plot_date with non-UTC timezone


I have noticed that matplotlib's plot_date() function occasionally
places the label at the date (or month or year) end instead of the
beginning. I attach a script illustrating the problem: I plot a range
of y-values for a range of dates. The y-value 29 should be associated
with 11 Nov 2011. In figure 1, left I am using UTC and everything is
fine. In the right plot I am using the 'Europe/London' timezone and
now the graph suggests that the y-value 29 is associated with 10 Nov
2011. When moving the mouse over the plot and watching the status bar
at the bottom it suggest that indeed the label is placed at the
date-end rather than the beginning. I have observed the same behaviour
with month and year labels being shifted in non-UTC timezones.

I have my time data as POSIX timestamps, so using datetime objects in
plotting directly is not a (convenient) option. (In the sample code I
use datetime only to generate example POSIX timestamps at midnight).
Instead I would like to rely on the epoch2num() helper function
supplied by matplotlib.

I am using matplotlib-1.1.0, numpy-1.6.1.

Any help appreciated,
thanks, Nils. (3.01 KB)