How to make c# in Unity communicate with Python

This is what I use for communication between unity and python. A mix from different sources/tutorials.

(It works for me, but a known problem is that Unity freezes when there is an error in python. I already wrote a try/catch method that returns an empty bytearray, but that doesn't seem to work.)

C# script

using UnityEngine;
//using System.Net;
using System.Net.Sockets;
using System;

public class SocketFloat : MonoBehaviour
{
    public string ip = "127.0.0.1";
    public int port = 60000;
    private Socket client;
    [SerializeField]
    private float[] dataOut, dataIn; //debugging

    /// <summary>
    /// Helper function for sending and receiving.
    /// </summary>
    /// <param name="dataOut">Data to send</param>
    /// <returns></returns>
    protected float[] ServerRequest(float[] dataOut)
    {
        //print("request");
        this.dataOut = dataOut; //debugging
        this.dataIn = SendAndReceive(dataOut); //debugging
        return this.dataIn;
    }

    /// <summary> 
    /// Send data to port, receive data from port.
    /// </summary>
    /// <param name="dataOut">Data to send</param>
    /// <returns></returns>
    private float[] SendAndReceive(float[] dataOut)
    {
        //initialize socket
        float[] floatsReceived;
        client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        client.Connect(ip, port);
        if (!client.Connected) {
            Debug.LogError("Connection Failed");
            return null; 
        }

        //convert floats to bytes, send to port
        var byteArray = new byte[dataOut.Length * 4];
        Buffer.BlockCopy(dataOut, 0, byteArray, 0, byteArray.Length);
        client.Send(byteArray);

        //allocate and receive bytes
        byte[] bytes = new byte[4000];
        int idxUsedBytes = client.Receive(bytes);
        //print(idxUsedBytes + " new bytes received.");

        //convert bytes to floats
        floatsReceived = new float[idxUsedBytes/4];
        Buffer.BlockCopy(bytes, 0, floatsReceived, 0, idxUsedBytes);

        client.Close();
        return floatsReceived;
    }
}

Python code

import socket
import struct
import traceback
import logging
import time

def sending_and_reciveing():
    s = socket.socket()
    socket.setdefaulttimeout(None)
    print('socket created ')
    port = 60000
    s.bind(('127.0.0.1', port)) #local host
    s.listen(30) #listening for connection for 30 sec?
    print('socket listensing ... ')
    while True:
        try:
            c, addr = s.accept() #when port connected
            bytes_received = c.recv(4000) #received bytes
            array_received = np.frombuffer(bytes_received, dtype=np.float32) #converting into float array

            nn_output = return_prediction(array_received) #NN prediction (e.g. model.predict())

            bytes_to_send = struct.pack('%sf' % len(nn_output), *nn_output) #converting float to byte
            c.sendall(bytes_to_send) #sending back
            c.close()
        except Exception as e:
            logging.error(traceback.format_exc())
            print("error")
            c.sendall(bytearray([]))
            c.close()
            break

sending_and_reciveing() 

If you want to make a request, let your Unity script (the one you are working with) derive from SocketFloat:

public class Turing : SocketFloat

Calling ServerRequest returns a predictions from Python.

float[] prediction = ServerRequest(myArray)