When trying to build a Python executable with Pyinstaller, fails to find an existing scipy module

Question

I have a build script for one of my established Python applications that uses Pyinstaller. This script has been working fine for over a year. Then today, I added to one of the source files for this application the line

import scipy.stats

because I want to use scipy.stats.linregress. This now causes the build script to crash with a long error traceback (apparently going back through a sequence of modules that import each other) ending with

  File "C:\Users\462974\Documents\Local Sandbox\fof\TRUNK\programs\CDFParsing\build\pyi.win32\CDFGUI\outPYZ1.pyz/scipy.sparse.csgraph", line 148, in <module>
  File "C:\Python27\pyinstaller-1.5\iu.py", line 436, in importHook
    mod = _self_doimport(nm, ctx, fqname)
  File "C:\Python27\pyinstaller-1.5\iu.py", line 495, in doimport
    mod = importfunc(nm)
  File "C:\Python27\pyinstaller-1.5\iu.py", line 297, in getmod
    mod = owner.getmod(nm)
  File "C:\Python27\pyinstaller-1.5\archive.py", line 468, in getmod
    return iu.DirOwner.getmod(self, self.prefix+'.'+nm)
  File "C:\Python27\pyinstaller-1.5\iu.py", line 109, in getmod
    mod = imp.load_module(nm, fp, attempt, (ext, mode, typ))
  File "_shortest_path.pyx", line 18, in init scipy.sparse.csgraph._shortest_path (scipy\sparse\csgraph\_shortest_path.c:14224)
  File "C:\Python27\pyinstaller-1.5\iu.py", line 455, in importHook
    raise ImportError, "No module named %s" % fqname
ImportError: No module named scipy.sparse.csgraph._validation

This is puzzling because the module located at C:\Python27\Lib\site-packages\scipy\sparse\csgraph_validation.py very much exists. Why did adding scipy to my build break it (importing numpy works just fine), could it be failing to find it?

Answer 1

Not entirely sure why, but including the following definition in my code after the import statement fixed it:

def fix_dependencies():
    from scipy.sparse.csgraph import _validation