[R] small problem with predict

[Anne]

Thanks Petr,

That was indeed the root of the problem! 

Have a nice week end

Anne


In fact it must be the problem
----- Original Message ----- 
From: "Petr Pikal" <petr.pikal at precheza.cz>
To: <r-help at stat.math.ethz.ch>; "Anne" <anne.piotet at urbanet.ch>
Sent: Friday, July 16, 2004 1:39 PM
Subject: Re: [R] small problem with predict


> 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
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> > > ______________________________________________
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> > > PLEASE do read the posting guide!
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> > 
> > Petr Pikal
> > petr.pikal at precheza.cz
> > 
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
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> > PLEASE do read the posting guide!
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> 
> Petr Pikal
> petr.pikal at precheza.cz
> 
>