtStaffel]

7 hours ago, Erik Sieghart said:

I'm guessing it was homework. There's no application for recursion outside of academia

Actually I'm learning Haskell and thought I could pull off this program in Python without loops after seeing how recursion worked in Haskell.

 

I am trying to learn new ways of going about things, even if recursion doesn't make sense in this particular case or most cases, I figure knowing how to do the same thing in more than one way can't hurt

[LtStaffel]

2 hours ago, Erik Sieghart said:

Recursion is something to know so that you know not to.

Not in a functional programming language unfortunately

[Mira Yurizaki]

11 hours ago, Erik Sieghart said:

I'm guessing it was homework. There's no application for recursion outside of academia

Recursion works really well when you need to traverse a tree or some other similar data structure.

 

Many would say if you use a "goto" statement in your code, you should have an anvil dropped on your head. Well, they can go ahead and mail one to Linus Torvalds, because there's at least one "goto" statement in the Linux kernel code.

[straight_stewie]

def main():
    temps = [float(input(f'Please enter a temperature, {i} of 7: ')) for i in range(8)]
    average = sum(temps) / len(temps)

    for t in temps:
        if t < average:
            print(f'{t} is less than the average.')
        elif t > average:
            print(f'{t} is more than the average.')
        else:
            print(f'{t} is equal to the average.')

if __name__ == '__main__':
    main()

HEY!! An F-String. That's the first code example I've seen of one outside of PEP-498. I guess I should upgrade to 3.6, but my classes won't accept it.