Dear Krishna,
Here is one way. It is not very elegant, but seems to work:

# x is the vector you want to change
foo <- function(x){
   R1 <- rle(!is.na(x))
   R2 <- rle(is.na(x))
   len <- R1$lengths[!R2$values]
   x[!is.na(x)] <- rep(1:length(len), len)
   x
  }

# Example
x <- c(10, 8, 1, 3, 0, 8, NA, NA, NA, NA, 2, 1, 6, NA, NA, NA, 0, 5, 1, 9)
foo(x)
# [1]  1  1  1  1  1  1 NA NA NA NA  2  2  2 NA NA NA  3  3  3  3

HTH,

Jorge


On Tue, Jul 7, 2009 at 5:08 PM, Krishna Tateneni <tateneni@gmail.com> wrote:

> Greetings, I have a vector of the form:
> [10,8,1,3,0,8,NA,NA,NA,NA,2,1,6,NA,NA,NA,0,5,1,9...]  That is, a
> combination
> of sequences of non-missing values and missing values, with each sequence
> possibly of a different length.
>
> I'd like to create another vector which will help me pick out the sequences
> of non-missing values.  For the example above, this would be:
> [1,1,1,1,1,1,NA,NA,NA,NA,2,2,2,NA,NA,NA,3,3,3,3...].  The goal ultimately
> is
> to calculate means separately for each sequence.
>
> Your help is appreciated.  If I'm making this more complicated than
> necessary, I'd appreciate knowing that as well!
>
> Many thanks.
>
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>
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