CODEWITHSUNDEEP
pythonpandaspandas-groupby
Talha Anwar
Talha Anwar

Reputation: 2959

Pass an argument to a function in groupby aggregate pandas

I have a dummy data frame as follows

import pandas as pd
df=pd.DataFrame({
    'ID':[1,1,2,2,2,3,4,5,5],
    'workday':[1,2,1,2,3,1,1,1,2]
    })

I have these two aggregate functions

df.groupby('ID').agg(['first','last'])

df.groupby('ID').agg('nth',-2)

I tried lambda x: x.nth(-2) but it says AttributeError: 'Series' object has no attribute 'nth' I want to pass them at once in one groupby aggregate function

Upvotes: 1

Views: 166

Answers (1)

jezrael
jezrael

Reputation: 862691

One idea:

df = df.groupby('ID').agg(['first','last', lambda x: x.iloc[-2] if len(x) > 1 else np.nan])
print (df)
   workday                
     first last <lambda_0>
ID                        
1        1    2        1.0
2        1    3        2.0
3        1    1        NaN
4        1    1        NaN
5        1    2        1.0

Upvotes: 1

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