[R-pkg-devel] Getting summary.glm to use Matrix::chol2inv

[Mark Donoghoe]

Hi,

I am trying to implement a new method for glm2 which allows the use of
the Matrix package to work with large data.

I have added Matrix to Suggests, and when the new method is requested,
the following check is performed:

if (!requireNamespace("Matrix", quietly = TRUE)) {
      stop("Package \"Matrix\" must be installed to use method =
\"glm.fit2.Matrix\".",
           call. = FALSE)
    }

This works fine. However, I would like the user to be able to use
summary.glm on the fitted object x, and it effectively calls
chol2inv(x$qr$qr[1:p,1:p]), which fails if x$qr$qr is not a (small m)
matrix:

Error in chol2inv(Qr$qr[p1, p1, drop = FALSE]) :
  'a' must be a numeric matrix

I can return the matrix version of x$qr$qr, but this can be quite
large and ideally I would like to return the Matrix version, and have
summary.glm automatically call the Matrix version of chol2inv.

I imagine this would require changing the search path, which I
understand is not recommended, but I am not even sure how to go about
it, or if there is another solution that wouldn't require a custom
version of summary.glm. I also tried attachNamespace in a similar code
block when glm.fit2.Matrix is called, but that did not work.

Thanks in advance for any suggestions.

Mark