Do I have to install numpy, spicy again for python3?
Yes you need to install them using pip3 as well as python3.4 bundles pip in along side of python
I have brew install python2 for OsX, then I install numpy, scipy using pip install.
I also need python3, so I brew install python3, but when I import numpy under python3, import error occurs.
I known I can fix this by install numpy using pip3 install numpy, but do I have to do this? Since I have the package already installed for python2, can I just tell python3 where it is and then use it?