R help - May 2011 - what happens when I store linear models in an array?

I've got a bunch of similar datasets, all of which I've fit to linear
models.  I'd like to easily create arrays of a specific parameter from each
linear model (e.g., all of the intercepts in one array).  I figured I'd put
the model objects into an array, and then (somehow) I could easily create
corresponding arrays of intercepts or residuals or whatever, but I can't the
parameters back out.

 

Right now I've stored the model objects in a 2-D
array:
> lms.ASP <- array(list(), c(3,4))
 

Then I fill the array element-by-element:
> surf105.lm. ASP <- lm(ASP ~ time)
> lms.ASP[1,1] <- list(surf105.lm.ASP)
 

Something is successfully being stored in the array:
> test <- lms.tx.ASP[1,1]
> test
[[1]]
Call:
lm(formula = ASP ~ time)
Coefficients:
     (Intercept)  elapsed.time..hr  
     0.430732          0.004073  

 

But I can't seem to call extraction functions on the linear
models:
> fitted(lms.ASP[1,1])
NULL

 

It seems like something less than the actual linear model object is being
stored in the array, but I don't understand what's happening, or how to
easily batch-extract parameters of linear models.  Any advice?

 

 

____________________________________

Andrew D. Steen, Ph.D.

Center for Geomicrobiology, Aarhus University

Ny Munkegade 114
DK-8000 Aarhus C
Denmark
Tel: +45 8942 3241
Fax: +45 8942 2722

andrew.steen@biology.au.dk

 


	[[alternative HTML version deleted]]

Hi Andrew,

try

fitted(lms.ASP[1,1][[1]])

Cheers

Andrew

On Wed, May 04, 2011 at 01:49:45PM +0200, Andrew D. Steen
wrote:
> I've got a bunch of similar datasets, all of which I've fit to
linear
> models.  I'd like to easily create arrays of a specific parameter from
each
> linear model (e.g., all of the intercepts in one array).  I figured I'd
put
> the model objects into an array, and then (somehow) I could easily create
> corresponding arrays of intercepts or residuals or whatever, but I
can't the
> parameters back out.
> 
>  
> 
> Right now I've stored the model objects in a 2-D array:
> > lms.ASP <- array(list(), c(3,4))
> 
>  
> 
> Then I fill the array element-by-element:
> > surf105.lm. ASP <- lm(ASP ~ time)
> > lms.ASP[1,1] <- list(surf105.lm.ASP)
> 
>  
> 
> Something is successfully being stored in the array:
> > test <- lms.tx.ASP[1,1]
> > test
> [[1]]
> Call:
> lm(formula = ASP ~ time)
> Coefficients:
>      (Intercept)  elapsed.time..hr  
>      0.430732          0.004073  
> 
>  
> 
> But I can't seem to call extraction functions on the linear models:
> > fitted(lms.ASP[1,1])
> NULL
> 
>  
> 
> It seems like something less than the actual linear model object is being
> stored in the array, but I don't understand what's happening, or
how to
> easily batch-extract parameters of linear models.  Any advice?
> 
>  
> 
>  
> 
> ____________________________________
> 
> Andrew D. Steen, Ph.D.
> 
> Center for Geomicrobiology, Aarhus University
> 
> Ny Munkegade 114
> DK-8000 Aarhus C
> Denmark
> Tel: +45 8942 3241
> Fax: +45 8942 2722
> 
> andrew.steen at biology.au.dk
> 
>  
> 
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.
-- 
Andrew Robinson  
Program Manager, ACERA 
Department of Mathematics and Statistics            Tel: +61-3-8344-6410
University of Melbourne, VIC 3010 Australia               (prefer email)
http://www.ms.unimelb.edu.au/~andrewpr              Fax: +61-3-8344-4599
http://www.acera.unimelb.edu.au/

Forest Analytics with R (Springer, 2011) 
http://www.ms.unimelb.edu.au/FAwR/
Introduction to Scientific Programming and Simulation using R (CRC, 2009): 
http://www.ms.unimelb.edu.au/spuRs/

On May 4, 2011, at 4:49 AM, Andrew D. Steen wrote:
> I've got a bunch of similar datasets, all of which I've fit to
linear
> models.  I'd like to easily create arrays of a specific parameter  
> from each
> linear model (e.g., all of the intercepts in one array).  I figured  
> I'd put
> the model objects into an array, and then (somehow) I could easily  
> create
> corresponding arrays of intercepts or residuals or whatever, but I  
> can't the
> parameters back out.
>
> Right now I've stored the model objects in a 2-D array:
>> lms.ASP <- array(list(), c(3,4))
>
> Then I fill the array element-by-element:
>> surf105.lm. ASP <- lm(ASP ~ time)
>> lms.ASP[1,1] <- list(surf105.lm.ASP)
>
> Something is successfully being stored in the array:
>> test <- lms.tx.ASP[1,1]
>> test
> [[1]]
> Call:
> lm(formula = ASP ~ time)
> Coefficients:
>     (Intercept)  elapsed.time..hr
>     0.430732          0.004073
>
> But I can't seem to call extraction functions on the linear models:
>> fitted(lms.ASP[1,1])
> NUL
>
> It seems like something less than the actual linear model object is  
> being
> stored in the array, but I don't understand what's happening, or
how
> to
> easily batch-extract parameters of linear models.  Any advice?
>
The problem is that the "[" function is returning a sublist from that
array of lists, which is still a list. You wanted the contents of the  
first (and only) element of that list and  Andrew Robinson offered you  
the solution.

-- 

David Winsemius, MD
Heritage Laboratories
West Hartford, CT