mpi4py can once again be installed via conda rather than pip, as Anaconda have fixed bug (https://github.com/conda/conda/issues/2277)

conda_env.yml

@@ -9,12 +9,12 @@ dependencies:
 - h5py
 - jupyter
 - matplotlib
+- mpi4py
 - numpy
 - psutil
 - pyqt=4.11.4
 - scipy
 
 - pip:
-  - mpi4py
   - terminaltables
-  - tqdm
+  - tqdm