[R] Abstract classes

Sharpie chuck at sharpsteen.net
Thu Mar 25 17:02:10 CET 2010

Albert-Jan Roskam wrote:
> Hi R lovers,
> I'm looking for more information about, and implementations of abstract
> classes. After reading "Head First Design Patterns" (O'Reilly). I want to
> know whether I could use this to build an interface, i.e. a placeholder
> for all possible methods in the underlying subclasses. The final goal is
> to end up with a more flexible/extensible design than could be achieved
> with inheritance and polymorphism.
> I installed the 'sp' package, because I read that the Spatial Class is an
> abstract class, but I don't know where to look for the file where that
> class lives. I tried, among others, the files in:
> R/i486-pc-linux-gnu-library/2.9/sp/R.
> Cheers!!
> Albert-Jan

It looks like you were looking in the R library where R stores sp after
installing it- the problem with this is that R converts all the code to a
binary format and stores it in a single file.  You want to download the
source tarball from CRAN:


Untar it and look in the R directory of the resulting folder.  You will see
a file called Class-Spatial.R that contains the S4 class definition.

Another good study in S4 inheritance is the Matrix package which is now
included in the R core.  You can download it's source from:


Look at the file called AllClass.R

Hope this helps!


Charlie Sharpsteen
Undergraduate-- Environmental Resources Engineering
Humboldt State University
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