Create a generic version of convert_to_annual function in scikits.timeseries

[wesm]

The name is a misnomer. It's really a pivot operation

[timmie]

Link to scikits.timeseries meta issue:
https://github.com/wesm/pandas/issues/630

[wesm]

This kind of stuff would be nice to be able to do too: http://stackoverflow.com/questions/10458493/pandas-how-to-plot-yearly-data-on-top-of-each-other

[timmie]

Is it planned to integrate this into 0.8 final?

[changhiskhan]

No, we pushed this off to 0.9.0 for now

[wesm]

@timmie: there is a version of it already in pandas/tseries/util.py, but I need people like you to give me some more guidance on what features of it are actually required (we're talking about a 15 line function here). I suspect that pandas's groupby capability makes convert_to_annual less useful than it was in scikits.timeseries

[timmie]

OK, very nice.
I will give it a try until the end of the week.

Is it also possible to do such operations on dataframes?
Case:
I have a data frame with datetime index with temperature, precipitation and wind speed for 10 years. Now I would like to get the annual average for all 3 parameters at once.

[wesm]

Wouldn't df.resample('A') be what you want?

[wesm]

Or otherwise df.groupby(lambda x: x.year).mean()

[timmie]

Please help, I am getting the following errors:

>>> pivot_annual(ser, freq='A')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/pymodules/python2.7/pandas/tseries/util.py", line 58, in pivot_annual
    raise NotImplementedError(freq)
NotImplementedError: A

>>> pivot_annual(ser)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/pymodules/python2.7/pandas/tseries/util.py", line 58, in pivot_annual
    raise NotImplementedError(freq)
NotImplementedError: None
>>> 

[timmie]

Please addd util to namespace
I had to do

from pandas.tseries.util import pivot_annual

[timmie]

I suspect that

df.groupby(lambda x: x.year).mean()

Does not achieve a equal alignement over years for all parameters as commented in #736 (comment)

[wesm]

Why wouldn't it?