try this:
> x <- as.data.frame(x)
> x
C1 C2 C3 F
R1 1 2 2 0.3
R2 2 2 2 0.5
R3 1 2 1 0.2
> do.call('rbind',by(x, list(x$C1, x$C2), function(z){z$F <- sum(z$F);
z[1,]}))
C1 C2 C3 F
R1 1 2 2 0.5
R2 2 2 2 0.5
>
On 3/23/07, Yuan, Qiaoping (NIH/NIAAA) [E] <[EMAIL PROTECTED]> wrote:
>
> 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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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem you are trying to solve?
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