python - Numpy.dtype has the wrong size, try recompiling

Question

When importing pandas I would get the following error:

Numpy.dtype has the wrong size, try recompiling

I am running Python 2.7.5, with Pandas 0.14.1, and Numpy 1.9.0. I have tried installing older versions of both using pip, with major errors every time. I am a beginner when it comes to Python so any help here would be much appreciated. :)

EDIT: running OS X 10.9.4

EDIT 2: here is a link to a video of me uninstalling and reinstalling Numpy + Pandas, and then running a .py file: https://www.dropbox.com/s/sx9l288jijokrar/numpy%20issue.mov?dl=0

Answer 1

I've seen this error before and it typically does have to do with pandas referencing an old version of numpy. But reinstalling may not help if your python path is still pointing to an old version of numpy.

When you install numpy via pip, pip will tell you where it was installed. Something like

pip install numpy==1.9.2
Requirement already satisfied (use --upgrade to upgrade): numpy==1.9.2 in /Library/Python/2.7/site-packages
Cleaning up...

So you have the correct version of numpy installed. But when you go into python

$ python
Python 2.7.6 (default, Sep  9 2014, 15:04:36) 
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.39)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy
>>> numpy.__file__
'/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/numpy/__init__.pyc'
>>> numpy.version.version
'1.8.0rc1'

Your path might be pointing at a different numpy.

Easiest solution I've found for this is simply to remove the unwanted version of numpy (moving it to a _bak folder for safety)

mv /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/numpy /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/numpy_bak

And now when I start python

$ python
Python 2.7.6 (default, Sep  9 2014, 15:04:36) 
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.39)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy
>>> numpy.__file__
'/Library/Python/2.7/site-packages/numpy/__init__.pyc'
>>> numpy.version.version
'1.9.2'

I've got the version I want.

For more complex workflows where different applications might need different versions of various packages, virtualenvs are a great way to go http://docs.python-guide.org/en/latest/dev/virtualenvs/. But I think for your case where you just want pandas and numpy to play nice, this approach should work fine.