Dwr/better error handling (#8)

* Better error handling if openmp not available.

* Add requirement on openmp

README.md

@@ -27,6 +27,11 @@ This library has been added to pypi as tsne-mp
 pip install tsne-mp
 ```
 
+It requires openmp support.
+* OSX - `brew install libomp`
+* linux - 'sudo apt-get install libgomp1'
+* Windows - Included with Visual Studio C++
+
 ## Usage
 
 Basic usage:

tsne/__init__.py

@@ -2,8 +2,24 @@
 from __future__ import division
 import numpy as np
 import scipy.linalg as la
-from tsne.bh_sne import BH_SNE
-from tsne.bh_sne_3d import BH_SNE_3D
+try:
+    from tsne.bh_sne import BH_SNE
+    from tsne.bh_sne_3d import BH_SNE_3D
+except ImportError as e:
+    import sys
+    if sys.platform == 'darwin':
+        raise ImportError('''
+Unable to import likely due to missing openmp. Try: 'brew install libomp'
+''') from e
+    elif sys.platform == 'win32':
+        raise ImportError('''
+Unable to import likely due to missing openmp. Ensure openmp support is installed.'
+        ''') from e
+    else:
+        raise ImportError('''
+Unable to import likely due to missing openmp. Try: 'sudo apt-get install libgomp1'
+        ''') from e
+
 
 def bh_sne(data, pca_d=None, d=2, perplexity=30., theta=0.5,
            random_state=None, copy_data=False, init=None,