'*minticks* is the minimum number of ticks desired, which is used to
select the type of ticking (yearly, monthly, etc.).
*maxticks* is the maximum number of ticks desired, which controls
any interval between ticks (ticking every other, every 3, etc.).
For really fine-grained control, this can be a dictionary mapping
individual rrule frequency constants (YEARLY, MONTHLY, etc.)
to their own maximum number of ticks.  This can be used to keep
the number of ticks appropriate to the format chosen in
:class:`AutoDateFormatter`. Any frequency not specified in this
dictionary is given a default value.
*tz* is a :class:`tzinfo` instance.
*interval_multiples* is a boolean that indicates whether ticks
should be chosen to be multiple of the interval. This will lock
ticks to \'nicer\' locations. For example, this will force the
ticks to be at hours 0,6,12,18 when hourly ticking is done at
6 hour intervals.
The AutoDateLocator has an interval dictionary that maps the
frequency of the tick (a constant from dateutil.rrule) and a
multiple allowed for that ticking.  The default looks like this::
self.intervald = {
YEARLY  : [1, 2, 4, 5, 10, 20, 40, 50, 100, 200, 400, 500,
1000, 2000, 4000, 5000, 10000],
MONTHLY : [1, 2, 3, 4, 6],
DAILY   : [1, 2, 3, 7, 14],
HOURLY  : [1, 2, 3, 4, 6, 12],
MINUTELY: [1, 5, 10, 15, 30],
SECONDLY: [1, 5, 10, 15, 30],
MICROSECONDLY: [1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, 2000,
5000, 10000, 20000, 50000, 100000, 200000, 500000,
1000000],
The interval is used to specify multiples that are appropriate for
the frequency of ticking. For instance, every 7 days is sensible
for daily ticks, but for minutes/seconds, 15 or 30 make sense.
You can customize this dictionary by doing::
locator = AutoDateLocator()
locator.intervald[HOURLY] = [3] # only show every 3 hours'

def __init__(self, tz=None, minticks=5, maxticks=None, interval_multiples=False):

    DateLocator.__init__(self, tz)
    self._locator = YearLocator()
    self._freq = YEARLY
    self._freqs = [YEARLY, MONTHLY, DAILY, HOURLY, MINUTELY, SECONDLY, MICROSECONDLY]
    self.minticks = minticks
    self.maxticks = {YEARLY: 11, MONTHLY: 12, DAILY: 11, HOURLY: 12, MINUTELY: 11, SECONDLY: 11, MICROSECONDLY: 8}
    if (maxticks is not None):
        try:
            self.maxticks.update(maxticks)
        except TypeError:
            self.maxticks = dict.fromkeys(self._freqs, maxticks)
    self.interval_multiples = interval_multiples
    self.intervald = {YEARLY: [1, 2, 4, 5, 10, 20, 40, 50, 100, 200, 400, 500, 1000, 2000, 4000, 5000, 10000], MONTHLY: [1, 2, 3, 4, 6], DAILY: [1, 2, 3, 7, 14, 21], HOURLY: [1, 2, 3, 4, 6, 12], MINUTELY: [1, 5, 10, 15, 30], SECONDLY: [1, 5, 10, 15, 30], MICROSECONDLY: [1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, 2000, 5000, 10000, 20000, 50000, 100000, 200000, 500000, 1000000]}
    self._byranges = [None, range(1, 13), range(1, 32), range(0, 24), range(0, 60), range(0, 60), None]
