Another way is with ifelse:
z<-data.frame(x,y)
z$y2 <- ifelse(z$x==5,z$y-1,z$y)
HTH,
Ivan
Le 2/22/2011 18:27, Erik Iverson a écrit :
Is this what you mean?
z[which(z[,"x"] == 5) - 1, "y"]
?which is probably what you're looking for...
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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