I'm having trouble with calculating the mean of Timestamps.

I have a few values with Timestamps in my Data Frame, and I want to aggregate the values into a single value with the sum of all values and the weighted mean of the appropriate Timestamps

My input is:

```
         Timestamp        Value
ID      
0   2013-02-03 13:39:00     79
0   2013-02-03 14:03:00     19
1   2013-02-04 11:36:00     2
2   2013-02-04 12:07:00     2
3   2013-02-04 14:04:00     1

```

And I want to aggregate the data using the ID index.

I was able to sum the Values using 

```
manp_func = {'Value':['sum'] }

new_table =table.groupby(level='ID).agg(manp_func)    

```

but, how can I find the weighted mean of the Timestamps related to the values?

Thanks

S.A