Python weave blitz DLL error

Question

I'm trying to use weave.blitz to speed up some code and I keep getting the following DLL error. If I run a simple code, e.g.

from scipy import * # or from NumPy import *
a = ones((512,512),'Float64')
b = ones((512,512),'Float64')

# now average
a[1:-1,1:-1] = (b[1:-1,1:-1] + b[2:,1:-1] + b[:-2,1:-1] \
+ b[1:-1,2:] + b[1:-1,:-2]) / 5.

from scipy import weave
expr = "a[1:-1,1:-1] = (b[1:-1,1:-1] + b[2:,1:-1] + b[:-2,1:-1]" \
    "+ b[1:-1,2:] + b[1:-1,:-2]) / 5."
weave.blitz(expr)

I get the following error:

Traceback (most recent call last):
  File "C:\Users\Thijs\wtest.py", line 19, in <module>
    weave.blitz(expr)
  File "C:\Python27\lib\site-packages\scipy\weave\blitz_tools.py", line 65, in blitz
    **kw)
  File "C:\Python27\lib\site-packages\scipy\weave\inline_tools.py", line 488, in compile_function
exec 'import ' + module_name
  File "<string>", line 1, in <module>
ImportError: DLL load failed: Invalid access to memory location.

I'm using the latest Pythonxy and I usually write my code in Spyder; not sure if that has anything to do with it. Any ideas?

Answer 1

I'm also using python 2.7 64bit/weave.inline under windows 7 and just met the same issue as you described here. I searched the whole internet but this post seems like the only related one and i got no answer.

I traced the weave.inline function and try to load the pyd from compiled binary. Then i found that the loading is successful if i try

python -c "import sys; sys.path.insert(0, 'C:\\Users\\zliu\\AppData\\Local\\Temp\\zliu\\python27_compiled'); import sc_d4c0ee9cff8db6a9b5fc8352299944210;" where the module name being some hash value apparently.

However if I start python interactive then input the exact same statements in the interactive mode, it just shows

ImportError: DLL load failed: Invalid access to memory location.

So next i tried to compare the output of python -c -v "..." and python -v, finally i was able to locate the devil different line:

import string

I have no idea why python -c and python interactive are different in this or why without this module the import show such an ambiguous message. But putting it at the beginning of the script just works for me.