[R] small problem with predict
Petr Pikal
petr.pikal at precheza.cz
Fri Jul 16 13:39:29 CEST 2004
Hi Ann
As I read your code mode closely, I suspect that there could be
another variables x1 and x2 somewhere in your search path which
led to the error.
With fresh R session without any data this works as expected
dold<-data.frame(x1=rnorm(10),x2=5*rnorm(10))
y<-1:10
predict(lm(y~x1+x2,dold),dn,se.fit=T)
Cheers
Petr
On 16 Jul 2004 at 13:19, Petr Pikal wrote:
> Hi
>
> On 16 Jul 2004 at 12:38, Anne wrote:
>
> > hello to all!
> >
> > I have a small problem wit predict() for lm
> >
> > Let's say I have predictors x1 and x2, response y
> >
> > I want to predict for a new ds say
> > dn<-data.frame(x1=
> > seq(min(x1),max(x1),length=10),x2=rep(median(x2),10))
> >
> > predict(lm(y~x1+x2),dn,se.fit=T)
> >
> >
> > Error message
> > > Error: variables 'x1', 'x2' were specified differently from the
> > > fit
>
> AFAIK predixt require to be fed by dataframe in which the
> variables has the same names as was in lm() call. Either call lm()
> with variables named "x1" and "x2" or build the dataframe "dn" with
> names identical as are names in lm() call
>
> Cheers
> Petr
>
>
> >
> > (I looked in the help and found the example
> >
> > x <- rnorm(15)
> > y <- x + rnorm(15)
> > new <- data.frame(x = seq(-3, 3, 0.5))
> > predict(lm(y ~ x), new, se.fit = TRUE)
> >
> > where is the difference?)
> >
> >
> > Anne
> >
> > ----------------------------------------------------
> > Anne Piotet
> > Tel: +41 79 359 83 32 (mobile)
> > Email: anne.piotet at m-td.com
> > ---------------------------------------------------
> > M-TD Modelling and Technology Development
> > PSE-C
> > CH-1015 Lausanne
> > Switzerland
> > Tel: +41 21 693 83 98
> > Fax: +41 21 646 41 33
> > --------------------------------------------------
> >
> > [[alternative HTML version deleted]]
> >
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>
> Petr Pikal
> petr.pikal at precheza.cz
>
> ______________________________________________
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Petr Pikal
petr.pikal at precheza.cz
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