[R] Data manipulation question

[cruz]

On Thu, Nov 6, 2008 at 4:23 PM, Peter Jepsen <PJ at dce.au.dk> wrote:
>
> Here is an example:
>
> id <- c(rep("a",4),rep("b",2), rep("c",5), rep("d",1))
> start <- c(c(0,6,17,20),c(0,1),c(0,5,10,11,50),c(0))
> stop <- c(c(6,12,20,30),c(1,10),c(3,10,11,30,55),c(6))
> data <- as.data.frame(cbind(id,start,stop))
> data
> #    id start stop
> # 1   a     0    6
> # 2   a     6   12
> # 3   a    17   20
> # 4   a    20   30
> # 5   b     0    1
> # 6   b     1   10
> # 7   c     0    3
> # 8   c     5   10
> # 9   c    10   11
> # 10  c    11   30
> # 11  c    50   55
> # 12  d     0    6
>
> So, what I want to end up with is this:
>
> id start stop
> a  0     12   # This patient was transferred at time 6 and discharged at
> time 12. The admission starting at time 17 is therefore irrelevant.
> b  0     10
> c  0     3
> d  0     6
>

Try this:

result <- list()
num <- length(levels(factor(data$id)))
length(result) <- 3*num
dim(result) <- c(3,num)
result <- data[data$start == 0,]
Y <- as.integer(row.names(result))

for (i in 1:num) {
  if (Y[i] == dim(data)[1]) (result[i,3] <- data[dim(data)[1],3])
  else (result[i,3] <- data[Y[i]+1,3])
}
result


Sorry it is ugly cuz i am new too but hopefully it gives you some ideas.