From: Costas Douvis <cdouvis_at_geol.uoa.gr>

Date: Wed, 09 Apr 2008 17:54:26 +0300 (EEST)

Date: Wed, 09 Apr 2008 17:54:26 +0300 (EEST)

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.Received on Wed 09 Apr 2008 - 15:17:15 GMT

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