Develop Reference

C# - Python interop using Python.Net [No module named '_ctypes']

I am trying to use Python.NET to perform interop between C# and Python on a Windows machine.
Specifically I have the following code.
PythonEngine.PythonHome = #"C:\Python\3_5_4";
PythonEngine.PythonPath = #"C:\Python\3_5_4\Lib;C:\Python\3_5_4\Lib\site-packages";
using (Python.Runtime.Py.GIL())
{
dynamic np = Py.Import("numpy");
dynamic sin = np.sin;
Console.WriteLine(sin);
}
While I can successfully execute a general python statement as such:
var res = PythonEngine.Eval("1 + 1");
Console.WriteLine(res);
//res = 2
Which indicates that the python engine itself is working successfully, I can also invoke something like this:
var html = Py.Import("html");
Console.WriteLine(html);
//html = <module 'html' from 'C:\\Python\\3_5_4\\Lib\\html\\__init__.py'>
Which further indicates that the module loading functionality is also working correctly.
However whenever I attempt to invoke the line:
dynamic np = Py.Import("numpy");
I receive the following error:
{"ImportError : No module named '_ctypes'"}.
[' File "C:\\Python\\3_5_4\\Lib\\site-packages\\numpy\\__init__.py", line 140, in <module>\n from . import _distributor_init\n', ' File "C:\\Python\\3_5_4\\Lib\\site-packages\\numpy\\_distributor_init.py", line 9, in <module>\n from ctypes import WinDLL\n', ' File "C:\\Python\\3_5_4\\Lib\\ctypes\\__init__.py", line 8, in <module>\n from _ctypes import Union, Structure, Array\n']
The file referenced is located # 'C:\Python\3_5_4\Lib\ctypes\__init__.py'.
I have verified that all the expected paths are set correctly and that the Ctypes folder exists in my python path.
I have tried everything from uninstalling and reinstalling Python to modifying the ctypes/__init__.py file to try and import Ctypes directly to no effect.
Having researched this topic online throughly I have found a number of suggestions which point to running yum install libffi-devel as detailed here. However this does not appear to be something that I can perform on windows given that yum appears to be a Linux only application.
Can anyone provide any guidance?

How do I run an external python script that's importing 3rd party library himself, in C#?

I was trying to combine a Python code with C#, to use all those cool libraries like Speech Recognition inside my C# application.
I made two different projects one for python (IronPython) where I've included the module I need (Speech Recognition) through the python environment in VS2017 and the other one is just a console application where I want to call this app.
I thought the point was to change the searchPaths of Ironpython and afterwards it'll work.
Maybe I'm doing something wrong or maybe it just shouldn't work anyway?
C# Code Main.cs:
using IronPython.Hosting;
using System.Collections.Generic;
private static void Main(string[] args)
{
//Using Iron python
var engine = IronPython.Hosting.Python.CreateEngine();
System.Console.WriteLine("Search paths:");
ICollection<string> searchPaths = engine.GetSearchPaths();
foreach (string path in searchPaths)
{
System.Console.WriteLine(path);
}
System.Console.WriteLine();
searchPaths.Add("..\\..");
///Trying to add a searchPath for the place with the module I need
searchPaths.Add(#"C:\Program Files (x86)\Microsoft Visual
Studio\Shared\Anaconda3_64\Lib\site-packages");
engine.SetSearchPaths(searchPaths);
var res = engine.CreateScriptSourceFromFile(
#"D:\Python\Projects\TestSpeechRecognition
\TestForNETinPython\TestForNETinPython.py"
);
engine.ImportModule("speech_recognition");
var result = res.Execute();
}
Python code
import speech_recognition as sr
r = sr.Recognizer()
with sr.Microphone() as source:
print ("Hello: ")
audio = r.listen(source)
try:
print ("I said: " + r.recognize_google(audio))
except sr.UnknownValueError:
print ("Cant't rec")
except sr.RequestError as e:
print ("Can't connect: (0)".format(e))
Exception:
Unhandled Exception:
IronPython.Runtime.Exceptions.ImportException: no module named speech_recognition
at IronPython.Hosting.PythonService.ImportModule(ScriptEngine engine, String name)
at IronPython.Hosting.Python.ImportModule(ScriptEngine engine, String moduleName)
at Test.Program.Main(String[] args) in D:\Python\Projects\TestSpeechRecognition\Test\Program.cs:line 26
I even read some literature about creating the modules like this one http://www.needfulsoftware.com/IronPython/IronPythonCS2 or this one it's for pythonnet and a little bit creepy, but I guess it may be useful (NoteBook).
Hope someone can use it to solve the problem.

What is the equivalent of GetEncoding("28591") of C# in Python?

