Pandas Changing the format of NaN values when saving to CSV

Question

I am working with a df and using numpy to transform data - including setting blanks (or \'\') to NaN. But when I write the df to csv - the output contains the string \'nan\' as

Answer 1

User @coldspeed illustrates how to replace nan values with NULL when save pd.DataFrame. In case, for data analysis, one is interested in replacing the "NULL" values in pd.DataFrame with np.NaN values, the following code will do:

import numpy as np, pandas as pd

# replace NULL values with np.nan
colNames = mydf.columns.tolist()
dfVals = mydf.values
matSyb = mydf.isnull().values
dfVals[matSyb] = np.NAN

mydf = pd.DataFrame(dfVals, columns=colNames)    
#np.nansum(mydf.values, axis=0 )
#np.nansum(dfVals, axis=0 )