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, I'd say it's a bug. summary.lm handles this situation fine, but
summary.mlm does not.
I'll take a look...
Duncan Murdoch
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