error using R package brms - r

Question

I would like to use the R package brms, but I get an error that I do not manage to interpret. It might have to do with Rtools, which is however installed on my computer.
This is an example from the brms package:
fit1 <- brm(count ~ log_Age_c + log_Base4_c * Trt_c
+ (1|patient) + (1|visit) + (1|obs),
data = epilepsy, family = poisson(),
prior = c(set_prior("student_t(5,0,10)", class = "b"),
set_prior("cauchy(0,2)", class = "sd")))
And this is the error I get:
Error in compileCode(f, code, language = language, verbose = verbose) :
Compilation ERROR, function(s)/method(s) not created!
c:/Rtools/mingw_64/bin/g++: not found
make: *** [file202834c75e9.o] Error 127
Warning message:
l'exécution de la commande 'make -f "C:/PROGRA~1/R/R-33~1.0/etc/x64/Makeconf" -f "C:/PROGRA~1/R/R-33~1.0/share/make/winshlib.mk" SHLIB_LDFLAGS='$(SHLIB_CXXLDFLAGS)' SHLIB_LD='$(SHLIB_CXXLD)' SHLIB="file202834c75e9.dll" WIN=64 TCLBIN=64 OBJECTS="file202834c75e9.o"' renvoie un statut 2
In addition: Warning message:
running command 'C:/PROGRA~1/R/R-33~1.0/bin/x64/R CMD SHLIB file202834c75e9.cpp 2> file202834c75e9.cpp.err.txt' had status 1
Thanks for your help

Answer 1

Indeed, it is a problem with Rtools. What does system("g++ -v") give you? If it is status 127, Rtools cannot be found by R. Most likely, you haven't checked the box during Rtools installation where you were asked to amend the system path. I suggest that you unintall Rtools and install it again making sure to check the box. Please also verify that you are using the correct version of Rtools compatible with your R version.

Answer 2

I had a similar problem with my installation of rstan. The problem occurred with RTools33. Installing RTools34 seemed to fix the problem, although I now get the following warning:
In find_rtools() :
WARNING: Rtools 3.4 found on the path at c:/Rtools is not compatible with R 3.3.1.
Please download and install Rtools 3.3 from http://cran.r-project.org/bin/windows/Rtools/, remove the incompatible version from your PATH, then run find_rtools().
So far this warning appears benign.

Answer 3

If none of the other answers solve this issue, go into your R distribution and open
R-{version}\etc\x64\Makeconf
and change BINPREF on line 19 to whatever the path to your mingw_64\bin directory is.

Answer 4

To fix this error:" c:/Rtools/mingw_64/bin/g++: not found" I located RBuildTools folder on the C: drive, found the g++ file in the bin folder, copied the mingw_64 folder (or wherever your g++ file is located), created an Rtools folder on C: and pasted the mingw_64 folder. This will create the C:/Rtools/mingw_64/bin/ path you need to compile R code using the stan( ) function.

Answer 5

I followed the rStan wiki here on Windows Configuration.
Also instead of hacking Makevars in c:\ you can create your personal by following the instruction here.
In my %HOM%\.R\Makevars.win64 file I have
CXXFLAGS=-O3 -mtune=native -march=native -Wno-unused-variable -Wno-unused-function
BINPREF="H:/RTools/mingw_64/bin/"
This resolved my issue.