保存数据框列并更新

Question

I am trying to save a pandas dataframe column instance. but the instance disappears once I make an update in that column, I can't get access to the old instance anymore.

C= DF.loc[:,'10']
print(C)
DF.loc[:,'10'] = None
print(C)

In the first print I get the last instance of DF.loc[:,'10'] , in the second one I get a None column. How should I do to save the old instance to use it later? Does python make an update on variables of the dataframe even when I already saved it? Thanks for helping.

Answer 1

In python, setting a variable actually sets a reference to the variable. Variable names in python are references to the original.

The following code should make a copy of C and store in D

C= DF.loc[:,'10']
print(C)
D= DF.loc[:,'10'].copy()

DF.loc[:,'10'] = None
print(C)