Virtual Environments In Python

In one of my last posts I installed python packages with pip and the --user switch. This worked, but sucked. I was too stupid to manage packages with conda and would not even advise my enemies to do so. But I found a better way.

There is a tool called vitualenv which can set up virtual Python instances. It works in userspace and so does not interfere with my package manager. This may sound like an obvious thing to you, and perhaps I am noobish for mentioning it, but I hope it helps someone. Remember, I wanted to install zipline. So I did a

$ virtualenv ~/venv/zipline
New python executable in /home/hjgk/venv/zipline/bin/python
Installing setuptools, pip...done.

which set up a new virtual environment in ~/venv/zipline. Note that zipline is not only the name of the package I want to install, but also the name of my virtual environment.

Then I switched to the new environment with

$ source ~/venv/zipline/bin/activate

and my prompt was prepended with (zipline), because I am now in my new virtual environment where I can install packages like a lunatic.

(zipline)$ pip install numpy&&pip install zipline

Now it is compiling and throwing some warnings, but finally it finishes. At least in my case.

Then I tested everything according to the zipline docs

(zipline)$ python ~/venv/zipline/bin/run_algo.py -f dual_mavg.py --symbols AAPL --start 2011-1-1 --end 2012-1-1 -o dma.pickle

And it worked!

Note that I have to write ~/venv/zipline/bin/run_algo.py, since I have not found out how to set a path in python, as in one of my last posts. But at least I am able to install packages without arguing with aptitude.