PythonKit

Swift framework to interact with Python.

Requirements

PythonKit requires Swift 5 or higher and has been tested on macOS, Linux and Windows.

Usage

Some Python code like this:

import sys

print(f"Python {sys.version_info.major}.{sys.version_info.minor}")
print(f"Python Version: {sys.version}")
print(f"Python Encoding: {sys.getdefaultencoding().upper()}")

Can be implemented in Swift through PythonKit with the following code:

import PythonKit

let sys = try Python.import("sys")

print("Python \(sys.version_info.major).\(sys.version_info.minor)")
print("Python Version: \(sys.version)")
print("Python Encoding: \(sys.getdefaultencoding().upper())")

Swift Package Manager

Add the following dependency to your Package.swift manifest:

.package(url: "https://github.com/pvieito/PythonKit.git", .branch("master")),

Build & Run

PythonKit can be built with Swift PM:

$ cd PythonKit
$ swift run
[*] Python 3.7
[ ] Version: 3.7.0

The Python library will be loaded at runtime, PythonKit will try to find the most modern Python version available in the system. You can force a given version with the PYTHON_VERSION environment variable or an specific Python library path or name with PYTHON_LIBRARY.

$ PYTHON_VERSION=3 swift run
[*] Python 3.5
[ ] Version: 3.5.2
$ PYTHON_VERSION=2.7 swift run
[*] Python 2.7
[ ] Version: 2.7.10
$ PYTHON_LIBRARY=libpython3.5.so swift run
[*] Python 3.5
[ ] Version: 3.5.2
$ PYTHON_LIBRARY=/usr/lib/x86_64-linux-gnu/libpython2.7.so swift run
[*] Python 2.7
[ ] Version: 2.7.10

If PythonKit cannot find and load the Python library you can set the PYTHON_LOADER_LOGGING environment variable to know from which locations PythonKit is trying to load the library:

$ PYTHON_LOADER_LOGGING=TRUE PYTHON_VERSION=3.8 PythonTool
Loading symbol 'Py_Initialize' from the Python library...
Trying to load library at 'Python.framework/Versions/3.8/Python'...
Trying to load library at '/usr/local/Frameworks/Python.framework/Versions/3.8/Python'...
Fatal error: Python library not found. Set the PYTHON_LIBRARY environment variable with the path to a Python library.

Notes

• Originally PythonKit was based on the Python module from the Swift for TensorFlow project. The mantainers of both projects have been developing them jointly and currently PythonKit is distributed as part of the Swift for TensorFlow toolchains.
• If you have questions about PythonKit you can ask on the Swift for TensorFlow Google Group or on the Swift Forums.