I want to get the code of a device from COM6, I easily get the output from C# using the code below:
serialPort1.Encoding = System.Text.Encoding.GetEncoding(28591);
but I don't know how to do it in Python.
I already tried:
import serial
import time
ser = serial.Serial()
ser.port='COM6'
ser.baudrate=9600
ser.parity=serial.PARITY_NONE
ser.stopbits=serial.STOPBITS_ONE
ser.bytesize=serial.EIGHTBITS
ser.timeout=2
if ser.is_open:
ser.close()
else:
ser.open()
print("connected to: " + ser.portstr)
while True:
ser.flushInput()
time.sleep(0.01)
data_raw = (ser.readline())
print(data_raw.decode("utf-8"))

You can use pythonnet to access .Net libraries. When I run the below code I get System.Text.Latin1Encoding
import clr
from System import Text
result = Text.Encoding.GetEncoding(28591)
print(result)
More here - https://github.com/pythonnet/pythonnet

Executing python script with zmq from C# using IronPython not working

I'm using ZeroMQ for inter-process communication between C# managed application and python script. When calling script from C#, using IronPython I get following error :
An unhandled exception of type
IronPython.Runtime.Exceptions.ImportException occurred in
Microsoft.Dynamic.dll
Additional information: cannot import constants from
zmq.backend.cython
Python code (test.py file):
import sys, zmq, time
def execute(input):
context = zmq.Context()
publisher = context.socket(zmq.PUB)
publisher.bind("tcp://*:18800")
time.sleep(1)
publisher.send(input) #just echo input parameter
And this is how I execute .py code from my C# app :
static void Main(string[] args)
{
var options = new Dictionary<string, object>();
options["Frames"] = true;
options["FullFrames"] = true;
ScriptEngine _engine = Python.CreateEngine(options);
ScriptRuntime _runtime = _engine.Runtime;
ICollection<string> _searchPaths = _engine.GetSearchPaths();
_searchPaths.Add(#"C:\Python27\");
_searchPaths.Add(#"C:\Python27\Lib\");
_searchPaths.Add(#"C:\Python27\Scripts\");
_searchPaths.Add(#"C:\Python27\libs\");
_searchPaths.Add(#"C:\Python27\DLLs\");
_searchPaths.Add(#"C:\Python27\include\");
_searchPaths.Add(#"C:\Python27\lib\site-packages");
_engine.SetSearchPaths(_searchPaths);
dynamic wrapperObj = _runtime.UseFile("test.py");
wrapperObj.execute("test");
}
Note that some code is omitted for brevity, and not actually relevant for this scenario. When manually invoking .py script through the command line, everything works fine, I'm able to pass data around and my C# app is receiving messages.
Anyone knows what is this error and how can be solved?
EDIT : While I was desperate and almost gave up, I tried to write quick named-pipes support, and guess what - similar error:
An unhandled exception of type IronPython.Runtime.Exceptions.ImportException occurred in
Microsoft.Dynamic.dll
Additional information: No module named win32file
This time, my test.py looks like this:
import win32file
def execute(input):
handle = win32file.CreateFile(r"\\.\pipe\test_pipe",
win32file.GENERIC_WRITE,
0, None,
win32file.OPEN_EXISTING,
0, None)
if handle:
win32file.WriteFile(self.handle, input, None)
win32file.FlushFileBuffers(self.handle)
win32file.SetFilePointer(self.handle, 0, win32file.FILE_BEGIN)
I'm not really sure if I have more options for this kind of interoperability, but I'm starting to think that IronPython can just cover basic usage scenarios (when calling pure python code from C#), not to mention matplotlib, numpy or astropy that I will certanly need later on.
Thanks in advance!
Regards,
Civa

Embedding IronPython and overwriting Environment Variables

I embed an IronPython interpreter in a C# application to execute a Python script. The script evaluates a specific environment variable VAR1 using os.environ['VAR1']
I need to change the value of VAR1 temporarily before the script is executed. To do this I call
Environment.SetEnvironmentVariable("VAR1", "NEW_VALUE");
in the C# code. Unfortunately this does not work. The Python script still "sees" the old value of VAR1 (the value it had when the hosting C# application started).
Here is a complete example code:
Environment.SetEnvironmentVariable("VAR1", "NEW_VALUE");
var engine = Python.CreateEngine();
engine.SetSearchPaths(new string[] { #"c:\Program Files (x86)\IronPython 2.7\Lib\" });
var ms = new MemoryStream();
engine.Runtime.IO.SetOutput(ms, Encoding.Unicode);
var script = engine.CreateScriptSourceFromString("import os\nprint os.environ['VAR1']");
script.Execute();
System.Windows.Forms.MessageBox.Show(Encoding.Unicode.GetString(ms.ToArray()));
My understanding is that the IronPython engine runs in the same process as the C# host application. If this is correct, how can the Python code and the C# code see different environment variables?
Is there a better (working) way to set an environment variable for the Python script?

Well, I still don't know why the above code doesn't work but one can simply set an environment variable in the Python environment by executing Python code that sets the variable BEFORE executing the real code:
engine.CreateScriptSourceFromString("import os\nos.environ['VAR1'] = 'NEW_VALUE'").Execute();
var CodeIReallyWantToRun = engine.CreateScriptSourceFromFile(...);
CodeIReallyWantToRun.Execute();