try this:
x <- 1:10
y <- 11:20
z <- cbind(x, y)
ind <- x == 5
z[ind, "y"] <- z[ind, "y"] - 1
z
I hope it helps.
Best,
Dimitris
On 2/22/2011 6:18 PM, Hongwei Dong wrote:
Hi, R users,
I'm wondering if I can identify an element in a column by an element in
another column. For example:
x<-1:10
y<-11:20
z<-cbind(x,y)
z
x y
[1,] 1 11
[2,] 2 12
[3,] 3 13
[4,] 4 14
[5,] 5 15
[6,] 6 16
[7,] 7 17
[8,] 8 18
[9,] 9 19
[10,] 10 20
What I want to do is: when x=5, y=y-1
Anyone can tell me how to do this? Thanks.
Gary
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--
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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and provide commented, minimal, self-contained, reproducible code.
