How to call openAI Gym from C++?

[Thanh-Binh]

Hi,
Thanks for sharing your interesting works.
Do you plan to implement other environments lien LunaLander or Donkeycar?
How can I call openAI Gym (Python version) directly from my c++ main()?

Thanks

[anhydrous99]

Hello and sorry for getting back to you after so long,

Unfortunately, I don't enough time to figure out how box2d, the library that Gym uses for LunarLandar, works to implement it. Your welcome to help out with that.

Anyway, if you wanted to use the project directly from C++, you can make a fork replace the CMakeLists.txt script that builds this project with something like

cmake_minimum_required(VERSION 3.16)
project(cppgym)

set(CMAKE_CXX_STANDARD 17)

include(CheckCXXSymbolExists)
check_cxx_symbol_exists(sincosf "math.h" HAVE_SINCOSF)
if (HAVE_SINCOSF)
    add_definitions(-DHAVE_SINCOSF)
endif ()


add_library(cppgym
        src/EnvCPP.h
        src/EnvCPP.cpp
        src/ClassicControl/ClassicEnvCPP.h
        src/ClassicControl/CartPole/CartPoleCPP.h
        src/ClassicControl/CartPole/CartPoleCPP.cpp)
        src/ClassicControl/MountainCar/MountainCarCPP.h
        src/ClassicControl/MountainCar/MountainCarCPP.cpp)
        src/ClassicControl/MountainCarContinuous/MountainCarContinuousCPP.h
        src/ClassicControl/MountainCarContinuous/MountainCarContinuousCPP.cpp)
        src/ClassicControl/Pendulum/PendulumCPP.h
        src/ClassicControl/Pendulum/PendulumCPP.cpp)
        src/ClassicControl/Acrobot/AcrobotCPP.h
        src/ClassicControl/Acrobot/AcrobotCPP.cpp)
        src/ToyText/BlackJack/BlackJackCPP.h
        src/ToyText/BlackJack/BlackJackCPP.cpp)
        src/ToyText/HotterColder/HotterColderCPP.h
        src/ToyText/HotterColder/HotterColderCPP.cpp)

Then add that fork as a submodule to your git project and in your CMakeList script for your main project simply have:

add_subdirectory(<path to cppgym submodule>)

add_executable(main_project main.cpp)
target_link_libraries(main_project cppgym)

note: I haven't tested these so you might need to tweak them

bests

[Thanh-Binh]

thanks ans sorry for my too late to go back to this topic.
in principle, I can compile it, and try to write a main.cpp for working with CartPole:

#include "ClassicControl/CartPole/CartPoleCPP.h"
using namespace std;
int main()
{
	int n_episodes = 100; // Number of episodes
	CartPoleCPP env;
	for (auto i = 0; i < n_episodes; ++i)
	{
    std::array<float, 4> state = env.reset(); // Reset the environment (as OpenAI's gym)
    float total_reward = 0.0;
    while (1)
		{
			// How can I get action from Gym???
			//action = env.action_space.sample(); // Sample from the action space (as OpenAI's gym)
			// next_state, reward, done, _ 
			std::tuple<std::array<float, 4>, float, bool> data = env.step(action); // Step the environment (as OpenAI's gym)
			// /How can I call render???
			//env.render(); // Render the environment (as OpenAI's gym)
			//total_reward += reward
		}
	}
	return 1;
}

But I really do not know how to get action from Gym and to render it in c++.
Could you pls help me? Thanks