PythonNet May 2018

pythonnet@python.org

8 participants
7 discussions

Passing a C# DateTime object to a Python script
by Ian Hannah 08 Jun '18

08 Jun '18

Hi, I have a simple python script: def test(datetime_or_doy): print datetime_or_doy.strftime('%m/%d/%Y') and I am using Python for .NET to try and call this method as follows: dynamic np = Py.Import(@"pvlib"); double d = np.irradiance.test(DateTime.Now); and I get the error: Python.Runtime.PythonException: 'AttributeError : 'DateTime' object has no attribute 'strftime'' Clearly I need to pass a Python datetime object from the C# code but how do I do that? Thanks Ian

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Speeding Up Pythonnet
by Jared Broad 22 May '18

22 May '18

Hi All, my first post here =) We're using Pythonnet in LEAN - an open source algorithmic trading platform. We load the python object and then we make it look like a C# interface <https://github.com/QuantConnect/Lean/blob/master/AlgorithmFactory/Loader.cs…> . Each time a method/property is called we see 75% of the time being spent in Pythonnet; and only 10-25% being actual work. The raw C# version of LEAN runs up to 20x faster than our python layer; we're looking for suggestions on how to improve the speed of the library / C#-Py interop. Thanks Jared -- Jared Broad www.quantconnect.com Phone-USA: +1 917 327 0556 *Democratizing Finance, Empowering Individuals* Facebook <http://www.facebook.com/QuantConnect> | Twitter <https://twitter.com/#!/QuantConnect> | LinkedIn <http://www.linkedin.com/company/quantconnect> | Skype: jaredbroad We're recruiting! Join us and make your mark on the future of finance <https://www.quantconnect.com/jobs>

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Need help in converting function of .net to python
by NicKz 👫 22 May '18

22 May '18

Hi All, I hope all of you are doing well in your life. I want to convert this .net function in python private static string decrypt(string enctxt) { string dectext = ""; string encryptKey = "HECT17IPWORI1702"; byte[] encArr = Convert.FromBase64String(enctxt); using (Aes aesObj = Aes.Create()) { Rfc2898DeriveBytes objRfc = new Rfc2898DeriveBytes(encryptKey, new Byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 }); aesObj.Key = objRfc.GetBytes(32); aesObj.IV = objRfc.GetBytes(16); using (MemoryStream ms = new MemoryStream()) { using (CryptoStream cs = new CryptoStream(ms, aesObj.CreateDecryptor(), CryptoStreamMode.Write)) { cs.Write(encArr, 0, encArr.Length); cs.Close(); } dectext = Encoding.Unicode.GetString(ms.ToArray()); } } return dectext; } Please guide me how to convert it into python. Regards Nick

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How to provide a variable of special type as method parameter
by Daniel Krause 14 May '18

