How To Do A Groupby On An Empty Set Of Columns In Pandas?
I am hitting on a corner case in pandas. I am trying to use the agg fn but without doing a groupby. Say I want an aggregation on the entire dataframe, i.e. from pandas import * DF
Solution 1:
It's not so great either, but for this case, if you pass a function returning True at least it wouldn't require changing df
:
>>>from pandas import *>>>df = DataFrame( np.random.randn(5,3), index = list( "ABCDE"), columns = list("abc") )>>>df.groupby(lambda x: True).agg({'a' : np.sum, 'b' : np.mean } )
a b
True 1.836649 -0.692655
>>>>>>df['total'] = 'total'>>>df.groupby(['total']).agg({'a' : np.sum, 'b' : np.mean } )
a b
total
total 1.836649 -0.692655
You could use various builtins instead of lambda x: True
but they're less explicit and only work accidentally.
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