FANN Python Bindings Failing

Question

I just built and installed libfann and the associated python bindings. The python setup seemed to run ok:

$ sudo python setup.py install
Running SWIG before: swig -c++ -python pyfann/pyfann.i
running install
running build
running build_py
copying pyfann/libfann.py -> build/lib.macosx-10.5-x86_64-2.7/pyfann
running build_ext
building 'pyfann._libfann' extension
gcc -fno-strict-aliasing -I/Users/dwilliams/Desktop/Anaconda/include -arch x86_64 -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -DSWIG_COMPILE -I../src/include -I/Users/dwilliams/Desktop/Anaconda/include/python2.7 -c pyfann/pyfann_wrap.cxx -o build/temp.macosx-10.5-x86_64-2.7/pyfann/pyfann_wrap.o
cc1plus: warning: command line option "-Wstrict-prototypes" is valid for Ada/C/ObjC but not for C++
g++ -bundle -undefined dynamic_lookup -L/Users/dwilliams/Desktop/Anaconda/lib -arch x86_64 -arch x86_64 build/temp.macosx-10.5-x86_64-2.7/pyfann/pyfann_wrap.o ../src/doublefann.o -o     build/lib.macosx-10.5-x86_64-2.7/pyfann/_libfann.so
running install_lib
creating /Users/dwilliams/Desktop/Anaconda/lib/python2.7/site-packages/pyfann
copying build/lib.macosx-10.5-x86_64-2.7/pyfann/__init__.py ->     /Users/dwilliams/Desktop/Anaconda/lib/python2.7/site-packages/pyfann
copying build/lib.macosx-10.5-x86_64-2.7/pyfann/_libfann.so -> /Users/dwilliams/Desktop/Anaconda/lib/python2.7/site-packages/pyfann
copying build/lib.macosx-10.5-x86_64-2.7/pyfann/libfann.py -> /Users/dwilliams/Desktop/Anaconda/lib/python2.7/site-packages/pyfann

But then import fails:

$ python -c 'import pyfann'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "pyfann/__init__.py", line 4, in <module>
    import libfann
  File "pyfann/libfann.py", line 26, in <module>
    _libfann = swig_import_helper()
  File "pyfann/libfann.py", line 18, in swig_import_helper
    import _libfann
ImportError: No module named _libfann

Anyone know how to solve this?

Answer 1

I had a similar problem, but using python 3 on Mac OS 10.7. The following worked for me so hopefully it might help you out a bit:

My error, similar to yours:

>>> import pyfann
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/site-packages/pyfann/__init__.py", line 4, in <module>
    import libfann
ImportError: No module named 'libfann'

So, I have a look around inside the file __init__.py, it looks like this:

#
# Fast Artificial Neural Network library for Python
#
import libfann
__all__ = [
    'libfann'
]

For some reason it cannot find libfann, but libfann is in the exact same folder as __init__.py. Maybe we can edit __init__.py and tell it where libfann is:

#
# Fast Artificial Neural Network library for Python
#

# import imp so we can load modules ourselves rather than through import magic
import imp

# try to load libfann, giving the exact path of where libfann resides
imp.load_source ('libfann','/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/site-packages/pyfann/libfann.py')

Then try and run one of the examples:

python3 ~/Downloads/FANN-2.2.0-Source/python/examples/simple_train.py 
FANN Error 1: Unable to open configuration file "../../examples/xor.data" for reading.
FANN Error 2: Unable to open configuration file "nets/xor_float.net" for writing.

I had to open simple_train.py and enter the full paths where it complains that it can't find the configuration files, but now it runs ok:

python3 ~/Downloads/FANN-2.2.0-Source/python/examples/simple_train.py
Max epochs   100000. Desired error: 0.0001000000.
Epochs            1. Current error: 0.2500073016. Bit fail 4.
Epochs           39. Current error: 0.0000279390. Bit fail 0.

Answer 2

In my case "import fann2.libfann as libfann" worked.

Thomas