[R] problem with predict()

Liaw, Andy andy_liaw at merck.com
Fri Jun 21 19:06:24 CEST 2002


The problem is that xr and xs are both matrices in his example, not vectors.

Andy

> -----Original Message-----
> From: Peter Dalgaard BSA [mailto:p.dalgaard at biostat.ku.dk]
> Sent: Friday, June 21, 2002 1:03 PM
> To: Liaw, Andy
> Cc: 'Czerminski, Ryszard'; r-help at stat.math.ethz.ch
> Subject: Re: [R] problem with predict()
> 
> 
> "Liaw, Andy" <andy_liaw at merck.com> writes:
> 
> > You still don't get the point.  Please read Peter 
> Dalgaard's reply and the
> > help page for predict.lm carefully, and try to understand 
> the `Detail'
> > section.  See the example below:
> [snip]
> 
> > > This looks promissing; however I get an error:
> > > 
> > > > train <- data.frame(y=yr, x=xr)
> > > > test <- data.frame(y=ys, x=xs)
> > > > myfit <- lm(y ~ x, train)
> > > Error in eval(expr, envir, enclos) : Object "x" not found
> 
> But there's nothing wrong with that code as far as I can see?? I don't
> get an error from it:
> 
> > xr <- rnorm(10)
> > yr <- rnorm(10)
> > ys <- rnorm(5)
> > xs <- rnorm(5)
> > train <- data.frame(y=yr, x=xr)
> >  test <- data.frame(y=ys, x=xs)
> > myfit <- lm(y ~ x, train)
> > predict(myfit,test)
>           1           2           3           4           5 
> -0.03809295  0.11422384  0.35570765  0.55436954  0.22979523 
> 
> 
> Something must have gone wrong with the creation of "train".
> 
> -- 
>    O__  ---- Peter Dalgaard             Blegdamsvej 3  
>   c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
>  (*) \(*) -- University of Copenhagen   Denmark      Ph: 
> (+45) 35327918
> ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: 
> (+45) 35327907
> 

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