遍历DataFrame并使用null值更新列

Question

I am attempting to loop through a Dataframe and update the column 'GROUP_NAME' with 'REG' where it is null.

for index, row in trax_df.iterrows():
    if row['GROUP_NAME']==None:
        trax_df.loc[index, trax_df['GROUP_NAME']] = 'REG'

I used the above code and it does not give a traceback but it does not update any of the values with 'REG' where 'GROUP_NAME' is Null. What am I missing here?

EDIT:

It has to be a loop to account for future development and eventually I will have to extract the digits out of another column, call it columnB, and concatenate the digits with 'REG'. Therefore, I believe I need the index from the Dataframe to be able to do that.

And there are NaNs in the data.

Answer 1

try this:

trax_df.loc[trax_df.GROUP_NAME.replace('', np.nan).isnull(), 'GROUP_NAME'] = 'REG'

this will include both empty string and NaNs

if you don't have NaNs you can simply do this:

trax_df.loc[trax_df.GROUP_NAME== '', 'GROUP_NAME'] = 'REG'

Answer 2

是None还是空字符串？

trax_df.loc[(trax_df.GROUP_NAME.isnull() | (trax_df.GROUP_NAME = ''), 'GROUP_NAME'] = 'REG'