_converter.py

import warnings
from datetime import datetime, timedelta
import datetime as pydt
import numpy as np

from dateutil.relativedelta import relativedelta

import matplotlib.units as units
import matplotlib.dates as dates

from matplotlib.ticker import Formatter, AutoLocator, Locator
from matplotlib.transforms import nonsingular

from pandas.core.dtypes.common import (
    is_float, is_integer,
    is_integer_dtype,
    is_float_dtype,
    is_datetime64_ns_dtype,
    is_period_arraylike,
    is_nested_list_like
)
from pandas.core.dtypes.generic import ABCSeries

from pandas.compat import lrange
import pandas.compat as compat
import pandas._libs.lib as lib
import pandas.core.common as com
from pandas.core.index import Index

from pandas.core.indexes.datetimes import date_range
import pandas.core.tools.datetimes as tools
import pandas.tseries.frequencies as frequencies
from pandas.tseries.frequencies import FreqGroup
from pandas.core.indexes.period import Period, PeriodIndex

from pandas.plotting._compat import _mpl_le_2_0_0

# constants
HOURS_PER_DAY = 24.
MIN_PER_HOUR = 60.
SEC_PER_MIN = 60.

SEC_PER_HOUR = SEC_PER_MIN * MIN_PER_HOUR
SEC_PER_DAY = SEC_PER_HOUR * HOURS_PER_DAY

MUSEC_PER_DAY = 1e6 * SEC_PER_DAY

_WARN = True  # Global for whether pandas has registered the units explicitly
_mpl_units = {}  # Cache for units overwritten by us


def get_pairs():
    pairs = [
        (lib.Timestamp, DatetimeConverter),
        (Period, PeriodConverter),
        (pydt.datetime, DatetimeConverter),
        (pydt.date, DatetimeConverter),
        (pydt.time, TimeConverter),
        (np.datetime64, DatetimeConverter),
    ]
    return pairs


def register(explicit=True):
    """Register Pandas Formatters and Converters with matplotlib

    This function modifies the global ``matplotlib.units.registry``
    dictionary. Pandas adds custom converters for

    * pd.Timestamp
    * pd.Period
    * np.datetime64
    * datetime.datetime
    * datetime.date
    * datetime.time

    See Also
    --------
    deregister_matplotlib_converter
    """
    # Renamed in pandas.plotting.__init__
    global _WARN

    if explicit:
        _WARN = False

    pairs = get_pairs()
    for type_, cls in pairs:
        converter = cls()
        if type_ in units.registry:
            previous = units.registry[type_]
            _mpl_units[type_] = previous
        units.registry[type_] = converter


def deregister():
    """Remove pandas' formatters and converters

    Removes the custom converters added by :func:`register`. This
    attempts to set the state of the registry back to the state before
    pandas registered its own units. Converters for pandas' own types like
    Timestamp and Period are removed completely. Converters for types
    pandas overwrites, like ``datetime.datetime``, are restored to their
    original value.

    See Also
    --------
    deregister_matplotlib_converters
    """
    # Renamed in pandas.plotting.__init__
    for type_, cls in get_pairs():
        # We use type to catch our classes directly, no inheritance
        if type(units.registry.get(type_)) is cls:
            units.registry.pop(type_)

    # restore the old keys
    for unit, formatter in _mpl_units.items():
        if type(formatter) not in {DatetimeConverter, PeriodConverter,
                                   TimeConverter}:
            # make it idempotent by excluding ours.
            units.registry[unit] = formatter


def _check_implicitly_registered():
    global _WARN

    if _WARN:
        msg = ("Using an implicitly registered datetime converter for a "
               "matplotlib plotting method. The converter was registered "
               "by pandas on import. Future versions of pandas will require "
               "you to explicitly register matplotlib converters.\n\n"
               "To register the converters:\n\t"
               ">>> from pandas.plotting import register_matplotlib_converters"
               "\n\t"
               ">>> register_matplotlib_converters()")
        warnings.warn(msg, FutureWarning)
        _WARN = False


def _to_ordinalf(tm):
    tot_sec = (tm.hour * 3600 + tm.minute * 60 + tm.second +
               float(tm.microsecond / 1e6))
    return tot_sec


def time2num(d):
    if isinstance(d, compat.string_types):
        parsed = tools.to_datetime(d)
        if not isinstance(parsed, datetime):
            raise ValueError('Could not parse time %s' % d)
        return _to_ordinalf(parsed.time())
    if isinstance(d, pydt.time):
        return _to_ordinalf(d)
    return d


class TimeConverter(units.ConversionInterface):

    @staticmethod
    def convert(value, unit, axis):
        valid_types = (str, pydt.time)
        if (isinstance(value, valid_types) or is_integer(value) or
                is_float(value)):
            return time2num(value)
        if isinstance(value, Index):
            return value.map(time2num)
        if isinstance(value, (list, tuple, np.ndarray, Index)):
            return [time2num(x) for x in value]
        return value

    @staticmethod
    def axisinfo(unit, axis):
        if unit != 'time':
            return None

        majloc = AutoLocator()
        majfmt = TimeFormatter(majloc)
        return units.AxisInfo(majloc=majloc, majfmt=majfmt, label='time')

    @staticmethod
    def default_units(x, axis):
        return 'time'


