Unbound local error while attempting to reference a list

[molassascookieman]

I have a basic program in which I enter a business' sales, and it can use one of a few functions like finding the top selling store location and similar. Since I am in an intro class, one of these functions is a bubble sort to sort from best selling location to worst selling location, and vice versa.

def sort_hilo():
    n = len(sales)
    e = len(location)
    swapped = True
    while swapped:
        swapped = False
        for i in range(n - 1):
            if sales[i] > sales[i + 1]:
                temp = sales[i]
                sales[i] = sales[i+1]
                sales[i+1] = temp
                swapped = True
                
        for i in range(n - 1):
            if location[i] > location[i + 1]:
                temp = location[i]
                location[i] = location[i+1]
                location[i+1] = temp
                swapped = True
                
        n -= 1
        e-=1
    for i in range(len(sales)):
        location=i+1
        print('Location', location, '$', ('%0.2f'%sales))

both "sales" and "location" in the first few lines are supposed to reference lists that I globally defined in another part of the program.

The problem is, it keeps giving me back the local variable referenced before assignment for the locations list.
"e = len(location)
UnboundLocalError: local variable 'location' referenced before assignment"

But it doesn't give me this error for the sales list! I have no idea how to get it to realize that it is supposed to reference a predefined list instead of a local variable.

[ichabod801]

Global variables cause problems like this. The best way to solve these problems is to use parameters and return values. See the function tutorial on how to do that.

It's only happening for location because you assign to location on line 24, so Python assumes it is meant to be a local variable when it compiles the function.