Groupby aggregate based on multiple condition pandas - pandas

Question

I have a data frame as shown below
Sector Plot Year Amount Month
SE1 1 2017 10 Sep
SE1 1 2018 10 Oct
SE1 1 2019 10 Jun
SE1 1 2020 90 Feb
SE1 2 2018 50 Jan
SE1 2 2017 100 May
SE1 2 2018 30 Oct
SE2 2 2018 50 Mar
SE2 2 2019 100 Jan
From the above I would like to prepare below data frame
Sector Plot Number_of_Times Mean_Amount Recent_Amount Recent_year Recent_Month
SE1 1 4 30 50 2020 Feb
SE1 2 3 60 30 2018 Oct
SE2 2 2 75 100 2019 Jan

Answer 1

So if all rows are sorted in input data use GroupBy.agg with named aggregations:
df1 = (df.groupby(['Sector','Plot']).agg(Number_of_Times=('Year','size'),
Mean_Amount=('Amount','mean'),
Recent_Amount=('Amount','last'),
Recent_year=('Year','last'),
Recent_Month=('Month','last')).reset_index())
print (df1)
Sector Plot Number_of_Times Mean_Amount Recent_Amount Recent_year \
0 SE1 1 4 30 90 2020
1 SE1 2 3 60 30 2018
2 SE2 2 2 75 100 2019
Recent_Month
0 Feb
1 Oct
2 Jan
If necessary sorting convert Month to datetimes, add DataFrame.sort_values, apply solution and last convert months back to strings:
df['Month'] = pd.to_datetime(df['Month'], format='%b')
df1 = (df.sort_values(['Sector','Plot','Year','Month'])
.groupby(['Sector','Plot']).agg(Number_of_Times=('Year','size'),
Mean_Amount=('Amount','mean'),
Recent_Amount=('Amount','last'),
Recent_year=('Year','last'),
Recent_Month=('Month','last')).reset_index())
df1['Recent_Month'] = df1['Recent_Month'].dt.strftime('%b')
print (df1)
Sector Plot Number_of_Times Mean_Amount Recent_Amount Recent_year \
0 SE1 1 4 30 90 2020
1 SE1 2 3 60 30 2018
2 SE2 2 2 75 100 2019
Recent_Month
0 Feb
1 Oct
2 Jan
Another idea, buggy in pandas 0.25.1:
months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
df['Month'] = pd.Categorical(df['Month'] , ordered=True, categories=months)
df1 = (df.sort_values(['Sector','Plot','Year','Month'])
.groupby(['Sector','Plot']).agg(Number_of_Times=('Year','size'),
Mean_Amount=('Amount','mean'),
Recent_Amount=('Amount','last'),
Recent_year=('Year','last'),
Recent_Month=('Month','last')).reset_index())
print (df1)
ValueError: Buffer dtype mismatch, expected 'Python object' but got 'long long'