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Dataset.groupby summary methods #122
Description
This may just be a documentation issue but the summary apply and combine methods for the Dataset.GroupBy object seem to be missing.
In [146]:
foo_values = np.random.RandomState(0).rand(3, 4)
times = pd.date_range('2000-01-01', periods=3)
ds = xray.Dataset({'time': ('time', times),
'foo': (['time', 'space'], foo_values)})
ds.groupby('time').mean() #replace time with time.month after #121 is adressed
# ds.groupby('time').apply(np.mean) # also Errors here
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-146-eec1e73cff23> in <module>()
3 ds = xray.Dataset({'time': ('time', times),
4 'foo': (['time', 'space'], foo_values)})
----> 5 ds.groupby('time').mean()
6 ds.groupby('time').apply(np.mean)
AttributeError: 'DatasetGroupBy' object has no attribute 'mean'Adding this functionality, if not already present, seems like a really nice addition to the package.
Activity
shoyer commentedon May 12, 2014
The problem is that it's ambiguous which array you would like to summarize. I suppose we could default to using all noncoordinates? That would be similar to how pandas does its DataFrame.groupby methods.
jhamman commentedon May 12, 2014
Right, although it doesn't have to be ambiguous. Why not just summarize each group along the
group_dim?shoyer commentedon May 12, 2014
We currently don't implement methods like
ds.mean(), which it would make sense to implement before adding the groupby version. But I do think it would be perfectly consistent to say that the mean of a dataset is the dataset given by taking the mean of every variable in the dataset.Implementation of Dataset.groupby summary methods
use `PYPI_USERNAME` GH action secret (pydata#122)