[R] Sequence for repeated numbers

[Phil Spector]

Luana -
    It's probably not the most efficient way, but here's
a solution that's not dependent on the grades being sorted:

> grade <- c(4,4,4,5,5,7,7,7,7,8,8,8,9,9,9,9,9,10,10,10)
> unlist(sapply(rle(grade)$lengths,function(x)seq(1,x)))
  [1] 1 2 3 1 2 1 2 3 4 1 2 3 1 2 3 4 5 1 2 3

 					- Phil Spector
 					 Statistical Computing Facility
 					 Department of Statistics
 					 UC Berkeley
 					 spector at stat.berkeley.edu




On Wed, 1 Dec 2010, 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
>
> 	[[alternative HTML version deleted]]
>
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