[R] create a vector looping over a frame
Thomas W Blackwell
tblackw at umich.edu
Sat Jul 19 00:15:17 CEST 2003
On Fri, 18 Jul 2003, Siddique, Amer wrote:
> I have a data.frame
>
> > names(popA)
> [1] "Year" "Series" "Age" "WM" "WF" "HM" "HF" "BM"
> [9] "BF" "IM" "IF" "AM" "AF" "Yr"
>
> how do i loop over a subset of variables in this frame to create a vector of
> length equal to the number of variables in the subset such that the vector's
> ith element is the result of an aggregate fncn applied to the ith variable?
>
> eg,
> sumvar<-c(sum(WM),...,sum(AF))
sumvar <- sapply(popA[ ,4:13], sum)
You can use any function, even a user-written one, in place of sum().
When you see the help for sapply(), remember that a data.frame is
also a list ("inherits" from list).
- tom blackwell - u michigan medical school - ann arbor -
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