Need to validate Python runtime library

Question

The first line of code is underlined in red, stating that the Python runtime is not installed correctly.

Although I downloaded the libraires and utility tools, it still does not detect its inclusion of the Python libraries while coding in C#.

Here is the code snippet below:

I need someone or Microsoft Copilot to provide me some steps for it to work, so that it can compile without any errors.

using Python.Runtime;  // code will not compile because Python runtime library is not included
using System;			// in Visual Studio IDE for C#.
class Program
{
    static void Main()
    {
        Runtime.PythonDLL = @"C:\Path\To\python312.dll";  // Adjust to your Python version
        PythonEngine.Initialize();
        using (Py.GIL())
        {
            dynamic transformers = Py.Import("transformers");
            dynamic pipeline = transformers.pipeline("text-classification");
            dynamic result = pipeline("This app is amazing!");
            Console.WriteLine(result);
        }
        PythonEngine.Shutdown();
    }
}

Answer 1

To get your C# code using Python (via Python.Runtime) working in Visual Studio, you need to set up the Python.NET environment.

1. Install Python and Locate python312.dll

Make sure you have installed Python 3.12 (matching your code) from https://www.python.org/downloads/windows/. Next, identify the exact path to python312.dll (usually found in C:\Users\<YourName>\AppData\Local\Programs\Python\Python312\)

2. Install Python.NET via NuGet

In Visual Studio:

• Right-click on your project → Manage NuGet Packages
• Search for: Python.Runtime
• Install the version that matches your Python version (e.g., Python.Runtime 3.12.x if you have Python 3.12)

Keep in mind that a version mismatch between Python.Runtime and your Python installation will cause runtime errors.

3. Manually Set the Runtime.PythonDLL Path

Before initializing the Python engine, make sure this line is correct:

Runtime.PythonDLL = @"C:\Path\To\python312.dll";

Replace it with the actual path on your machine, for example:

Runtime.PythonDLL = @"C:\Users\YourName\AppData\Local\Programs\Python\Python312\python312.dll";

4. Ensure your project is built as x64. Python and Python.NET are architecture-specific. If your Python is 64-bit, do this:

• Right-click project → Properties
• Go to Build tab → Set Platform Target to x64
• Also do this in the Configuration Manager (in the top toolbar)

5. Ensure Python can run this in a standalone script:

from transformers import pipeline
pipeline("text-classification")

If this fails in Python, run:

pip install transformers

Use this code:

using Python.Runtime;
using System;

class Program
{
    static void Main()
    {
        // Update this path!
        Runtime.PythonDLL = @"C:\Users\YourName\AppData\Local\Programs\Python\Python312\python312.dll";

        PythonEngine.Initialize();
        using (Py.GIL())
        {
            dynamic transformers = Py.Import("transformers");
            dynamic pipeline = transformers.pipeline("text-classification");
            dynamic result = pipeline("This app is amazing!");
            Console.WriteLine(result);
        }
        PythonEngine.Shutdown();
    }
}

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hth

Marcin

Answer 2

Hi John,

The issue you're experiencing is that the Python.NET library (Python.Runtime) isn't properly installed or referenced in your C# project. Here's how to resolve this step by step:

Solution Steps:

1. Install Python.NET via NuGet Package Manager:

Option A - Using Package Manager Console:

Install-Package pythonnet

Option B - Using Package Manager UI:

• Right-click your project in Solution Explorer
• Select "Manage NuGet Packages"
• Search for "pythonnet"
• Install the package by pythonnet

2. Verify Python Installation: Make sure you have Python installed and note the exact path:

python --version
where python

3. Update Your Code with Correct Path:

using Python.Runtime;
using System;
class Program
{
    static void Main()
    {
        // Set the correct path to your Python DLL
        Runtime.PythonDLL = @"C:\Users\[YourUser]\AppData\Local\Programs\Python\Python312\python312.dll";
        
        // Alternative: Let Python.NET find it automatically
        // Runtime.PythonDLL = "python312.dll"; // or just remove this line
        
        PythonEngine.Initialize();
        
        try
        {
            using (Py.GIL())
            {
                // Install transformers if needed
                dynamic sys = Py.Import("sys");
                Console.WriteLine($"Python version: {sys.version}");
                
                // Import transformers (make sure it's installed in your Python environment)
                dynamic transformers = Py.Import("transformers");
                dynamic pipeline = transformers.pipeline("text-classification");
                dynamic result = pipeline("This app is amazing!");
                Console.WriteLine(result);
            }
        }
        finally
        {
            PythonEngine.Shutdown();
        }
    }
}

4. Install Required Python Packages: In your command prompt/terminal:

pip install transformers torch

5. Common Issues & Solutions:

If you still get compilation errors:

• Clean and rebuild your solution
• Check that your project targets the correct .NET Framework/.NET version
• Verify the Python.NET package is compatible with your Python version

If Python DLL path issues persist:

// Let Python.NET auto-detect (remove the Runtime.PythonDLL line)
// Or use Environment.SetEnvironmentVariable
Environment.SetEnvironmentVariable("PYTHONNET_PYDLL", @"C:\Path\To\python312.dll");

6. Project File Verification: Your .csproj file should include:

<PackageReference Include="pythonnet" Version="3.0.3" />

Approach - Using IronPython: If you continue having issues with Python.NET, consider IronPython for simpler C#-Python integration:

// Install-Package IronPython
using IronPython.Hosting;
using Microsoft.Scripting.Hosting;

Debugging Tips:

• Check Visual Studio's Error List for specific error details
• Verify Python and pip are in your system PATH
• Try a simple Python.NET example first before using transformers

Let me know if you're still encountering issues after trying these steps, and please share any specific error messages you're seeing!

Hope this helps!

Thanks,  

Karan Shewale.

*************************************************************************  

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