That is exactly what I'm doing with pythonnet, but I install CPython as part of larger installation.

@rionmonster one option would be to use the nuget packages for CPython and pythonnet:

https://www.nuget.org/packages/python2/
https://www.nuget.org/packages/pythonnet_py27_dotnet/

When embedding this nuget package in .NET app, you will need to set PYTHONHOME environment variable or this property PythonEngine.PythonHome in pythonnet so that CPython can be located at runtime.

Thanks for the insights @denfromufa

I eventually elected to go another route for the time being, but I was able to play around with the use of PythonHome along with the aforementioned NuGet packages. That's certainly an option I'll consider should the need arise again.

I appreciate it.

@denfromufa @rionmonster I'm attempting to do the same thing. I installed pythonnet_py27_dotnet & python2 via nuget and then I'm setting PythonEngine.PythonHome to the location of the python2 folder. Python.Runtime is giving me an error: "Unable to load DLL 'python27': The specified module could not be found." even though the DLL is in the PythonHome folder.

If I drop the DLL in the appropriate Windows\System location everything works as expected but that's what I'm trying to avoid. Any ideas on how to get pythonnet to find the python27 DLL?

@willdrob you may need to append this python path to %path% env. var. too.

Also there is outstanding issue with explicitly picking the 64-bit binary if you have Python 64-bit:

#472 (comment)

@denfromufa you are correct, I needed to append the python path to %path%.
var path = $"{Environment.GetEnvironmentVariable("Path", EnvironmentVariableTarget.Machine)};{pythonPath}";
Environment.SetEnvironmentVariable("Path", path, EnvironmentVariableTarget.Process);
It's working now, thanks for the help!

@rionmonster @denfromufa I am also implementing a similar process for packaging python code to be used within a Windows application without requiring the user to install Python. I found a way to include the python runtime as well as dependent libraries in the project itself. It turns out if you include the PythonRuntime.dll in the project and include the dependent libraries in a Lib folder in the same directory, the python script is able to be loaded and used correctly.

I am running into an issue though being that if the PYTHONHOME environment variables are set (for some system python installation), then the pythonruntime.dll will no longer find the python files in the project. It seems to prioritize searching in the paths set by environment variables first. Then if environment variables are set, the pythonruntime.dll will no longer look in the project directory.

The problem is I want to prefer using the python dependencies in my project as opposed to the user's system install since the user may not have the necessary dependencies and versions installed.

Do you all know of a fix for this? Is it possible to change the search prioritization in the Pythonnet runtime DLL?

@ryan-rogowski just hide %PYTHONHOME% in your app before loading Python runtime.

@ryan-rogowski just hide %PYTHONHOME% in your app before loading Python runtime.

Thanks @denfromufa ! Do you mean to set PYTHONHOME to an empty string prior to loading Python runtime? or how would I go about hiding the environment variable from my app?

        //Check if python environment variable is set
        string path = Environment.GetEnvironmentVariable("PYTHONHOME", EnvironmentVariableTarget.Machine);
        if (path != null) {
            Environment.SetEnvironmentVariable("PYTHONHOME", "");
        }

@wdrobinson HI I'm new so bare with me,My code looks like this
private string path = Environment.CurrentDirectory+"\\packages\\Python35\\";
PythonEngine.PythonHome=path;
PythonEngine.Initialize();

But your's is
var path = $"{Environment.GetEnvironmentVariable("Path", EnvironmentVariableTarget.Machine)};
{pythonPath}";
Environment.SetEnvironmentVariable("Path", path, EnvironmentVariableTarget.Process);

I need explanation of how you're setting path without using
PythonEngine.PythonHome=path;
and what is %path%

Wanted to add some notes about embedding the latest version of python (3+) while using pythonnet. As mentioned previously, there is a python nuget package that contains all the python runtime. It supports current python version 3.12.1 as of today (I'm using 3.9.0 below). To utilize this package and the embedded python runtime, here are the steps I've followed:

Add PackageReference's to csproj:

  <ItemGroup>
    <PackageReference Include="pythonnet" Version="3.0.3" />
    <PackageReference Include="python" Version="3.9.0" />
  </ItemGroup>

Add an item in csproj to include the python nuget package's tools folder (which contains the python runtime) in the build output folder:

  <ItemGroup>
    <None Include="$(Pkgpython)\tools\**\*" LinkBase="python" CopyToOutputDirectory="PreserveNewest" />
  </ItemGroup>

Update PythonDLL and PythonHome accordingly:

using Python.Runtime;

var pythonDir = Path.Combine(Environment.CurrentDirectory, @"python");

// hardcoded for now, but can probably be made to a bit more dynamic if we search through the `python` output directory
Runtime.PythonDLL = Path.Combine(pythonDir, "python39.dll"); 
PythonEngine.PythonHome = pythonDir;

PythonEngine.Initialize();

I suspect when copying the files from the python nuget package's tools folder, we could probably cut out some chunks that aren't required to limit our app build size (haven't messed with this yet). Also, right now I'm hardcoding the python39.dll part, but I suspect it wouldn't be too difficult to make this a little more dynamic, so you can update the python nuget package version w/o updating the hardcoded variable, but I figured this works to demonstrate the point for now.

Credit to above posters for paving the way, as well as this SO post which shed some light on how to copy the python nuget package's contents to the build output folder.

Btw, if you want to browse the full contents of the python nuget package's directory, you can view it under this folder %UserProfile%\.nuget\packages\python on windows or presumably ~/.nuget/packages/python on Mac/Linux (untested).

Hope this helps get someone on the ground a bit quicker. Now I'm trying to figure out how to install python modules at build time to the output directory...

As for installing python modules, here's a really simple example target after build/publish that accomplishes this:

    <Target Name="InstallPyModulesAfterBuild" AfterTargets="Build">
        <PropertyGroup>
          <PyBaseDir>$(OutputPath)</PyBaseDir>
          <PyModules>cryptography pyasyncore boto3 prompt_toolkit google-auth requests</PyModules>
        </PropertyGroup>
        <Message Text="Installing python modules (PyBaseDir = `$(PyBaseDir)`): $(PyModules)" Importance="High" />
        <Exec Command="$(PyBaseDir)python\python.exe -m pip install $(PyModules) --quiet --disable-pip-version-check" />
    </Target>

    <Target Name="InstallPyModulesAfterPublish" AfterTargets="Publish">
        <PropertyGroup>
          <PyBaseDir>$(PublishDir)</PyBaseDir>
          <PyModules>cryptography pyasyncore boto3 prompt_toolkit google-auth requests</PyModules>
        </PropertyGroup>
        <Message Text="Installing python modules (PyBaseDir = `$(PyBaseDir)`): $(PyModules)" Importance="High" />
        <Exec Command="$(PyBaseDir)python\python.exe -m pip install $(PyModules) --quiet --disable-pip-version-check" />
    </Target>

Note: I'm sure there's an easy way to simplify using the same logic for both build & publish, but this worked well enough for me now, albeit it is essentially installing/downloading the python modules twice.