> Does anyone know what might be the problem with the
> datelocator() as I've done it?
If you look at the documentation for the DateLocator
you'll see that it takes a single argument in the init function which
is a timezone. You are passing it (min-max)/8.0 which in my guess
does not evaluate to a timezone unless you are deep into overload
DateLocator is base class and you will need to instantiate one of the
derived classes (eg MonthLocator). What plot_date does is inspect the
date range and try to make an intelligent guess about which kind of
locator you need. I just factored this code into a reusable date
locator/formatter factory function which is in CVS
Checking in lib/matplotlib/dates.py;
/cvsroot/matplotlib/matplotlib/lib/matplotlib/dates.py,v <-- dates.py
new revision: 1.12; previous revision: 1.11
I'll post it here in case you don't have access to CVS and just want
to plug it into your application
from matplotlib.dates import YearLocator, MonthLocator, WeekdayLocator, \
DayLocator, HourLocator, MinuteLocator, DateFormatter
def date_ticker_factory(span, tz=None, numticks=5):
Create a date locator with numticks (approx) and a date formatter
for span in days. Return value is (locator, formatter)
if span==0: span = 1/24.
minutes = span*24*60
hours = span*24
days = span
weeks = span/7.
months = span/31. # approx
years = span/365.
locator = YearLocator(int(years/numticks), tz=tz) # define
fmt = '%Y'
locator = MonthLocator(tz=tz)
fmt = '%b %Y'
locator = WeekdayLocator(tz=tz)
fmt = '%a, %b %d'
locator = DayLocator(interval=int(math.ceil(days/numticks)), tz=tz)
fmt = '%b %d'
locator = HourLocator(interval=int(math.ceil(hours/numticks)), tz=tz)
fmt = '%H:%M\n%b %d'
locator = MinuteLocator(interval=int(math.ceil(minutes/numticks)), tz=tz)
fmt = '%H:%M:%S'
locator = MinuteLocator(tz=tz)
fmt = '%H:%M:%S'
formatter = DateFormatter(fmt, tz=tz)
return locator, formatter
locator, formatter = date_ticker_factory(2000, numticks=8)
print locator, formatter