How do to use a python script in Unity?

Unity not supported python, But you Can write Python Code and run it by Socket programing, Create Server with python and send data,in C# Connect to server and use data sended with python.

I don’t know how recent it is but there is a Unity package for python available on unity 2019.3 and further versions.

Warning the first versions of this package can’t use Python3.

You can see more for yourself by the following link.
https://docs.unity3d.com/Packages/[email protected]/manual/index.html

I hope this may help you.

I try to use python once on Unity and I found a few ways:

1. There is a package call "IronPython" where you can add a python file to your unity project and then call a function from C# to your python code, to do that you should follow this:

We already know that we can use python to use .net internal calls.
Now we may use the same to start a console that can accept a scripting language in Unity engine.
To do this we have to include certain dll files.
These dll files must be present in Assets>plugins

IronPython.dll
IronPython.Modules.dll
Microsoft.Scripting.Core.dll
Microsoft.Scripting.dll
Microsoft.Scripting.Debugging.dll
Microsoft.Scripting.ExtensionAttribute.dll
Microsoft.Dynamic.dll

Once the Plugins are in place.

Initiate the Cs code

PythonEngine engine = new PythonEngine(); 
engine.LoadAssembly(Assembly.GetAssembly(typeof(GameObject))); 
engine.ExecuteFile("Test.py");

Where test.py is the python code.

Initiate python side:

import UnityEngine from UnityEngine 
import * 
Debug.Log("Hello world from IronPython!")

References:
https://github.com/cesardeazevedo/Unity3D-Python-Editor
http://techartsurvival.blogspot.in/2013/12/embedding-ironpython-in-unity-tech-art.html
IronPython in Unity3D

the issue with this way is that most of the python module are not supported.

2.the second way is to create a file like json that contain the data you want to send to the json and then create an output json that send the output from the python script, this way is very limited with what you can send because the data must be contain in your json.

3. the last way that work for me is to install the Nuget package and copy the script from python to c# line by line with the relevent module installed in Unity and it’s work for me, but copy a long code can take time.
   this is a reference to the package:
   https://github.com/GlitchEnzo/NuGetForUnity
   and then to install the relevent package you should press on NuGet → Manage NuGet Packages and the choose the relevent package(for me it was Numpy and it work grate).

hope it will help you

We are thrilled to announce that Python for Unity 4.0.0-exp.5 is now available!

4.0.0-exp.5 is a major upgrade from our last public release, and incorporates a large number of changes. In summary:
Based on Python 3.7; scripts based on Python 2.7 will need to be ported.
Users no longer need to install Python on their system.
In-process Python is no longer reinitialized when the Unity domain reloads.
Removed the out-of-process API. The PySide example now runs in-process and is much simpler.
Limited support for a virtual environment workflow via the ProjectSettings/requirements.txt file.
Many bug fixes.
Documentation for the Python for Unity package is available here, and the full changelog can be found here.

This is an experimental release, and thus is not visible in Package Manager. To install this package, open Package Manager, click the + at the top left and select Add package by name…. Enter com.unity.scripting.python as the name and and 4.0.0-exp.5 as the version and click Add. Alternatively, you may edit Packages/manifest.json and add "com.unity.scripting.python": "4.0.0-exp.5", to the list of dependencies, or edit the existing entry for Python for Unity to update the version.

Soursce: https://forum.unity.com/threads/python-for-unity-release-announcements.1084688/

Documentation: https://docs.unity3d.com/Packages/[email protected]/manual/index.html