[R] warning creating an as.array method in a package

[Michael Friendly]

On 11/30/2010 5:59 PM, David Winsemius wrote:
>
> I'm guessing from this behavior on my system that it may be Matrix.
>
>  > showMethods(as.array)
> Function: as.array (package base)
> x="ANY"
> x="Matrix"
>
I'm still perplexed by this.  Running R CMD install gives this warning:
** testing if installed package can be loaded
Warning: found an S4 version of 'as.array' so it has not been imported 
correctly

Yet, in a freshly initialized R console, I get:
 > methods("as.array")
[1] as.array.default
 > showMethods("as.array")

Function "as.array":
  <not a generic function>

Then, I load Matrix:

 > library(Matrix)
Loading required package: lattice

Attaching package: 'Matrix'

The following object(s) are masked from 'package:base':

     det

 > showMethods("as.array")
Function: as.array (package base)
x="ANY"
x="Matrix"

Under ?methods the Note says

Functions can have both S3 and S4 methods, and function showMethods will 
list the S4 methods (possibly none).

Does the warning mean that I cannot (or should not) have an S3 as.array 
method in a package?
The method works in my context, but the warning will create problems 
when I submit to CRAN, so I would rather avoid it.


-- 
Michael Friendly     Email: friendly AT yorku DOT ca
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