[R-pkg-devel] Linking an R package to the Python library

[Johannes Ranke]

Bruce,

maybe you want to also have a look at PythonInR, which solves a similar, if 
not the same, problem

https://bitbucket.org/Floooo/pythoninr/

Johannes

Am Montag, 29. Februar 2016, 13:01:06 schrieb Bruce Hoff:
> I am trying to create a self-contained R package wrapping Python that works
> cross platform and have not been able to do this on Windows.  There is
> already an R package which calls Python, requiring Python to be installed
> on the target machine: https://github.com/cjgb/rPython-win.  When the R
> package is built it successfully links to the resident Python dll.
> 
> I retrieved the Python source code plus associated Visual Studio projects
> as described here: https://docs.python.org/devguide/setup.html  I ran the
> Python 3.6 build and verified that rPython-win can link to the generated
> dll, as expected.  In order to make a portable, self-contained R package, I
> changed the build to create a _static_ Python library as described in the
> file PCbuild\readme.txt.  This creates a 31MB file "python36.lib" but when
> I try to build the rPython-win package under R i386 (and using the latest
> RTools) I get:
> 
> gcc -m32 -shared -s -static-libgcc -o rPython.dll tmp.def pycall.o
> -LC:/cpython/PCbuild/win32 -lpython3stub -lpython36
> -Ld:/RCompile/r-compiling/local/local323/lib/i386
> -Ld:/RCompile/r-compiling/local/local323/lib
> -LC:/PROGRA~1/R/R-32~1.3/bin/i386 -lR
> C:/cpython/PCbuild/win32/python36.lib: *error adding symbols: File format
> not recognized*
> collect2.exe: error: ld returned 1 exit status
> no DLL was created
> ERROR: compilation failed for package 'rPython'
> 
> I see some mention of the link error here:
> https://sourceware.org/bugzilla/show_bug.cgi?id=17910
> It looks like a related bug was in binutils 2.25 on 2/27/2015.  It seems
> like the fix would have made it into Rtools 3.3 since:
> 1) this page suggests that the aforementioned was resolved before the
> latest release of binutils, 2.25.1, 9/15/2015:
> https://sourceforge.net/projects/mingw/files/MinGW/Base/binutils/
> 2) Installing Rtools 3.3, one can see that the binaries which are part of
> binutils (like ld.exe) are dated 9/22/2015.
> 
> I don't know if MinGW is 'buggy', if I'm doing something wrong, and/or what
> to do to fix the link error.
> 
> Is there anyone on this list with experience linking an R package to a
> static library built on Windows using Visual Studio?
> 
> Any suggestions are appreciated!
> 
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> 
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PD Dr. Johannes Ranke
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