[R] Taking the sum of only some columns of a data frame

[William Michels]

I'm sure there are more efficient ways, but this works:

> test1 <- matrix(runif(50), nrow=10, ncol=5)
> ## test1 <- as.data.frame(test1)
> test1 <- rbind(test1, NA)
> test1[11, c(1,3)] <- colSums(test1[1:10,c(1,3)])
> test1


HTH,

Bill.

William Michels, Ph.D.



On Fri, Mar 31, 2017 at 9:20 AM, Bruce Ratner PhD <br at dmstat1.com> wrote:
>
> Hi R'ers:
> Given a data.frame of five columns and ten rows.
> I would like to take the sum of, say, the first and third columns only.
> For the remaining columns, I do not want any calculations, thus rending their "values" on the "total" row blank. The sum/total row is to be combined to the original data.frame, yielding a data.frame with five columns and eleven rows.
>
> Thanks, in advance.
> Bruce
>
>
> ______________
> Bruce Ratner PhD
> The Significant Statistician™
>
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