create a matrix and then use apply:

> g <- 1:5;
>
>  from <- 1:3;
>  to <- 3:5;
>
> index <- cbind(from,to)
> apply(index, 1, function(x) sum(g[x[1]:x[2]]))
[1]  6  9 12
>



On 3/27/06, Fred J. <phddas@yahoo.com> wrote:
>
> Dear R users
>
> I am trying to sum selective elements of a vector but my solution
> is not cutting it.
>
> Example:
> > g <- 1:5;
>
> > from <- 1:3;
> > to <- 3:5;
> from to
> 1       3
> 2       4
> 3       5
>
> so I expect 3 sums from g
> 1+2+3  that is 1 to 3 of g
> 2+3+4  that is 2 to 4 of g
> 3+4+5  that is 3 to 5 of g
>
> my solution will not work.
> sum.em <- function(g, c1, c2) sum(g[c1:c2])
> apply(g, 1, sum.em, ...) I don't think so because apply is not
> aware of the from and to. and if I f <- list(g, from, to) that will not
> fit with the second arg of apply.
>
> thank you
>
>
> ---------------------------------
>
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>
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--
Jim Holtman
Cincinnati, OH
+1 513 646 9390 (Cell)
+1 513 247 0281 (Home)

What the problem you are trying to solve?

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