[R] On-demand importing of a package

Joshua Wiley jwiley.psych at gmail.com
Tue Nov 22 21:31:59 CET 2011

Hi Gábor,

You could import rowSums.  This will not fully attach Matrix.  I am
not sure there is a really good solution for what you want to do.  To
fully use and validate your package, Matrix appears to be required.
This is different from simply, for example, enhancing the Matrix

You could just write the functions assuming matrix is there, make sure
the examples are marked don't run, and tell users if they want to use
them, they need to load Matrix first.  I do this with OpenMx in my



On Tue, Nov 22, 2011 at 12:16 PM, Gábor Csárdi <csardi at rmki.kfki.hu> wrote:
> Dear All,
> in some functions of my package, I use the Matrix S4 class, as defined
> in the Matrix package.
> I don't want to depend on Matrix, however, because my package is
> perfectly fine without Matrix, most of the functionality does not need
> Matrix. Matrix is so included in the 'Suggests' line.
> I load Matrix via require(), from the functions that really need it.
> This mostly works fine, but I have an issue now that I cannot sort
> out.
> If I define a function like this in my package:
> f <- function() {
>  require(Matrix)
>  res <- sparseMatrix(dims=c(5, 5), i=1:5, j=1:5, x=1:5)
>  y <- rowSums(res)
>  res / y
> }
> then calling it from the R prompt I get
> Error in rowSums(res) : 'x' must be an array of at least two dimensions
> which basically means that the rowSums() in the base package is
> called, not the S4 generic in the Matrix package. Why is that?
> Is there any way to work around this problem, without depending on Matrix?
> I am doing this on R 2.14.0, x86_64-apple-darwin9.8.0.
> Thank You, Best Regards,
> Gabor
> --
> Gabor Csardi <csardi at rmki.kfki.hu>     MTA KFKI RMKI
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Joshua Wiley
Ph.D. Student, Health Psychology
Programmer Analyst II, ATS Statistical Consulting Group
University of California, Los Angeles

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