Numpy Nan Returning As 'nan'

This is a part of my code: df['ColZ'] = np.where( (df['ColA'] == 'AA') & (df['ColB'] == 'BB'), 'GOOD!', np.where((df['ColA'] == 'BB') &

Solution 1:

Maybe try replace nan to NaN:

df = df.replace('nan', np.nan)