On 24/08/2019 10:36 a.m., Kevin Coombes wrote:
Hi,
I've been building a package and hit a NAMESPACE issue that took a while
to resolve.
My package implements a (new) generic function, and the method for a
package in the class calls the "smoothScatter" function from the
"graphics" package. I could build and install the package successfully,
and when I used the generic function, it worked just fine.
However, when I ran "R CMD check --as-cran", it threw an error from both
the examples in man pages and a test script. Specifically, the error was
"package KernSmooth not available". I eventually worked around this
problem by changing the DESCRIPTION file to "IMPORT KernSmooth" (even
though I didn't have to actually import anything in "NAMESPACE").
The underlying issue appears to be that
graphics::smoothScatter
calls a non-exported function from "grDevices"
grDevices:::.smoothScatterCalcDensity
which in turn calls an explicitly qualified function from "KernSmooth"
KernSmooth::bkde2D
That looks like a bug in grDevices. If it suggests KernSmooth, it
should explicitly check whether it is installed before calling a
function from it.
To complicate matters
graphics IMPORTs grDevices
but
grDevices only SUGGESTs KernSmooth.
Since my package already IMPORTed the graphics package and had
importFrom("graphics", "smoothScatter")
in the NAMESPACE, I was surprised that I had to track back through the
code to find this dependency and had to make it explicitly known within
the interface to my package.
Is there something else my package should do? Or should "grDevices"
actually IMPORT "KernSmooth"?
It could import it, or it could put in a check and a workaround if it is
not found.
Now that you know about this bug, you could work around it by suggesting
KernSmooth, and not calling graphics::smoothScatter unless KernSmooth is
available.
Duncan Murdoch
Best,
Kevin
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