Global DataFrame not updated python

Question

I have this code:

latitude = pd.DataFrame()
longitude = pd.DataFrame()

datasets = []

datasets.append(latitude)
datasets.append(longitude)

def fun(key, job):
    global latitude
    global longitude

    if(key == 'LAT'):
        latitude = job.copy()
    elif(key == 'LON'):
        longitude = job.copy()

for d in datasets:
    print(d.shape)

Following this: Why does assigning to my global variables not work in Python? I have used the global keyword to ensure that the variables are correctly referenced. However, the values are not updated. Any advice? I have already verified that the if statements are correct as I am able to print something in them.

OUTPUT:

(0, 0)
(0, 0)

Moreover, I am using spyder and I can see that the list contains empty dataframe and also the global variable are empty.

how did you checked that the values are not updated?? and please add output of your values — ddor254
– ddor254, Commented Nov 30, 2017 at 9:00

ddor254 · Accepted Answer · 2017-11-30 09:09:34Z

2

o.k , the problem you have is that you make your program to point to some value in the datasets.append(latitude) and when you change the global latitude latitude = job.copy() , you changing the value of the global variable and not the one in your list datasets.

if you want to see the changed value print out latitude and you will see that the value has changed. or change the value in datasets[0] for latitude value in your loop.

answered Nov 30, 2017 at 9:09

ddor254

1,6381 gold badge14 silver badges28 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Guido Muscioni Over a year ago

This solve the problem, however, should the variable in the list be a reference to the actual global variables? @ddor254

ddor254 Over a year ago

when changing value of the global variable you are changing what it points to. so the reference in the list still points to "old" global variable , but when you assign value to this global variable it now points to other address , which is not updated on the list.

Collectives™ on Stack Overflow

Global DataFrame not updated python

1 Answer 1

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related