Dear Steve,
Using Jim Holtman's x data, you can also try the following for columns 3 and
4:
a <- with(x, apply(x[,3:4], 2, tapply, site,function(x) cumsum(x)))
x[,c('cvar1','cvar2')] <- do.call(cbind,lapply(a, function(x) do.call(c,x)))
x
HTH,
Jorge
On Wed, Jun 17, 2009 at 11:48 AM, SEUNG CHEON HONG <[email protected]>wrote:
> Dear R-Help List,
>
> I have a question about data manipulation. I tried to make code myself but
> too much for me. I would greatly appreciate your help.
>
> I have data set consisting of site (from 1 to N1) and distance and there
> are several variables (1 to N2) collected from each sampling site. I am
> interested in looking at cumulative sums of each variable based on site and
> distance like below.
>
> Can anyone help create function to do the task? The cumulative sum outputs
> may not be necessarily combined with original data. It will be better to
> have only cumulative sum outputs and indicator variables of interest.
>
> site distance var1
var(n2) cu.sum.v1
> cu.sum.v(n2)
> 1 10 1 0 1 0
> 1 20 0 1 1 1
> 1 30 1 2 2 3
> 1 40 3 3 5 6
> 1 50 1 4 6 10
> 2 10 1 1 1 1
> 2 20 2 1 3 2
> 2 30 4 1 7 3
> 2 40 0 1 7 4
> 2 50 1 1 8 5
> ,,, ,,, ,,, ,,, ,,,
> n1 10 1 1 1 1
> n1 20 1 0 2 1
> n1 30 1 1 3 2
> n1 40 1 0 4 2
> n1 50 1 1 5 3
>
>
> Thank you very much for reading and time!!!
>
> Steve Hong
>
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