'NaTType' object has no attribute 'days'

I have a column in my dataset which represents a date in ms and sometimes its values is nan (actually my columns is of type str and sometimes its valus is 'nan'). I want to compute the epoch in days of this column. The problem is that when doing the difference of two dates:

(pd.to_datetime('now') - pd.to_datetime(np.nan)).days

if one is nan it is converted to NaT and the difference is of type NaTType which hasn't the attribute days.

In my case I would like to have nan as a result.

Other approach I have tried: np.datetime64 cannot be used, since it cannot take as argument nan. My data cannot be converted to int since int doesn't have nan.


It will just work even if you filter first:

In [201]:
df = pd.DataFrame({'date':[dt.datetime.now(), pd.NaT, dt.datetime(2015,1,1)]})

0 2015-08-28 12:12:12.851729
1                        NaT
2 2015-01-01 00:00:00.000000

In [203]:
df.loc[df['date'].notnull(), 'days'] = (pd.to_datetime('now') - df['date']).dt.days

                        date  days
0 2015-08-28 12:12:12.851729    -1
1                        NaT   NaN
2 2015-01-01 00:00:00.000000   239