R help - Jul 2006 - conflict of package "Matrix" and summary of lme object

After loading the package "Matrix" (version 0.995-12), using the
summary
function with an lme (package nlme version 3.1-75) object results in an 
error message saying

Fehler in dim(x) : kein Slot des Namens "Dim" f?r dieses Objekt der 
Klasse "correlation"

(translated: 'Error in dim(x) : no slot of the name "Dim" for this
object of class "correlation")'.

Without loading "Matrix" this error message does not occur.

Any ideas?

------------------------------
R version: 2.3.1 Patched (2006-06-21 r38367)
Operating system: Windows XP (5.1 (Build 2600))
CPU: Pentium Model 2 Stepping 9

*************************************************
Dr. Dirk Enzmann
Institute of Criminal Sciences
Dept. of Criminology
Edmund-Siemers-Allee 1
D-20146 Hamburg
Germany

phone: +49-(0)40-42838.7498 (office)
        +49-(0)40-42838.4591 (Billon)
fax:   +49-(0)40-42838.2344
email: dirk.enzmann at uni-hamburg.de
www: 
http://www2.jura.uni-hamburg.de/instkrim/kriminologie/Mitarbeiter/Enzmann/Enzmann.html

>>>>> "Dirk" == Dirk Enzmann <dirk.enzmann at
uni-hamburg.de>
>>>>>     on Mon, 24 Jul 2006 13:55:44 +0200 writes:
    Dirk> After loading the package "Matrix" (version 0.995-12),
    Dirk> using the summary function with an lme (package nlme
    Dirk> version 3.1-75) object results in an error message
    Dirk> saying

    Dirk> Fehler in dim(x) : kein Slot des Namens "Dim" f?r
    Dirk> dieses Objekt der Klasse "correlation"

    Dirk> (translated: 'Error in dim(x) : no slot of the name
    Dirk> "Dim" for this object of class
"correlation")'.

    Dirk> Without loading "Matrix" this error message does not
    Dirk> occur.

    Dirk> Any ideas?

Yes. Thank you for the report.
The error happens when PRINTing a summary.lme object, 
i.e.,
	ssl <- summary(<lme> )  ## works fine
	ssl                     ##-> gives the error

The short answer:  
   Don't use 'Matrix' together with 'nlme'  for the time
being
   (but rather use 'lme4' and lmer() if possible)

A long answer:

The problem happens because
'Matrix' defines a (S4) class "correlation"  (which inherits
from
"dpoMatrix").  Hence  dim( <correlation> ) is accessing the
'Dim' slot of the <correlation> object --- which obviously
must fail for that part of a  "summary.lme" object which is not
a proper S4 object at all.

Here is reproducible example of showing the problem without even
doing an nlme related thing: 

   > x <- round(cor(matrix(rnorm(100), 20,5)),2); class(x) <-
"correlation" ; x
	 [,1]  [,2]  [,3]  [,4]  [,5]
   [1,]  1.00 -0.29 -0.07 -0.11  0.03
   [2,] -0.29  1.00  0.10 -0.02  0.20
   [3,] -0.07  0.10  1.00  0.05  0.13
   [4,] -0.11 -0.02  0.05  1.00 -0.21
   [5,]  0.03  0.20  0.13 -0.21  1.00
   attr(,"class")
   [1] "correlation"
   > dim(x)
   [1] 5 5
   > library(Matrix)
   Loading required package: lattice
   > dim(x)
   Error in dim(x) : no slot of name "Dim" for this object of class
"correlation"
   > dim
   .Primitive("dim")
   > showMethods(dim)

   Function "dim":
    x = "ANY"
    x = "Matrix"
    x = "correlation"
       (inherited from x = "Matrix")
   > showClass("correlation")

   Slots:

   Name:         sd         x       Dim  Dimnames      uplo   factors
   Class:   numeric   numeric   integer      list character      list

   Extends: 
   Class "dpoMatrix", directly
   Class "dsyMatrix", by class "dpoMatrix"
   Class "ddenseMatrix", by class "dpoMatrix"
   Class "symmetricMatrix", by class "dpoMatrix"
   Class "dMatrix", by class "dpoMatrix"
   Class "denseMatrix", by class "dpoMatrix"
   Class "Matrix", by class "dpoMatrix"
   Class "Matrix", by class "dpoMatrix"
   Class "compMatrix", by class "dpoMatrix"
   Class "Matrix", by class "dpoMatrix"
   > 


A workaround -- not for you but the authors of 'Matrix' and/or
'nlme' --
is for one of the two packages to call the class differently.
At the moment, I tend to do the change in 'nlme', since there,
the "correlation" class has been almost entirely hidden from the user.

A workaround for you:  Redefine print.summary.lme, e.g., by
commenting the line 
    class(corr) <- "correlation"

Regards,
Martin