don't register pandas mpl unit converters upon import

[changhiskhan]

register it upon plotting?

http://stackoverflow.com/questions/13988111/importing-pandas-in-python-changes-how-matplotlib-handles-datetime-objects

[wesm]

Is this critical for 0.10.1?

[changhiskhan]

no, it's also a slog. lots of separate plotting functions that need to register the unit converters

[ruidc]

What about putting them all in a single registration method that's only called when plotting?

[wesm]

Pushing past 0.11

[jreback]

@cpcloud is still an issue?

[cpcloud]

those are still registered...so, yes

[cpcloud]

i can take a look

[cpcloud]

this is super low priority ... pushing to 0.14

[rhattersley]

this is super low priority

But also super annoying if you're on the receiving end of it. You can get away with it if you're only using pandas for your plots, but this kind of side-effect is really not pleasant when pandas is used as one component amongst several.

register it upon plotting?

This is only a small improvement - the basic problem of global side-effects still exists.

---

So I'd much rather make it an explicit user action (with another action available to undo it), and/or a temporary state change that only persists for the lifetime of the pandas plotting routines.

For example, an explicit approach might be:

# <user code>
with pandas.use_nice_date_formats():
    plt.plot(...)

Whereas the automatic temporary state change might look (logically) like:

# <pandas implementation>
class Series(...):
    def plot(...):
        with pandas.use_nice_date_formats():
            plt.plot(...)

# <user code>
ts.plot()