[R] why "object 'x' not found"?
murdoch.duncan at gmail.com
Thu Feb 7 19:30:41 CET 2013
On 07/02/2013 1:20 PM, Winfried Moser wrote:
> Dear Listers,
> I try to change the structure of my data. i have an indicator-matrix and
> want to end up with a factor.
> i have
> v1 v2 v3
> 1 0 0
> 0 1 0
> 0 0 1
> and want
> v1 v2 v3 v4
> 1 0 0 1
> 0 1 0 2
> 0 0 1 3
> amongst other things i tried the following
> d <- data.frame(d1=c(1,0,0), d2=c(0,1,0), d3=c(0,0,1))
> d$nr <- NA
> sapply(1:3, function(x) ifelse(get(paste0("d$d",x))==1,x,d$nr))
> >From R i get the message "Object 'd$d1' not found".
> But why, it's there?
No it's not there. There's a variable called d, but no variable called
d$d1. That's an expression to extract the d1 component from d.
You could parse and eval that expression, but surely it's not the right
way to do this. In your simple example, using d[[x]] would work. In a
more complicated one, you might want something like
components <- names(d)
More information about the R-help