Ternary

These are my minor updates to code implementing ternary projections developed by Kevin Davies in 2011 (https://github.com/kdavies4/matplotlib/tree/ternary2); my changes simply make his code work with recent versions of matplotlib.

Ternary plots are a convenient way to visualize the three-dimensional unit simplex; I'm attaching a simple example from my own research on three-player games.
![numbers_game_with_dummy](https://cloud.githubusercontent.com/assets/605452/5146006/d416256c-719f-11e4-84e9-118cbe939dd7.png)

I wouldn't worry about the "as a function" issue at this point. In fact, I
thought that the plan was to have plotting objects (but that is a
discussion for another thread).

On Fri, Nov 21, 2014 at 3:59 PM, Kevin Davies <notifications@github.com>
wrote:

> In lib/matplotlib/ternary.py:
>
> > +"""Class to create a ternary plot using matplotlib projections
> > +"""
> > +__author__ = "Kevin L. Davies"
> > +__version__ = "2011/10/12"
> > +__license__ = "BSD"
> > +
> > +import matplotlib.pyplot as plt # **Is this acceptable?
> > +
> > +from matplotlib import rcParams
> > +
> > +# **To do:
> > +#   1. Clean up the procedure for setting the colorbar's location.
> > +#   2. Support all of the applicable axes methods
> > +#      (http://matplotlib.sourceforge.net/api/axes_api.html).
> > +
> > +class Ternary():
>
> It's been a while since I wrote the ternary class, but I'll try to help.
> If we're to change it to a plotting function, I'd like to have consensus
> though.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/matplotlib/matplotlib/pull/3828/files#r20741492>.
>