[matplotlib-devel] AutoDateFormatter/AutoDateLocator

Have you checked scikits.timeseries.lib.plotlib ? We provide some functions that adapt the ticks to the frequency of you base series, but also according to the range of the axes. For example, if you work with a 100-y daily timeseries, you'll have major ticks every 5 years if you plot the whole series, every month if you plot or zoom on one year only, etc.
it may be worthwhile to give it a try. I'd be happy to help adapting our code to remove the dependency on scikits.timeseries if needed...


On Oct 16, 2009, at 2:59 PM, Ryan May wrote:

On Wed, Oct 14, 2009 at 3:59 PM, John Hunter <jdh2358@...287...> > wrote:

I don't have a strong opinion on this -- making it more customizable
is a good thing -- this came up at scipy as well, where I contributed
a patch to make the AutoDateFormatter a little more customizable by
exposing a scaled dictionary mapping the scale to a format string. As
long as the extension to the AutoDateLocator preserves the core
functionality, I say have at it.

Here's a patch that implements the ideas I have. To the best of my
ability, it preserves the same behavior as before, it just opens it up
to configuration by the user instead of being hard-coded. It adds:

1) Configuring the minimum number of ticks, which determines whether
to do yearly, monthly, etc. ticking

2) Configuring the maximum number of ticks, which is used to select
what interval of ticking to use. This is actually
done on a per-frequency basis. This helps to keep in line with
previous behavior and is useful for keeping tick spacing in line with
what the label would be for a given frequency. The user can also
simply pass an integer that
gives the maximum for all frequencies.

3) A dictionary of intervals corresponding to each frequency. This
keeps the previous functionality of appropriate intervals for each
frequency, but also opens it up to user configuration.

4) Optional ticking on multiples of the interval. Previously, if you
were ticking with, say, 10 minute intervals, and the range happened to
start at 33 minutes, you'd get ticks at 33, 43, 53, etc. With this
flag set, the ticks instead end up at 40, 50, 0, 10, etc.

I'd appreciate anyone looking this over for any glaring problems
before I check this in. I've done my best to preserve old
functionality, though I'm still working on getting the unit tests to
run here. It also passes my own testing here when I fiddle with the
new knobs that have been exposed. My one question is: how important
is keeping API compatibility? The constructor tries to follow the
convention of the rest of the module (tz is last or nearly so), but
this breaks compatibility (where tz was the only argument). Also, to
me, it would be nice to tick multiples of the interval by default.