Search code examples
c#python-3.xscipyblaspython-cffi

ImportError: DLL load failed while importing _fblas, when running Python from Visual Studio C# via CFFI

I'm trying to run an image processing Python script from Visual Studio C# using CFFI. I have compiled the Python script feature-extraction.py into the DLL feature-extraction.dll, which I wrap into C# code via P/Invoke:

[DllImport(@"..\..\feature-extraction.dll", CallingConvention = CallingConvention.Cdecl)]
        static extern void GetFeatures(
            [MarshalAs(UnmanagedType.LPStr)] string path,
            [In, Out, MarshalAs(UnmanagedType.LPArray, ArraySubType = UnmanagedType.LPStr)] string[] featureNames, 
            [In, Out] float[] featureValues);

When calling GetFeatures(path, names, values), I get the following error: enter image description here

I reinstalled scikit-image and scipy (pip install scikit-image, pip install scipy), and also added the Pythonwin and Python's win32\lib folders to PATH, but I still have this issue. I tried pip install blas, pip install _fblas, but it says No matching distribution for blas.

How can I resolve this issue? Is there a specific blas package that I need to install, in addition to scipy? Thanks in advance!

LE: I can run feature-extraction.py successfully from anaconda3 prompt, which makes me think there is some issue with the runtime environment when running from C#

Solution

  • It worked after I reinstalled SciPy from sources using the instructions in https://scipy.github.io/devdocs/building/windows.html. Turns out, I had to first install OpenBLAS, and then Scipy.