pythonnet 3.0.0rc5

.NET and Mono integration for Python

Python.NET is a package that gives Python programmers nearly seamless integration with the .NET Common Language Runtime (CLR) and provides a powerful application scripting tool for .NET developers. It allows Python code to interact with the CLR, and may also be used to embed Python into a .NET application.

Note

The master branch of this repository tracks the ongoing development of version 3.0. Backports of patches to 2.5 are tracked in the backports-2.5 branch.

Calling .NET code from Python

Python.NET allows CLR namespaces to be treated essentially as Python packages.

import clr
from System import String
from System.Collections import *

To load an assembly, use the AddReference function in the clr module:

import clr
clr.AddReference("System.Windows.Forms")
from System.Windows.Forms import Form

Embedding Python in .NET

• You must set Runtime.PythonDLL property or PYTHONNET_PYDLL environment variable starting with version 3.0, otherwise you will receive BadPythonDllException (internal, derived from MissingMethodException) upon calling Initialize. Typical values are python38.dll (Windows), libpython3.8.dylib (Mac), libpython3.8.so (most other Unix-like operating systems).

• Then call PythonEngine.Initialize(). If you plan to use Python objects from multiple threads, also call PythonEngine.BeginAllowThreads().

• All calls to python should be inside a using (Py.GIL()) {/* Your code here */} block.

• Import python modules using dynamic mod = Py.Import("mod"), then you can call functions as normal, eg mod.func(args).

• Use mod.func(args, Py.kw("keywordargname", keywordargvalue)) or mod.func(args, keywordargname: keywordargvalue) to apply keyword arguments.

• All python objects should be declared as dynamic type.

• Mathematical operations involving python and literal/managed types must have the python object first, eg. np.pi * 2 works, 2 * np.pi doesn’t.

Example

static void Main(string[] args)
{
    PythonEngine.Initialize();
    using (Py.GIL())
    {
        dynamic np = Py.Import("numpy");
        Console.WriteLine(np.cos(np.pi * 2));

        dynamic sin = np.sin;
        Console.WriteLine(sin(5));

        double c = (double)(np.cos(5) + sin(5));
        Console.WriteLine(c);

        dynamic a = np.array(new List<float> { 1, 2, 3 });
        Console.WriteLine(a.dtype);

        dynamic b = np.array(new List<float> { 6, 5, 4 }, dtype: np.int32);
        Console.WriteLine(b.dtype);

        Console.WriteLine(a * b);
        Console.ReadKey();
    }
}

Output:

1.0
-0.958924274663
-0.6752620892
float64
int32
[  6.  10.  12.]

Resources

Information on installation, FAQ, troubleshooting, debugging, and projects using pythonnet can be found in the Wiki:

https://github.com/pythonnet/pythonnet/wiki

Mailing list

https://mail.python.org/mailman/listinfo/pythondotnet

Chat

https://gitter.im/pythonnet/pythonnet

.NET Foundation

This project is supported by the .NET Foundation.