You have created the box, but you’re still out of it. The virtual environment is physically located in ~/box. Again, if you screw something up, you can just delete the box and start again. You can have different boxes for different projects, or a single box for all your python stuff. Python’s virtual environments are kind of separate boxes, where you can install modules and packages locally. The easiest way to safely install python on a MAC is homebrew. Homebrew installs a new version of python (by default the latest 2.x version available) and set is as default.

I will also stay with python 2 for now, but see below for some info on python 3 (see also here for more). However, it is advisable to install a local distribution and do your scientific stuff from there… If you screw something up, you can just delete everything and your OS is safe. Most (if not all) unix systems already come with a python distribution installed. This is a step-by-step guide to the best way I found to install and use python for science, the easy (less hackable) way comes first, and the long way comes next. All sort of scientific algorithms are already there (written and debugged!), you just have to use them. Python is cool, especially if you a scientist.

How to install curl python