Hi Luana,

Try this:

ID <- 1:20
grade <- c(4, 4, 4, 5, 5, 7, 7, 7, 7, 8, 8, 8, 9, 9, 9, 9, 9, 10, 10, 10)
d <- data.frame(ID, grade)
d$Sequence <- do.call(c, sapply(rle(grade)$lengths, seq))
d

HTH,
Jorge


On Wed, Dec 1, 2010 at 11:08 AM, Luana Marotta <> wrote:

> Hello fellows,
>
> I would like to create a sequence for repeated numbers in a dataset. For
> example:
>
> ID <- c(1:20)
> grade <- c(4,4,4,5,5,7,7,7,7,8,8,8,9,9,9,9,9,10,10,10)
>
> Data:
>
> ID  Grade
> 1   4
> 2   4
> 3   4
> 4   5
> 5   5
> 6   7
> 7   7
> 8   7
> 9   7
> (...)
>
> I would like to create a variable "sequence":
>
> Data:
> ID Grade    Sequence:
> 1   4          1
> 2   4          2
> 3   4          3
> 4   5          1
> 5   5          2
> 6   7          1
> 7   7          2
> 8   7          3
> 9   7          4
>
> Any help is very much appreciate!
>
> Thank you,
>
> Luana Marotta
>
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>
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