Datetime objects with pandas mean function

Question

I am new to programming so I apologize in advance if this question does not make any sens. I noticed that when I try to calculate the mean value of a pandas data frame with

Answer 1

To simplify Alex's answer (I would have added this as a comment but I don't have sufficient reputation):

import datetime
import pandas as pd

d={'one': pd.Series([1, 2, 3], index=['a', 'b', 'c']), 
   'two': pd.Series([datetime.datetime(2014, 7, 9), 
           datetime.datetime(2014, 7, 10), 
           datetime.datetime(2014, 7, 11) ], 
           index=['a', 'b', 'c'])}
df = pd.DataFrame(d)

Which looks like:

   one   two
a   1   2014-07-09
b   2   2014-07-10
c   3   2014-07-11

Then calculate the mean of column "two" by:

(df.two - df.two.min()).mean() + df.two.min()

So, subtract the min of the timeseries, calculate the mean (or median) of the resulting timedeltas, and add back the min.