Hi, There,

 

I would like to subtotal the number in a specified column for all rows
having the same data for specified columns. The following is the simple
example:

 

 

> x=matrix(c(1,2,2,0.3,2,2,2,0.5,1,2,1,0.2),3,4,byrow=T)

> rownames(x)=c("R1","R2","R3")

> colnames(x)=c("C1","C2","C3","F")

> x

   C1 C2 C3   F

R1  1  2  2 0.3

R2  2  2  2 0.5

R3  1  2  1 0.2

 

I would like to get the subtotal in column "F" based on same row data in
column "C1" and "C2". The result should be like

 

C1 C2 SumF

1    2    0.5          # This is 0.3 + 0.2 from R1 and R3

2    2    0.5

 

Is there a simple way to do this? Any help will be greatly appreciated.

 

Qiaoping Yuan

 


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