Skip to content

package methods different behaviour R1.9.1 patched and R2.0.0

5 messages · Wolski, John Chambers

#
Hi!

Concerning different behaviour between 1.9.1 patched and:
R : Copyright 2004, The R Foundation for Statistical Computing
Version 2.0.0 Under development (unstable) (2004-09-06), ISBN 3-900051-07-0

Subtitle:
as(x,"vector"); x is of class "Massvector"; never enters setAs("Massvector","vector"...

The same code:

as(mvl[[1]],"vector")
causes under R1.9.1 to enter the function
setAs("Massvector","vector"
      ,function(from)
...

This never happens under R2.0.0.

The class "Massvector" contains class "Matrix"

A phenomenological description of what happens instead with R2.0.0 is

as(as(mvl[[1]],"Matrix"),"vector")

and its not what I would expect.

Is this an intended behaviour in R2.0.0?

/E
#
I had a typo in  the previous mail

"Massvector" extends "matrix" not "Matrix"


/E
#
It's not possible to tell what you're expecting or actually seeing from
this mail.   We need to see your code and the results, not your
interpretation of how as() is implemented.

Meanwhile, here's how a simple class that extends "matrix" works in
2.0.0

With the code:

 setClass("mat1", representation(id="character"), contains = "matrix")

 mm <- matrix(1:12,3,4)

 mmm <- new("mat1", mm, id = "numeric")

The result is:

R> as(mmm, "vector")
 [1]  1  2  3  4  5  6  7  8  9 10 11 12

Class "vector" is one of the basic R classes;  as explained in ?as, the
methods for these use the exisiting as.<class> functions, as.vector in
this case.  

The result is indeed the same as coercing mmm to "matrix" first and then
to vector

R> as(as(mmm, "matrix"), "vector")
 [1]  1  2  3  4  5  6  7  8  9 10 11 12

as one would expect, but the method for coercing class "mat1" does not
go through "matrix":

R> selectMethod("coerce", c("mat1", "vector"))
function (from, to, strict = TRUE) 
{
    value <- as.vector(from)
    if (strict) 
        attributes(value) <- NULL
    value
}
<environment: namespace:methods>
Wolski wrote:

  
    
#
Hello!

A simple example.

setClass("myclass"
,representation(info="character")
,contains="matrix"
)

setAs("myclass","vector"
,def=function(from)
{
	print("enters?")
	to<-summary(from[,1])
	to<-as.vector(to)
	to
}
)

#init
dd<-matrix(1:6,nrow=2)
rownames(dd)<-c("a","b")
tt<-new("myclass",dd)

class(tt)
as(tt,"vector")
summary(dd[,1])

What I expect.
R : Copyright 2004, The R Foundation for Statistical Computing
Version 1.9.1 Patched (2004-08-30), ISBN 3-900051-00-3
[1] "myclass"
attr(,"package")
[1] ".GlobalEnv"
[1] "enters?"
[1] 1.00 1.25 1.50 1.50 1.75 2.00
Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
   1.00    1.25    1.50    1.50    1.75    2.00 


R : Copyright 2004, The R Foundation for Statistical Computing
Version 2.0.0 Under development (unstable) (2004-09-06), ISBN 3-900051-07-0
[1] "myclass"
attr(,"package")
[1] ".GlobalEnv"
[1] 1 2 3 4 5 6
Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
   1.00    1.25    1.50    1.50    1.75    2.00 

Yours
Eryk




*********** REPLY SEPARATOR  ***********
On 9/7/2004 at 10:34 AM John Chambers wrote:

            
Dipl. bio-chem. Witold Eryk Wolski             @         MPI-Moleculare Genetic   
Ihnestrasse 63-73 14195 Berlin                'v'    
tel: 0049-30-83875219                        /   \       
mail: witek96@users.sourceforge.net        ---W-W----    http://www.molgen.mpg.de/~wolski 
      wolski@molgen.mpg.de
#
Wolski wrote:
Good example.  Thanks.  This was a bug in setAs() that did not set the
coerce method in the case of overriding the default method for a
contained class.  There should be a fix installed in a day or two.