title: Import sklearn fails - conflict with numpy version?
body: <p>I'm trying to import sklearn module in the interactive python environment, but I get this error message:</p>
  
  <pre><code>Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "/Library/Python/2.7/site-packages/sklearn/__init__.py", line 57, in &lt;module&gt;
      from .base import clone
    File "/Library/Python/2.7/site-packages/sklearn/base.py", line 11, in &lt;module&gt;
  from .utils.fixes import signature
    File "/Library/Python/2.7/site-packages/sklearn/utils/__init__.py", line 10, in &lt;module&gt;
  from .murmurhash import murmurhash3_32
    File "numpy.pxd", line 155, in init sklearn.utils.murmurhash (sklearn/utils/murmurhash.c:5029)
  ValueError: numpy.dtype has the wrong size, try recompiling
  </code></pre>
  
  <p>I read somewhere that this might be a problem derived by the fact that scikit-learn is compiled against an older version of numpy, but I tried to uninstall and reinstall both numpy and scikit-learn (and scipy to be sure) and the problem persists.</p>
  
  <p>These are my python modules:</p>
  
  <pre><code>giacomopoli$ pip freeze
  Warning: cannot find svn location for setuptools===0.6c12dev-r88846
  altgraph==0.10.1
  appnope==0.1.0
  attrs==15.2.0
  backports-abc==0.4
  backports.ssl-match-hostname==3.5.0.1
  bdist-mpkg==0.4.4
  beautifulsoup4==4.4.1
  bonjour-py==0.3
  certifi==2016.2.28
  cssselect==0.9.1
  decorator==4.0.9
  functools32==3.2.3.post2
  gnureadline==6.3.3
  ipykernel==4.3.1
  ipython==4.1.2
  ipython-genutils==0.1.0
  ipywidgets==4.1.1
  Jinja2==2.8
  jsonschema==2.5.1
  jupyter==1.0.0
  jupyter-client==4.1.1
  jupyter-console==4.1.1
  jupyter-core==4.0.6
  lxml==3.5.0
  macholib==1.5
  MarkupSafe==0.23
  matplotlib==1.1.1
  mistune==0.7.2
  modulegraph==0.10.1
  nbconvert==4.1.0
  nbformat==4.0.1
  notebook==4.1.0
  numpy==1.10.4
  path.py==8.1.2
  pexpect==4.0.1
  pickleshare==0.6
  protobuf==3.0.0b2
  ptyprocess==0.5.1
  py2app==0.7.1
  pyasn1==0.1.9
  pyasn1-modules==0.0.8
  Pygments==2.1.3
  PyInstaller==3.1.1
  pyobjc-core==2.3.2a0
  pyobjc-framework-AddressBook==2.3.2a0
  pyobjc-framework-AppleScriptKit==2.3.2a0
  pyobjc-framework-AppleScriptObjC==2.3.2a0
  pyobjc-framework-Automator==2.3.2a0
  pyobjc-framework-CFNetwork==2.3.2a0
  pyobjc-framework-Cocoa==2.3.2a0
  pyobjc-framework-Collaboration==2.3.2a0
  pyobjc-framework-CoreData==2.3.2a0
  pyobjc-framework-CoreLocation==2.3.2a0
  pyobjc-framework-CoreText==2.3.2a0
  pyobjc-framework-DictionaryServices==2.3.2a0
  pyobjc-framework-ExceptionHandling==2.3.2a0
  pyobjc-framework-FSEvents==2.3.2a0
  pyobjc-framework-InputMethodKit==2.3.2a0
  pyobjc-framework-InstallerPlugins==2.3.2a0
  pyobjc-framework-InstantMessage==2.3.2a0
  pyobjc-framework-InterfaceBuilderKit==2.3.2a0
  pyobjc-framework-LatentSemanticMapping==2.3.2a0
  pyobjc-framework-LaunchServices==2.3.2a0
  pyobjc-framework-Message==2.3.2a0
  pyobjc-framework-OpenDirectory==2.3.2a0
  pyobjc-framework-PreferencePanes==2.3.2a0
  pyobjc-framework-PubSub==2.3.2a0
  pyobjc-framework-QTKit==2.3.2a0
  pyobjc-framework-Quartz==2.3.2a0
  pyobjc-framework-ScreenSaver==2.3.2a0
  pyobjc-framework-ScriptingBridge==2.3.2a0
  pyobjc-framework-SearchKit==2.3.2a0
  pyobjc-framework-ServiceManagement==2.3.2a0
  pyobjc-framework-SyncServices==2.3.2a0
  pyobjc-framework-SystemConfiguration==2.3.2a0
  pyobjc-framework-WebKit==2.3.2a0
  pyobjc-framework-XgridFoundation==2.3.2a0
  pyOpenSSL==0.13
  PyRSS2Gen==1.0.0
  python-dateutil==1.5
  pytz===2012d
  pyzmq==15.2.0
  qtconsole==4.2.0
  queuelib==1.4.2
  scikit-learn==0.17.1
  scipy==0.17.0
  Scrapy==1.0.5
  selenium==2.52.0
  service-identity==16.0.0
  simplegeneric==0.8.1
  singledispatch==3.4.0.3
  six==1.10.0
  tensorflow==0.7.1
  terminado==0.6
  tornado==4.3
  traitlets==4.1.0
  Twisted==12.2.0
  w3lib==1.13.0
  xattr==0.6.4
  zope.interface==3.8.0
  </code></pre>
  
  <p>I've Python 2.7 and OSX 10.9.5.
  What do I have to do in order to get things work?</p>