I’m trying to pass a user defined function pct
to Pandas agg
method, and it works if I only pass that function but it doesn’t when I use the dictionary format for defining the functions. Does anyone know why?
import pandas as pd df = pd.DataFrame([[1, 2, 3], [4, 5, 6], [7, 8, 9]], columns=['A', 'B', 'C']) pct = lambda x: len(x)/len(df) df.groupby('A').agg(pct)
returns as expected
B C A 1 0.333333 0.333333 4 0.333333 0.333333 7 0.333333 0.333333
But
aggs = {'B':['pct']} df.groupby('A').agg(aggs)
returns the following error:
AttributeError: 'SeriesGroupBy' object has no attribute 'pct'
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Answer
There is string 'pct'
, need variable pct
– lambda function by removing ''
:
aggs = {'B':pct} print(df.groupby('A').agg(aggs)) B A 1 0.333333 4 0.333333 7 0.333333