How to change default Anaconda python environment
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)
source activate py34
ipython
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.
Answer
If you just want to change to another environment, use
source activate environment-name
(you can create environment-name with `conda create)
Typically it's best to just create new environments. However, if you really want to change the Python version in the default environment, you can do so as follows:
First, make sure you have the latest version of conda by running
conda update conda
Then run
conda install python=3.5
This will attempt to update all your packages in your root environment to Python 3 versions. If it is not possible (e.g., because some package is not built for Python 3.5), it will give you an error message indicating which package(s) caused the issue.
If you installed packages with pip, you'll have to reinstall them.