Python for Unity Settings

You can find preferences for Python for Unity in the Project Settings under the Edit menu.

Python for Unity Settings

The top of the window is useful information when looking for help to explain exactly which version of the various components you are using.

Component Versions

Python for Unity bundles with it a copy of the CPython implementation for Python along with a custom build of Python for .NET. For information purposes the Settings panel verifies which version of each is in fact installed. They cannot be changed.

Site Packages

You can add site-packages that will be added to the sys.path to find additional Python modules. Changes are only applied after you restart Unity.

Python for Unity Site Packages Settings

Pip Packages

You can install Python packages using pip for your project. They will be installed inside the Library/PythonInstall/Lib/site-packages folder of the project.

Installing packages with a requirements file

You can store your required Python packages with their versions in a requirements.txt file.

If you want to share your Unity project with someone else or you are working in a team, sharing the requirements.txt file will ensure everyone is using the same versions of the same packages. Simply opening a project with a requirements.txt file will automatically install any missing packages, and uninstall unused ones.

Place the requirements file in ProjectSettings/requirements.txt in your Unity project for the Python for Unity package to find it.

For details on creating a requirements file and its uses, please refer to the pip documentation.

Unity will only apply the requirements.txt when you open a project. If you change the requirements.txt while you have a project open (for example, if you update your project from revision control while Unity is running), the Python packages will not update. To apply the new requirements you will need to restart Unity.

Installing packages on the command-line (Windows)

Click on the Spawn shell in environment button which is available in the settings panel on Windows. A PowerShell window will open, with its PATH environment variable pointing to the Unity Python installation.

Use pip3 to manage your local packages:

PS D:\UnityProjects\Python 3> pip3 install numpy
Collecting numpy
  Downloading numpy-1.21.2-cp37-cp37m-macosx_10_9_x86_64.whl (16.9 MB)
     |████████████████████████████████| 16.9 MB 3.5 MB/s
Installing collected packages: numpy
Successfully installed numpy-1.21.2

After making changes to the Python packages, make sure to update the ProjectSettings/requirements.txt file. Otherwise your changes will be reverted next time you reopen the project. You can use this command for example:

pip3 freeze > ProjectSettings/requirements.txt

Installing packages on the command-line (macOS)

In the Project window, right-click on Assets and select Reveal in Finder. Open a macOS Terminal window and type cd. Now drag the Library folder from Finder to the Terminal window and press Enter. Next, type cd PythonInstall/bin and press Enter. Your Terminal window should look something like this:

$ cd /Users/myusername/My\ Unity\ Project/Library
$ cd PythonInstall/bin

Use ./pip3 to manage your local packages:

$ ./pip3 install numpy
Collecting numpy
  Downloading numpy-1.21.2-cp37-cp37m-macosx_10_9_x86_64.whl (16.9 MB)
     |████████████████████████████████| 16.9 MB 3.5 MB/s
Installing collected packages: numpy
Successfully installed numpy-1.21.2

After making changes to the Python packages, make sure to update the ProjectSettings/requirements.txt file. Otherwise your changes will be reverted next time you reopen the project. You can use this command for example:

./pip3 freeze > ../../../ProjectSettings/requirements.txt

Limitations

  • You cannot change the internal Python version nor use a virtual environment manager like venv or conda.
  • Paths are treated as verbatim strings. You will need to expand environment variables or (on macOS and linux) the ~ denoting the home directory.