[R-pkg-devel] Warning that are Unintentionally OS-Specific (Maybe Bug in warning?)

Hi Bill,

   The problem is not with the warning() function but with your if()
test that triggers the warning. It probably has something to do with
slight differences in rounding. I suggest you use debug() or browser()
on each platform to see why your condition is TRUE or FALSE.

   Cheers,
   -- Fran?ois

On Wed, Jul 20, 2016 at 2:42 PM, Bill Denney <bill at denney.ws> wrote:

Hi,

I'm developing the PKNCA package, and I've got an odd difference between
warning behavior on different operating systems that I can't figure out.

When I run the following code on Windows 10 (with R 3.3.0), I get the
following warning:

library(PKNCA)
source("https://raw.githubusercontent.com/billdenney/pknca/master/tests/testthat/generate.data.R")
tmpconc <- generate.conc(2, 1, 0:24)
tmpconc$conc <- 0
tmpdose <- generate.dose(tmpconc)
myconc <- PKNCAconc(tmpconc, conc~time|treatment+ID)
mydose <- PKNCAdose(tmpdose, dose~time|treatment+ID)
mydata <- PKNCAdata(myconc, mydose)
myresult <- pk.nca(mydata)

Warning messages:
1: In pk.calc.half.life(conc = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  :
   Too few points for half-life calculation (min.hl.points=3 with only 0
points)
2: In pk.calc.half.life(conc = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  :
   Too few points for half-life calculation (min.hl.points=3 with only 0
points)

When I run the code on Linux (Ubuntu 16.04 with R 3.3.1), I do not get a
warning.  When I run the code on Linux after "options(warn=1)", I get the
warning.  I have confirmed that the same code path is taken in both Windows
and Linux by simply inserting a print statement next to the warning.  The
actual warning code is:

     warning(sprintf(
       "Too few points for half-life calculation (min.hl.points=%g with only
%g points)",
       min.hl.points, nrow(dfK)))

This platform inconsistency is causing issues with my package because the
package expects the warnings, and the user should know about the warnings.
I've got test cases expecting the warnings, and they fail everywhere but
Windows (https://cran.r-project.org/web/checks/check_results_PKNCA.html).

Does anyone have an idea why warnings may behave differently on Windows
compared to non-Windows platforms?  Is this a bug in R somewhere?  (I've not
been able to make a simpler example that triggers the issue, unfortunately.)

Thanks,

Bill