Python - pandas export to csv or dat file removing None or numpy.nan

Question

When exporting a dataframe df to a dat file, how to remove the None or numpy.nan in the file? I just need an empty value.

df.to_csv('test.dat')

I have tried:

df = df.fillna('')

or

df = df.replace(numpy.nan, '') and df = df.replace(None, '')

But I still see 'None' or 'nan' in the csv or dat file.

Answer 1

Use the parameter

na_rep : string, default ” Missing data representation"

and set this to ""

which you can read here:

pandas.DataFrame.to_csv

This is the code:

file=pd.DataFrame({"one":[1,2,None,3,4],"two":[5,6,7,np.nan,8]})

file.to_csv("xxxxxxx",na_rep="")

Will lead to:

Answer 2

I found a solution to my own question:

df = df.replace('None','')
df = df.replace('nan','')

It is clear that somehow pandas treat None and numpy.nan as string value here. Not sure why but this solution works.