How the C++ library can make use of the Python matplotlib package is by using the Python compiled library (Python36.lib) and referencing the Python.h header file, which I got it from the Python installation path at C:\Program Files (x86)\Python3.6.3\libs. If the file you are an invalid lib file or dll file, most probably you will see the following error.
I have to ensure that I have matplotlib installed for Python. Note that I have multiple versions of the Python installed in my PC and I need to install the matplotlib package just for Python3.6.3 because I am going to use that Python version in my C++ project. I used the following command to install the matplotlib package just for Python 3.6.3
C:\Program Files (x86)\Python3.6.3>python -m pip install matplotlib.
Basically I CD the Python installation path so that when i call the Python command it will call to the 3.6.3 version, as my default Python installation at that time was 3.7.3, which is not what i want to use in my C++ project.
Note: If you are using python.exe, that means the numpy and matplotlib packages need to be compatible with the "Release" version. If you are using python_d.exe then you need to ensure numpy and matplotlib is compatible with the "Debug" version. For debug version you can use C:\Program Files (x86)\Python3.6.3>python_d.exe -m pip install matplotlib to do correct package installation. Typical error one will get when the version is not compatible is ImportError: cannot import name 'multiarray'A good guideline for using debug version of the Python with release version of matplotlib from within Visual C++ Numpy issue
The full source code for the release can be retrieved from GitHub https://github.com/leonwooster/matplotlib
