pythonpathpyfftw

pyFFTW doesn't find libfftw3l.so while import

In my Raspbian system I have succesfully installed pyFFTW, but there is a problem while import package.

  import pyfftw
    File "/usr/local/lib/python3.4/dist-packages/pyfftw/__init__.py", line 16, in <module>
  from .pyfftw import ( 
ImportError: libfftw3l.so.3: cannot open shared object file: No such file or directory

Actually, I have FFTW installed from source.

I've dig into __init__.py and there is an relative import line:

from .pyfftw import (
              FFTW
              blah blah )

there is no module pyfftw in the . folder but I suppose this line indicates to ./pyfftw.cpython-34m.so file which probably wraps C code of FFTW.

How to tell to this pyfftw.cpython-34m.so file where it should look for correct path?

Solution

  • The problem was with PYTHONPATH.

    To check if the file is somewhere at the disk:

    $ sudo file / -name libfftw3l.so.3
/home/pi/bin/fftw-3.3.5/.libs/libfftw3.so.3
/usr/lib/arm-linux-gnueabihf/libfftw3.so.3
/usr/local/lib/libfftw3.so.3

    And add a line before import pyfftw (see here):

    import sys
sys.path.append('/usr/local/lib/libfftw3.so.3')