Sequence for repeated numbers

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

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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Sequence for repeated numbers

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