[SciPy-User] Sum duplicate dates in a series

[josef.pktd at gmail.com]

On Fri, Jan 29, 2010 at 2:13 PM, Pierre GM <pgmdevlist at gmail.com> wrote:
> On Jan 29, 2010, at 2:00 PM, John Hunter wrote:
>> On Fri, Jan 29, 2010 at 12:42 PM, Pierre GM <pgmdevlist at gmail.com> wrote:
>>> On Jan 29, 2010, at 1:16 PM, Robert Ferrell wrote:
>>>> How can I sum data for duplicate dates in a time series?  I can do it
>>>> with a loop, but I wonder if there is some tricky magic I might use.
>>
>> If you can put your data in a record array, you can use
>> matplotlib.mlab.rec_groupby
>>
>> http://matplotlib.sourceforge.net/api/mlab_api.html#matplotlib.mlab.rec_groupby
>>
>> http://matplotlib.sourceforge.net/examples/misc/rec_groupby_demo.html
>
> John,
> Could you have a look into numpy.lib.recfunctions ? That's an attempt to homogenize what you did for matplotlib, and it'd be great if you could help.
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I just wanted to show that there will be some advantages when it is
possible to easily move between packages

>>> import scikits.timeseries as ts
>>> import la
>>> s = ts.time_series([1,2,3,4,5],dates=ts.date_array(["2001-01","2001-01","2001-02","2001-03","2001-03"],freq="M"))
>>> dta = la.larry(s.data, label=[range(len(s.data))])
>>> dat = la.larry(s.dates.tolist(), label=[range(len(s.data))])
>>> s2 = ts.time_series(dta.group_mean(dat).x,dates=ts.date_array(dat.x,freq="M"))
>>> s
timeseries([1 2 3 4 5],
   dates = [Jan-2001 Jan-2001 Feb-2001 Mar-2001 Mar-2001],
   freq  = M)

>>> s2
timeseries([ 1.5  1.5  3.   4.5  4.5],
   dates = [Jan-2001 Jan-2001 Feb-2001 Mar-2001 Mar-2001],
   freq  = M)

>>> s2u = ts.remove_duplicated_dates(s2)
>>> s2u
timeseries([ 1.5  3.   4.5],
   dates = [Jan-2001 ... Mar-2001],
   freq  = M)

>>> s2u.dates
DateArray([Jan-2001, Feb-2001, Mar-2001],
          freq='M')

It's not so easy yet. But it would be nice if we can use timeseries,
pandas and la for different things depending on the more convenient
representation.

Josef