[Rd] Bug in model.matrix.default (was: [R] predict incosistency ?) (PR#1100)
murdoch@stats.uwo.ca
murdoch@stats.uwo.ca
Tue, 25 Sep 2001 15:52:53 +0200 (MET DST)
On Tue, 25 Sep 2001 12:27:27 GMT, Jorge Luis Ojeda Cabrera
<jojeda@posta.unizar.es> wrote in message
<20010925.12272700@macdesp8.unizar.es>:
>When fitting model 'y~1', the 'lm' response is ok, but it is not possible
>to get predictions using 'predict'. May be this is a bug, at least i
>think it is somehow
>inconsistent.
It still appears in 1.3.1, I think it's a bug. It shows up when you
use the newdata parameter to predict.lm; if you just ask for
predictions without specifying the x value things are fine:
> d _ data.frame(x=runif(5),y=runif(5))
> d1.lm _ lm(y ~ 1, data=d)
>
> # This one is okay:
>
> predict(d1.lm)
1 2 3 4 5
0.486269 0.486269 0.486269 0.486269 0.486269
>
> # This one triggers the bug:
>
> predict(d1.lm,newdata=data.frame(x=0.5))
Error in model.matrix.default(delete.response(tt), newdata, contrasts
= object$contrasts, :
subscript out of bounds
There are 3 lines in model.matrix.default that assume that there is at
least one predictor in the model: they index various things by "-1"
to remove it. I can't follow what's going on there well enough to fix
it.
Duncan Murdoch
Version:
platform = i386-pc-mingw32
arch = x86
os = Win32
system = x86, Win32
status =
major = 1
minor = 3.1
year = 2001
month = 08
day = 31
language = R
Windows 98 4.10 (build 1998)
Search Path:
.GlobalEnv, package:ctest, Autoloads, package:base
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