pandas: where is the documentation for TimeGrouper?

Question

I use Pandas a lot and its great. I use TimeGrouper as well, and its great. I actually dont know where is the documentation about TimeGrouper. Is there any?

Thanks!

Answer 1

pd.TimeGrouper() was formally deprecated in pandas v0.21.0 in favor of pd.Grouper().

The best use of pd.Grouper() is within groupby() when you're also grouping on non-datetime-columns. If you just need to group on a frequency, use resample().

For example, say you have:

>>> import pandas as pd >>> import numpy as np >>> np.random.seed(444)  >>> df = pd.DataFrame({'a': np.random.choice(['x', 'y'], size=50),                        'b': np.random.rand(50)},                       index=pd.date_range('2010', periods=50)) >>> df.head()             a         b 2010-01-01  y  0.959568 2010-01-02  x  0.784837 2010-01-03  y  0.745148 2010-01-04  x  0.965686 2010-01-05  y  0.654552 

You could do:

>>> # `a` is dropped because it is non-numeric >>> df.groupby(pd.Grouper(freq='M')).sum()                   b 2010-01-31  18.5123 2010-02-28   7.7670 

But the above is a little unnecessary because you're only grouping on the index. Instead you could do:

>>> df.resample('M').sum()                     b 2010-01-31  16.168086 2010-02-28   9.433712 

to produce the same result.

Conversely, here's a case where Grouper() would be useful:

>>> df.groupby([pd.Grouper(freq='M'), 'a']).sum()                    b            a         2010-01-31 x  8.9452            y  9.5671 2010-02-28 x  4.2522            y  3.5148 

For some more detail, take a look at Chapter 7 of Ted Petrou's Pandas Cookbook.

Answer 2

pandas.TimeGrouper() was deprecated in favour of pandas.Grouper() in pandas v0.21.

Use pandas.Grouper() instead.