How to install numpy and scipy on OSX?

Sounds as though you might be trying to use a 32-bit library from a 64-bit Python. Looks like there's an unofficial 64-bit Numpy available for Snow Leopard.

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EDIT: The Python 2.6 .dmg available here is indeed 32-bit. (Specifically, it's a universal binary containing both i386 and ppc versions). The same is true of the regular numpy and scipy .dmg releases available here. (How do I know? See below!) So if you use those releases together you should be fine.

But you're not fine - so my guess is you're not using the version of Python from the 2.6 .dmg you downloaded. If you're running an executable python script, e.g.:

$ ./my-script.py

then you could try specifying the Python you're using explicitly on the command line. Looks like the MacPython .dmg installs to /usr/local/bin/python, so try:

$ /usr/local/bin/python2.6 myscript.py

Any joy?

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How I determined the architecture the contents of those .dmg files are built for...

1. Mount the .dmg (i.e. double-click it to open a volume)

2. Use gunzip and pax to unpack the package contents to a local directory, e.g.:

   $ mkdir tmp
   $ cd tmp
   $ gunzip -c /Volumes/Universal\ MacPython\ 2.6/MacPython.mpkg/Contents/Packages/PythonUnixTools-2.6.pkg/Contents/Archive.pax.gz | pax
   

3. Use file to examine binary files in the package contents

   $ file Versions/2.6/bin/python
   Versions/2.6/bin/python: Mach-O universal binary with 2 architectures
   Versions/2.6/bin/python (for architecture ppc): Mach-O executable ppc
   Versions/2.6/bin/python (for architecture i386):    Mach-O executable i386
   

I had the same error message when I was trying my freshly-installed numpy and scipy in python2.7 on Mac OSX 10.6.8 . Later I found out that there were two .dmg for python2.7:

• numpy-1.6.2-py2.7-python.org-macosx10.3.dmg
• numpy-1.6.2-py2.7-python.org-macosx10.6.dmg

It was the package in 10.3.dmg giving me the error message about multiarray.so. After installing the one in 10.6.dmg, I got rid of this error message.

I had problems with numpy until I installed in a virtualenv, now I don't have any issues. I would definitely suggest trying that.