How do I run a Python script from C#?

Question

This sort of question has been asked before in varying degrees, but I feel it has not been answered in a concise way and so I ask it again.

I want to run a script in

Answer 1

Execute Python script from C

Create a C# project and write the following code.

using System;
using System.Diagnostics;
using System.IO;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            run_cmd();
        }

        private void run_cmd()
        {

            string fileName = @"C:\sample_script.py";

            Process p = new Process();
            p.StartInfo = new ProcessStartInfo(@"C:\Python27\python.exe", fileName)
            {
                RedirectStandardOutput = true,
                UseShellExecute = false,
                CreateNoWindow = true
            };
            p.Start();

            string output = p.StandardOutput.ReadToEnd();
            p.WaitForExit();

            Console.WriteLine(output);

            Console.ReadLine();

        }
    }
}

Python sample_script

print "Python C# Test"

You will see the 'Python C# Test' in the console of C#.

Answer 2

If you're willing to use IronPython, you can execute scripts directly in C#:

using IronPython.Hosting;
using Microsoft.Scripting.Hosting;

private static void doPython()
{
    ScriptEngine engine = Python.CreateEngine();
    engine.ExecuteFile(@"test.py");
}

Get IronPython here.

Answer 3

I ran into the same problem and Master Morality's answer didn't do it for me. The following, which is based on the previous answer, worked:

private void run_cmd(string cmd, string args)
{
 ProcessStartInfo start = new ProcessStartInfo();
 start.FileName = cmd;//cmd is full path to python.exe
 start.Arguments = args;//args is path to .py file and any cmd line args
 start.UseShellExecute = false;
 start.RedirectStandardOutput = true;
 using(Process process = Process.Start(start))
 {
     using(StreamReader reader = process.StandardOutput)
     {
         string result = reader.ReadToEnd();
         Console.Write(result);
     }
 }
}

As an example, cmd would be @C:/Python26/python.exe and args would be C://Python26//test.py 100 if you wanted to execute test.py with cmd line argument 100. Note that the path the .py file does not have the @ symbol.

Answer 4

I am having problems with stdin/stout - when payload size exceeds several kilobytes it hangs. I need to call Python functions not only with some short arguments, but with a custom payload that could be big.

A while ago, I wrote a virtual actor library that allows to distribute task on different machines via Redis. To call Python code, I added functionality to listen for messages from Python, process them and return results back to .NET. Here is a brief description of how it works.

It works on a single machine as well, but requires a Redis instance. Redis adds some reliability guarantees - payload is stored until a worked acknowledges completion. If a worked dies, the payload is returned to a job queue and then is reprocessed by another worker.

Answer 5

Just also to draw your attention to this:

https://code.msdn.microsoft.com/windowsdesktop/C-and-Python-interprocess-171378ee

It works great.

Answer 6

Set WorkingDirectory or specify the full path of the python script in the Argument

ProcessStartInfo start = new ProcessStartInfo();
start.FileName = "C:\\Python27\\python.exe";
//start.WorkingDirectory = @"D:\script";
start.Arguments = string.Format("D:\\script\\test.py -a {0} -b {1} ", "some param", "some other param");
start.UseShellExecute = false;
start.RedirectStandardOutput = true;
using (Process process = Process.Start(start))
{
    using (StreamReader reader = process.StandardOutput)
    {
        string result = reader.ReadToEnd();
        Console.Write(result);
    }
}