14 May '18

Hi, I posted this question at stackoverflow some days ago: https://stackoverflow.com/questions/50254745/how-to-provide-a-variable-of-s… I want to use a DLL with the help of Python for .NET (pythonnet). The methods in this DLL require (pointer to?) variables as parameters. I could figure out how to call a method and to provide an integer variable as parameter. I could not figure out how to provide such a parameter variable if a special type is required (here: FTD2XX_NET.FTDI.FT_DEVICE_INFO_NODE[]). Here is a code summary, and the results: import clrimport sys sys.path.append("C:\\Users\\[...]\\FTD2XX_NET_v1.1.0\\") # path to dll clr.AddReference("System") clr.AddReference("FTD2XX_NET")from FTD2XX_NET import FTDIfrom System import UInt32 ftdi = FTDI() if __name__ == '__main__': # This method requires an integer as parameter, the code is working # M:FTD2XX_NET.FTDI.GetLibraryVersion(System.UInt32@) # summary: Gets the current FTD2XX.DLL driver version number. # returns: FT_STATUS value from FT_GetLibraryVersion in FTD2XX.DLL # param: name: LibraryVersion. The current library version. version_ = 0 # empty variable to provide as parameter ft_status, version = ftdi.GetLibraryVersion(version_) print('status: {}\nversion: {}'.format(ft_status, version)) # prints # status: 0 # version: 197140 # This method requires an FT_DEVICE_INFO_NODE[] as parameter, the code is not working # M:FTD2XX_NET.FTDI.GetDeviceList(FTD2XX_NET.FTDI.FT_DEVICE_INFO_NODE[]) # summary: Gets information on all of the FTDI devices available. # returns: FT_STATUS value from FT_GetDeviceInfoDetail in FTD2XX.DLL # param: name: devicelist. # An array of type FT_DEVICE_INFO_NODE to contain the device information # for all available devices. # no idea how to create the fitting parameter FT_DEVICE_INFO_NODE[] devicelist_ = ftdi.FT_DEVICE_INFO_NODE() # empty variable to provide as parameter print(devicelist_.Flags, devicelist_.Type, devicelist_.ID, devicelist_.LocId, devicelist_.SerialNumber, devicelist_.Description, devicelist_.ftHandle) # prints # 0 0 0 0 None None 0 status, devicelist = FTDI.GetDeviceList(devicelist_) print(devicelist) # throws a TypeError: No method matches given arguments Here <https://gist.github.com/Bovaz/aad3609abb70f23a208a> I found some c#-code where FT_DEVICE_INFO_NODE[] and GetDeviceList are used in a method: private int countDevices(){ FTDI.FT_STATUS ftStatus = FTDI.FT_STATUS.FT_OK; ftStatus = myDevice.GetNumberOfDevices(ref ftdiDeviceCount); if (ftStatus != FTDI.FT_STATUS.FT_OK) return 0; if (ftdiDeviceCount > 0) { //allocate device info list ftdiDeviceList = new FTDI.FT_DEVICE_INFO_NODE[ftdiDeviceCount]; //populate list ftStatus = myDevice.GetDeviceList(ftdiDeviceList); if (ftStatus == FTDI.FT_STATUS.FT_OK) { return (int)ftdiDeviceCount; } else return 0; } else return 0;} So my main problem seems to be the transition of ftdiDeviceList = new FTDI.FT_DEVICE_INFO_NODE[ftdiDeviceCount]; to valid python for .NET - code. It would be great if someone could provide some hints. Thanks Daniel

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mono_os_mutex_destroy issue with Python.NET
by techi eth 07 May '18

07 May '18

Hi, I am getting below error when running C# programme with mono on Linux. Please suggest hint for solution. *Mono version : 5.8.1.0* *Pyhton.NET : 2.3.0* mono_os_mutex_destroy: pthread_mutex_destroy failed with "Device or resource busy" (16) Aborted Note : I am able to run only C# programme without issue but issue comes once i run nPython.exe coming with Python.NET.

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Error in calling Python class method from C#
by techi eth 02 May '18

02 May '18

Hi, I am facing issue while calling python class function in C# programme. Can anyone give me hint what is wrong in below programme.While running I am getting error in invoking Initialize() function of class. Python module <Class.py> : def test(): print "Test called" return 1 class ClassTest: def __init__(self) def Initialize (): print " Initialize called" return 1 @staticmethod def Execute(): print "Execute called" return 1 C# Console Programme code snapshot : PythonEngine.Initialize(); using (Py.GIL()) { PyObject testClassModule = PythonEngine.ImportModule("Class"); //Calling module method PyObject result = testClassModule.InvokeMethod("test"); Console.WriteLine("Test method result = {0}", result.ToString()); PyObject classTest = testClassModule.GetAttr("ClassTest"); *classTest.InvokeMethod("Initialize "); -----------------------------> Error* classTest.InvokeMethod("Execute"); } PythonEngine.Shutdown();

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Using multiple versions of the same DLL
by Joe 01 May '18

01 May '18

Hello, I found a rather old thread (2003) that describes how multiple versions of a DLL can be used. It states > Things get a lot more complicated if you need to load more than one > version of a particular assembly (or more likely, you have a dependency > on some library the does so). In this case, the names you access via > the CLR modules will always come from the first version of the > assembly loaded (which will always win in the internals of the > runtime). (https://mail.python.org/pipermail/pythondotnet/2003-October/000010.html) Is this still correct or are there more convenient methods to do this? Kind regards, Joe

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PythonNet May 2018