[R] identify an element in a column

[Erik Iverson]

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
> 
> 	[[alternative HTML version deleted]]
> 
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