It would be great to have autocompletion on rcParams (or settings) in IPython, so you could do

settings["fon<TAB>"]

and get a list of all keys containing the string "fon".
This would be another tool to get people modifying settings.

Currently there is no completion on dictionary keys in IPython -- I am hoping to implement this this week.

However, a nicer solution, in my opinion, is attribute access, so you could do e.g.

settings.xtick.color = 'b'

This is easy to implement by hand. But it turns out that it is already implemented in IPython! Even if in a slightly obscure (but super-general so nothing done by hand) way:

from matplotlib import rcParams
from IPython.config import Config

settings = Config(rcParams)

You can now automatically use the settings.xtick.color syntax and completion!:

settings.xtic<TAB>

gives a list of all the settings starting with xtic. (See below for more completion magic).

However, there is a problem with the names of the rcParams keys using . as a separator, namely that doing

settings.xtick.<TAB>

no longer completes anything. This is because it is treating settings.xtick as a subdictionary or subclass.

There are 2 possible solutions:

1. Change the names of the settings keys, e.g. to xtick_minor_pad. Yuck.
2. An excellent solution -- not just for this autocompletion problem -- is the following:

Really turn the sequence of names including .s in the string in the attribute-access pattern into real sub-dictionaries of rcParams.

Of course, this makes the dictionary key syntax horrible, but there would be no longer be any need for it -- we would just switch over wholesale to the . attribute syntax.

Of course, this breaks some backward compatibility, but it gives a much more logical structure to rcParams as a whole.
[And, thinking about it, it should be possible to rewrite the dictionary access functions so that the old key accesses still work!]

Of course, the magic going on in the IPython.config module is easily extractable straight in to rcParams, in case somebody is worried that this depends on IPython.

------- [Comments on future IPython command completion possibilities below]

In fact, I have a mod for IPython's command completion which completes any word containing the letters that you type in a certain order. Here is the output for

settings.fon<TAB>:

settings.figure.frameon           settings.legend.fontsize
settings.figure.max_open_warning  settings.legend.frameon
settings.font.cursive             settings.mathtext.fontset
settings.font.family              settings.pdf.compression
settings.font.fantasy             settings.pdf.fonttype
settings.font.monospace           settings.pdf.use14corefonts
settings.font.sans-serif          settings.pgf.rcfonts
settings.font.serif               settings.ps.fonttype
settings.font.size                settings.savefig.extension
settings.font.stretch             settings.savefig.frameon
settings.font.style               settings.savefig.orientation
settings.font.variant             settings.svg.fonttype
settings.font.weight              

It includes things that don't start with fon but contain the sequence of characters f, o, n in that order.

An alternative is to just search for the word fon, without splitting up the characters.
I hope to submit an IPython pull request soon. It will be possible to change between these different types of completion mechanism with a standard IPython configuration method.