Python.NET

Python.NET

Installation

Installing NuGet Package Manager

• Download the latest NuGetForUnity .unitypackage here
• In Unity, go to Assets > Import Package > Custom Package, locate where you downloaded NuGetForUnity, and install it.
• You should now see NuGet in the Unity menu bar.

Installing Python.NET

• In Unity, go to NuGet > Manage NuGet Packages, select Show All Versions and Show Prerelease.
• Search for pythonnet.
• Install pythonnet Version 3.0.0-preview2021-05-03.

Installing Embedded Python

• Download a version of embedded python. I used latest release for winx64
• In Unity, create a new folder under Assets called StreamingAssets.
• Extract the .zip of your downloaded Python into the StreamingAssets folder.
• To enable pip, download get-pip.py and save it in the Python folder (Assets/StreamingAssets/python-3.9.5-embed-amd64)
• Run get-pip.py in command line. First cd into Assets/StreamingAssets/python-3.9.5-embed-amd64, then execute

python.exe get-pip.py

• Now you can install any module you want with

python.exe -m pip install module-name

Final Steps

• You should go to Edit > Project Settings > Player > Other Settings > Configuration and change the Api Compatibility Level to .Net 4.x to be safe. Apparently there can be some issues using .Net Standard 2.0.

Using Python.NET in Unity

Python.NET in a C# Script

• In a C# script you will want to include in the Start() method. This locates the Python.Runtime.dll

void Start()
{
    Runtime.PythonDLL = Application.dataPath + "/StreamingAssets/python-3.9.5-embed-amd64/python39.dll";
    PythonEngine.Initialize(mode: ShutdownMode.Reload);
}

• You will also want a method for shutting down Python.

public void OnApplicationQuit()
{
    if (PythonEngine.IsInitialized)
    {
        PythonEngine.Shutdown(ShutdownMode.Reload);
    }
}

• You should wrap all of your code in the Py.GIL (Python Global Interpreter Lock) which is a mutex that ensures only one thread has control of the Python interpreter at a time.

using (Py.GIL())
{

}

• One of the first things you will want to do is import sys.

dynamic sys = PyModule.Import("sys");

• Now you can add the path of Python scripts to the Path so that you can import them. In this example, I have script.py in the C:/Users/Jacob Bream/Documents/Biomojo/Unipy/Unipy7/Assets/Python directory.

sys.path.append(@"C:/Users/Jacob Bream/Documents/Biomojo/Unipy/Unipy7/Assets/Python");
dynamic scope = Py.Import("script");

• With the scope variable, you can access variables, methods, classes, etc in the Python script. You will see examples of this in CallingPython.cs

Limitations

• Currently, haven't figured out a way to get it working with Hololens.
• When shut down, pythonnet will not fully wipe memory and references. Related Issue