On 26/10/2011 9:48 AM, Helios de Rosario wrote:
When I fit a multivariate linear model, and the formula is defined
outside the call to lm(), the method summary.mlm() fails.
This works well:
> y<- matrix(rnorm(20),nrow=10)
> x<- matrix(rnorm(10))
> mod1<- lm(y~x)
> summary(mod1)
...
But this does not:
> f<- y~x
> mod2<- lm(f)
> summary(mod2)
Error en object$call$formula[[2L]]<- object$terms[[2L]]<-
as.name(ynames[i]) :
objeto de tipo 'symbol' no es subconjunto
I would say that the problem is in the following difference:
> class(mod1$call$formula)
[1] "call"
> class(mod2$call$formula)
[1] "name"
As far as I understand, summary.mlm() creates a list of .lm objects
from the individual columns of the matrices in the .mlm object, and then
it tries to change the second element of object$call$formula, to present
the name of the corresponding column as the response variable. But if
the formula has been defined outside the call to lm(), that element
cannot be modifed that way.
A bug, perhaps?
Yes, it was a bug. A simple workaround is the following:
mod2$call$formula <- formula(mod2)
I'll add that to summary.mlm, but in the meantime, you can just do it
yourself.
Duncan Murdoch
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
