Instantiate variables to None in Python

Why do these two blocks of code not do the same thing?

category = None
prodid_brand = None
prod_type = None
prod_application = None
prod_handletype = None
prod_series = None

I wanted to “clean up” my code by doing the following, but it does not work the same as the code above.

column_list = [category, prodid_brand, prod_type, prod_application, 
               prod_handletype, prod_series]

for col in column_list:
    col = None

Also is there a “cleaner” way to instantiate all the variables than the top block of code.

Answer

The other answers are great ways to more cleanly/efficiently set all the variables to None.

However, to answer this question:

Why do these two blocks of code not do the same thing?

The reason is, with your first line

column_list = [category, prodid_brand, prod_type, prod_application, 
               prod_handletype, prod_series]

you’re actually setting the variable at each index in the list equal to each of those variables. So, column_list[0] = category, column_list[1] = prodid_brand, etc.

Then with the next lines

for col in column_list:
    col = None

you just changing the variable at each of those list indexes, and setting them to None (equivalent to column_list[0] = None).

Hence why none of your initial variables (category, prodid_brand, etc) are getting set, and you’re ending up with a list of six None values instead.