All days instead of business days?
Hi, 

I am very new to github and miss a discussion board for pandas. Not sure if issues is the right place for my question, so feel free to delete it, but please point to the right place for questions.

The question: I need to aggregate hourly time series to the daily scale, that would include all days, 7 per week. Currently i find only bday class in datetools:

<pre>
daily_ts = ts.groupby(lambda x: datetools.bday(x)).aggregate(np.nansum)
</pre>


But bday will skip weekends. datetools.day seem to return timeseries with the same time resolution. 
How to include weekend days?

Many thanks for developing pandas, it's truly nice, and really fast, even when working with large datasets!
