From: Greg Snow <Greg.Snow_at_imail.org>

Date: Wed, 09 Apr 2008 13:58:15 -0600

Date: Wed, 09 Apr 2008 13:58:15 -0600

It is still not clear what is your response (y) variable and exactly what is your predictor (x) variable(s).

If you have a separate vector of length 10 that is the response and you want to regress it with each of the 8 vectors mentioned, then here is one way to do that:

*> p<-1:80+rnorm(80)
**> dim(p)<-c(2,2,2,10)
**>
**> y <- 1:10
**>
**> my.data <- data.frame( y=rep(y,8), x=c(aperm(p,4:1)), g=gl(8,10) )
**>
**> library(nlme)
**>
*

> fits <- lmList( y ~ x | g, data=my.data )

*>
*

Now 'fits' is a list with the 8 regressions, you can access each regression with fits[[1]] and the like, or there are some summaries that you can get from the entire list.

Hope this helps,

-- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare greg.snow_at_imail.org (801) 408-8111Received on Wed 09 Apr 2008 - 20:05:03 GMT

> -----Original Message-----

> From: r-help-bounces_at_r-project.org> [mailto:r-help-bounces_at_r-project.org] On Behalf Of Costas Douvis> Sent: Wednesday, April 09, 2008 8:54 AM> To: Dimitris Rizopoulos; r-help_at_r-project.org> Subject: Re: [R] apply lm() for all the columns of a matrix>> Here's a simplified example>> p<-1:80+rnorm(80)> dim(p)<-c(2,2,2,10)>> We could say that the 4-d array p consists of 2*2*2 = 8> vectors of length 10. So what I'm asking for is a fast way to> perform a linear fit to all those vectors.>> I'm sorry if I'm causing you to have a headache with all> those dimensions :) Kostas>> > Well, could you provide a little bit more information> regarding what> > you are trying to do (e.g., reproducible example).> >> > Best,> > Dimitris> >> > ----> > Dimitris Rizopoulos> > Biostatistical Centre> > School of Public Health> > Catholic University of Leuven> >> > Address: Kapucijnenvoer 35, Leuven, Belgium> > Tel: +32/(0)16/336899> > Fax: +32/(0)16/337015> > Web: http://med.kuleuven.be/biostat/> > http://www.student.kuleuven.be/~m0390867/dimitris.htm> >> >> > ----- Original Message -----> > From: "Costas Douvis" <cdouvis_at_geol.uoa.gr>> > To: <r-help_at_r-project.org>; "Mark Leeds" <markleeds_at_verizon.net>;> > "Dimitris Rizopoulos" <dimitris.rizopoulos_at_med.kuleuven.be>> > Cc: "Chuck Cleland" <ccleland_at_optonline.net>> > Sent: Wednesday, April 09, 2008 3:44 PM> > Subject: Re: [R] apply lm() for all the columns of a matrix> >> >> >> Thank you all very much for replying. Of course you are absolutely> >> right but unfortunately I really deal with the case of a> 4-d matrix> >> so what you said does not apply. I should have specified> but being a> >> new R user I hadn't realized the difference between a> matrix and an> >> array.> >>> >> So please tell me if you know a fast way (not using a loop) to> >> perform a linear fit on all the vectors of the 4-th dimension of a> >> 4-d array.> >>> >> Thanks again> >> Kostas> >>> >>> If you have the same design matrix then you can specify a> matrix of> >>> responses in lm(), e.g.,> >>>> >>> Y <- matrix(rnorm(100*10), 100, 10)> >>> x <- rnorm(100)> >>>> >>> fit <- lm(Y ~ x)> >>> fit> >>> summary(fit)> >>>> >>>> >>> I hope it helps.> >>>> >>> Best,> >>> Dimitris> >>>> >>> ----> >>> Dimitris Rizopoulos> >>> Biostatistical Centre> >>> School of Public Health> >>> Catholic University of Leuven> >>>> >>> Address: Kapucijnenvoer 35, Leuven, Belgium> >>> Tel: +32/(0)16/336899> >>> Fax: +32/(0)16/337015> >>> Web: http://med.kuleuven.be/biostat/> >>> http://www.student.kuleuven.be/~m0390867/dimitris.htm> >>>> >>>> >>> ----- Original Message -----> >>> From: "Costas Douvis" <cdouvis_at_geol.uoa.gr>> >>> To: <r-help_at_r-project.org>> >>> Sent: Wednesday, April 09, 2008 12:55 PM> >>> Subject: [R] apply lm() for all the columns of a matrix> >>>> >>>> >>>> Hi all,> >>>>> >>>> My question is not really urgent. I can write a loop and> solve the> >>>> problem. But I know that I'll be in a similar situation> many more> >>>> times so it would be useful to find out the answer> >>>>> >>>> Is there a fast way to perform linear fit to all the> columns of a> >>>> matrix?> >>>> (or in the one dimension of a multi-dimensional array.)> I'm talking> >>>> about many single linear fits, not about a multiple fit.> I thought> >>>> that a combination of apply and lm would do it but I> can't make it> >>>> work> >>>>> >>>> Thank you> >>>> Kostas> >>>>> >>>>> >>>> --> >>>> Kostas Douvis> >>>> PhD Student> >>>> University of Athens - Department of Geography and Climatology> >>>> Academy of Athens - Research Centre for Atmospheric Physics and> >>>> Climatology> >>>> email: cdouvis_at_geol.uoa.gr> >>>> tel: +30-210-8832048> >>>>> >>>> ______________________________________________> >>>> R-help_at_r-project.org mailing list> >>>> https://stat.ethz.ch/mailman/listinfo/r-help> >>>> PLEASE do read the posting guide> >>>> http://www.R-project.org/posting-guide.html> >>>> and provide commented, minimal, self-contained,> reproducible code.> >>>>> >>>> >>>> >>> Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm> >>>> >>>> >>> >>> >> >> > Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm> >> >>>> --> Kostas Douvis> PhD Student> University of Athens - Department of Geography and> Climatology Academy of Athens - Research Centre for> Atmospheric Physics and Climatology> email: cdouvis_at_geol.uoa.gr> tel: +30-210-8832048>> ______________________________________________> R-help_at_r-project.org mailing list> https://stat.ethz.ch/mailman/listinfo/r-help> PLEASE do read the posting guide> http://www.R-project.org/posting-guide.html> and provide commented, minimal, self-contained, reproducible code.>

______________________________________________ R-help_at_r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.

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