How to calculate the average of a column using other columns as a reference using excel - r

Question

I have three columns in excel year, month value.
I want to average value considering month and year. In R language this function is done by group_by(). In excel how could this be done?
year month value
2019 1 12
2019 1 34
2019 2 56
2019 2 15
2020 1 16
2020 3 67
2020 4 89
2018 6 123
2018 6 45
2018 7 98
2019 3 53
2019 1 23
2020 1 12
2020 3 1

Answer 1

If one has Office 365 we can use:
=LET(
y,A2:A15,
m,B2:B15,
v,C2:C15,
u,SORT(UNIQUE(CHOOSE({1,2},y,m)),{1,2}),
CHOOSE({1,1,2},u,AVERAGEIFS(v,y,INDEX(u,0,1),m,INDEX(u,0,2))))
Put this in the first cell and it will spill the results.
Once the HSTACK is release we can replace the CHOOSE with it:
=LET(
y,A2:A15,
m,B2:B15,
v,C2:C15,
u,SORT(UNIQUE(HSTACK(y,m)),{1,2}),
HSTACK(u,AVERAGEIFS(v,y,INDEX(u,0,1),m,INDEX(u,0,2))))

Answer 2

Averageifs would do what you want, but you might want to review using the Filter function to duplicate the Group_By() method for other similar procedures. Once grouped, you can sum/average/sort, etc.
Averageifs:
=AVERAGEIFS(C:C,A:A,2018,B:B,6)
Filter:
=filter(C:C,(A:A=2018)*(B:B=6))
=Average(filter(C:C,(A:A=2018)*(B:B=6)))
See this spreadsheet for examples of both. I realize you're using Excel, but these formulas should work on both (though they are not the same)