try this:
x <- factor(c('a','a','a','a','a','b','b','b','c','d','d','d'))
y <- c(1,3,6,8,8,3,4,7,5,6,7,10)
X <- data.frame(x, y)
cbind(X, z = ave(X$y, X$x,
FUN = function (x) match(x, unique(x)) - 1))
I hope it helps.
Best,
Dimitris
On 2/17/2011 11:15 AM, mathijsdevaan wrote:
Here is a method that works despite generating a warning:
cbind(X, z = ave(X$y, X$x, FUN = seq) - 1)
David Winsemius, MD
West Hartford, CT
I was happy a bit too early. There's still an error:
x<-as.factor(c('a','a','a','a','a','b','b','b','c','d','d','d'))
y<-c(1,3,6,8,8,3,4,7,5,6,7,10)
X<-data.frame(x,y)
X
x y
1 a 1
2 a 3
3 a 6
4 a 8
5 a 8
6 b 3
7 b 4
8 b 7
9 c 5
10 d 6
11 d 7
12 d 10
cbind(X, z = ave(X$y, X$x, FUN = seq) - 1)
x y z
1 a 1 0
2 a 3 1
3 a 6 2
4 a 8 3
5 a 8 4
6 b 3 0
7 b 4 1
8 b 7 2
9 c 5 0
10 d 6 0
11 d 7 1
12 d 10 2
Using this function provides a value of 4 in row 5, column c, while it
should be 3. Is there another way I can solve my problem? Thanks!
M
--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
Web: http://www.erasmusmc.nl/biostatistiek/
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