title: How to change default Anaconda python environment
body: <p>I've installed Anaconda and created two extra environments: py3k (which holds Python 3.3) and py34 (which holds Python 3.4). Besides those, I have a default environment named 'root' which the Anaconda installer created by default and which holds Python 2.7. This last one is the default, whenever I launch 'ipython' from the terminal it gives me version 2.7. In order to work with Python 3.4, I need to issue the commands (in the shell)</p>
  
  <pre><code>source activate py34
  ipython
  </code></pre>
  
  <p>which change the default environment to Python 3.4. This works fine, but it's annoying since most of the time I work on Python 3.4, instead of Python 2.7 (which I hold for teaching purposes, it's a rather long story). Anyway, I'll like to know how to change the default environment to Python 3.4, bearing in mind that I don't want to reinstall everything from scratch.  </p>