Python Global Variables - Not Defined?

Question

I\'m running into an issue where a global variable isn\'t \"remembered\" after it\'s modified in 2 different functions. The variable df is supposed to be a data

Answer 1

Yo have to use global df inside the function that needs to modify the global variable. Else (if writing to it) you are creating a local scoped variable of the same name inside the function and your changes wont be reflected to the global one.

p = "bla"

def func():
    print("print from func:", p)      # works, readonly access, prints global one

def func1():
    try: 
        print("print from func:", p)  # error, python does not know you mean the global one
        p = 22                        # because function overrides global with local name   
    except UnboundLocalError as unb:
        print(unb)

def func2():
    global p
    p = "blubb"                       # modifies the global p

print(p)
func()
func1()
print(p)
func2()
print(p)

Output:

bla   # global

print from func: bla    # readonly global

local variable 'p' referenced before assignment  # same named local var confusion

bla    # global
blubb  # changed global