[R] Create a new var reflecting the order of subjects in existing var

[Gabor Grothendieck]

Assuming the ID's are contiguous, as in your example:

   transform(dat, IDorder = seq(ID) - match(ID, ID) + 1)


On 4/1/07, Nguyen Dinh Nguyen <n.nguyen at garvan.org.au> wrote:
> Dear R helpers
> I have a data set sth like this:
> set.seed(123);dat <- data.frame(ID= c(rep(1,2),rep(2,3), rep(3,3), rep(4,4),
> rep(5,5)),
>                  var1 =rnorm(17, 35,2),
>                  var2=runif(17,0,1))
> dat
>   ID     var1       var2
> 1   1 33.87905 0.02461368
> 2   1 34.53965 0.47779597
> 3   2 38.11742 0.75845954
> 4   2 35.14102 0.21640794
> 5   2 35.25858 0.31818101
> 6   3 38.43013 0.23162579
> 7   3 35.92183 0.14280002
> 8   3 32.46988 0.41454634
> 9   4 33.62629 0.41372433
> 10  4 34.10868 0.36884545
> 11  4 37.44816 0.15244475
> 12  4 35.71963 0.13880606
> 13  5 35.80154 0.23303410
> 14  5 35.22137 0.46596245
> 15  5 33.88832 0.26597264
> 16  5 38.57383 0.85782772
> 17  5 35.99570 0.04583117
> I would like to create a new var in dat which reflects the order of each
> subject (ID), like this
>   ID     var1       var2        IDorder
> 1   1 33.87905 0.02461368       1
> 2   1 34.53965 0.47779597       2
> 3   2 38.11742 0.75845954       1
> 4   2 35.14102 0.21640794       2
> 5   2 35.25858 0.31818101       3
> 6   3 38.43013 0.23162579       1
> 7   3 35.92183 0.14280002       2
> 8   3 32.46988 0.41454634       3
> 9   4 33.62629 0.41372433       1
> 10  4 34.10868 0.36884545       2
> 11  4 37.44816 0.15244475       3
> 12  4 35.71963 0.13880606       4
> 13  5 35.80154 0.23303410       1
> 14  5 35.22137 0.46596245       2
> 15  5 33.88832 0.26597264       3
> 16  5 38.57383 0.85782772       4
> 17  5 35.99570 0.04583117       5
>
> Thank you very much for your help
> Regards
> Nguyen
>
>
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