RDataFrame in external program

ROOT
1

Dear Experts,

I would like to use the concept of RDataFrame in my C++ standalone program, you see here a simplified version of the program.cxx and CMakeLists.txt

#include "ROOT/RDataFrame.hxx"
#include "ROOT/RVec.hxx"
#include "ROOT/RDF/RInterface.hxx"

#include "TFile.h"

int main() {
	TFile *f = new TFile("file.root");
	ROOT::RDataFrame df("tree", "file.root");
	//f->ls();
}

and

cmake_minimum_required(VERSION 3.0 FATAL_ERROR)
project(program)

list(APPEND CMAKE_PREFIX_PATH $ENV{ROOTSYS})
find_package(ROOT REQUIRED)

include(${ROOT_USE_FILE})
#include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)

add_executable(program program.cxx)
target_link_libraries(program "${ROOT_LIBRARIES}")
set_property(TARGET program PROPERTY CXX_STANDARD 11)

and I always get this error:

/usr/bin/ld: CMakeFiles/program.dir/program.cxx.o: in function `main':
program.cxx:(.text+0x134): undefined reference to `ROOT::RDataFrame::RDataFrame(std::experimental::__ROOT::basic_string_view<char, std::char_traits<char> >, std::experimental::__ROOT::basic_string_view<char, std::char_traits<char> >, std::vector<std::string, std::allocator<std::string> > const&)'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/program.dir/build.make:105: program] Error 1
make[1]: *** [CMakeFiles/Makefile2:76: CMakeFiles/program.dir/all] Error 2
make: *** [Makefile:84: all] Error 2

What is going on?

Thank you very much in advance,

ROOT Version: 6.18
Platform: Ubuntu
Compiler: 8.33

2

Hi,
It looks like libROOTDataFrame is not being liked to your program. Does ${ROOT_LIBRARIES} contain ROOTDataFrame? Alternatively, can you try adding ROOTDataFrame or ROOT::ROOTDataFrame explicitly to the target_link_libraries?

Cheers,
Enrico

3

No, that’s not it, I think that there is a mismatch in C++ standards being used. Just remove the last line from your CMakeLists.txt in which you set the CXX_STANDARD property. The ROOT libraries already export this property. You have to ensure that your code is compiled with the same stardard as ROOT or it will not work. Cheers,

4

Hi,

Thank you for your reply. It seems that the problem I had is related to the other library (PyTorch) that I want to compile it with root. That if I have this small program

#include "ROOT/RDataFrame.hxx"
#include "ROOT/RVec.hxx"
#include "ROOT/RDF/RInterface.hxx"
#include "TFile.h"

#include <torch/torch.h>
int main() {
	TFile *f = new TFile("file.root");
	ROOT::RDataFrame df("tree", "file.root");
	//f->ls();
        torch::Tensor tensor = torch::rand({2, 3});
        std::cout << std::endl << tensor << std::endl;
        return 0;
}

and CMakeLists.txt:

cmake_minimum_required(VERSION 3.0 FATAL_ERROR)
project(program)

list(APPEND CMAKE_PREFIX_PATH $ENV{ROOTSYS} "path/to/libtorch")
find_package(ROOT REQUIRED)
find_package(Torch REQUIRED)

include(${ROOT_USE_FILE})

add_executable(program program.cxx)
target_link_libraries(program "${ROOT_LIBRARIES}" "${Torch_LIBRARIES}")
set_property(TARGET program PROPERTY CXX_STANDARD 11)

That NEVER compiled, there is always a problem in the linker.

libtorch can be download from here

5

Everything linked with ROOT must use the same C++ standard as ROOT, if ROOT is compiled with C++11, then it’s ok to have what you have above, otherwise, you have to recompile either ROOT or PyTorch to make it work if they are using different versions of the C++ standard. Cheers,