# time formatter
class TimeFormatter(Formatter):

    def __init__(self, locs):
        self.locs = locs

    def __call__(self, x, pos=0):
        fmt = '%H:%M:%S'
        s = int(x)
        ms = int((x - s) * 1e3)
        us = int((x - s) * 1e6 - ms)
        m, s = divmod(s, 60)
        h, m = divmod(m, 60)
        _, h = divmod(h, 24)
        if us != 0:
            fmt += '.%6f'
        elif ms != 0:
            fmt += '.%3f'

        return pydt.time(h, m, s, us).strftime(fmt)


# Period Conversion


class PeriodConverter(dates.DateConverter):

    @staticmethod
    def convert(values, units, axis):
        if is_nested_list_like(values):
            values = [PeriodConverter._convert_1d(v, units, axis)
                      for v in values]
        else:
            values = PeriodConverter._convert_1d(values, units, axis)
        return values

    @staticmethod
    def _convert_1d(values, units, axis):
        if not hasattr(axis, 'freq'):
            raise TypeError('Axis must have `freq` set to convert to Periods')
        valid_types = (compat.string_types, datetime,
                       Period, pydt.date, pydt.time)
        if (isinstance(values, valid_types) or is_integer(values) or
                is_float(values)):
            return get_datevalue(values, axis.freq)
        if isinstance(values, PeriodIndex):
            return values.asfreq(axis.freq)._values
        if isinstance(values, Index):
            return values.map(lambda x: get_datevalue(x, axis.freq))
        if is_period_arraylike(values):
            return PeriodIndex(values, freq=axis.freq)._values
        if isinstance(values, (list, tuple, np.ndarray, Index)):
            return [get_datevalue(x, axis.freq) for x in values]
        return values


def get_datevalue(date, freq):
    if isinstance(date, Period):
        return date.asfreq(freq).ordinal
    elif isinstance(date, (compat.string_types, datetime,
                           pydt.date, pydt.time)):
        return Period(date, freq).ordinal
    elif (is_integer(date) or is_float(date) or
          (isinstance(date, (np.ndarray, Index)) and (date.size == 1))):
        return date
    elif date is None:
        return None
    raise ValueError("Unrecognizable date '%s'" % date)


def _dt_to_float_ordinal(dt):
    """
    Convert :mod:`datetime` to the Gregorian date as UTC float days,
    preserving hours, minutes, seconds and microseconds.  Return value
    is a :func:`float`.
    """
    if (isinstance(dt, (np.ndarray, Index, ABCSeries)
                   ) and is_datetime64_ns_dtype(dt)):
        base = dates.epoch2num(dt.asi8 / 1.0E9)
    else:
        base = dates.date2num(dt)
    return base


# Datetime Conversion
class DatetimeConverter(dates.DateConverter):

    @staticmethod
    def convert(values, unit, axis):
        # values might be a 1-d array, or a list-like of arrays.
        _check_implicitly_registered()
        if is_nested_list_like(values):
            values = [DatetimeConverter._convert_1d(v, unit, axis)
                      for v in values]
        else:
            values = DatetimeConverter._convert_1d(values, unit, axis)
        return values

    @staticmethod
    def _convert_1d(values, unit, axis):
        def try_parse(values):
            try:
                return _dt_to_float_ordinal(tools.to_datetime(values))
            except Exception:
                return values

        if isinstance(values, (datetime, pydt.date)):
            return _dt_to_float_ordinal(values)
        elif isinstance(values, np.datetime64):
            return _dt_to_float_ordinal(lib.Timestamp(values))
        elif isinstance(values, pydt.time):
            return dates.date2num(values)
        elif (is_integer(values) or is_float(values)):
            return values
        elif isinstance(values, compat.string_types):
            return try_parse(values)
        elif isinstance(values, (list, tuple, np.ndarray, Index)):
            if isinstance(values, Index):
                values = values.values
            if not isinstance(values, np.ndarray):
                values = com._asarray_tuplesafe(values)

            if is_integer_dtype(values) or is_float_dtype(values):
                return values

            try:
                values = tools.to_datetime(values)
                if isinstance(values, Index):
                    values = _dt_to_float_ordinal(values)
                else:
                    values = [_dt_to_float_ordinal(x) for x in values]
            except Exception:
                values = _dt_to_float_ordinal(values)

        return values

    @staticmethod
    def axisinfo(unit, axis):
        """
        Return the :class:`~matplotlib.units.AxisInfo` for *unit*.

        *unit* is a tzinfo instance or None.
        The *axis* argument is required but not used.
        """
        tz = unit

        majloc = PandasAutoDateLocator(tz=tz)
        majfmt = PandasAutoDateFormatter(majloc, tz=tz)
        datemin = pydt.date(2000, 1, 1)
        datemax = pydt.date(2010, 1, 1)

        return units.AxisInfo(majloc=majloc, majfmt=majfmt, label='',
                              default_limits=(datemin, datemax))


class PandasAutoDateFormatter(dates.AutoDateFormatter):

    def __init__(self, locator, tz=None, defaultfmt='%Y-%m-%d'):
        dates.AutoDateFormatter.__init__(self, locator, tz, defaultfmt)
        # matplotlib.dates._UTC has no _utcoffset called by pandas
        if self._tz is dates.UTC:
            self._tz._utcoffset = self._tz.utcoffset(None)

        # For mpl > 2.0 the format strings are controlled via rcparams
        # so do not mess with them.  For mpl < 2.0 change the second
        # break point and add a musec break point
        if _mpl_le_2_0_0():
            self.scaled[1. / SEC_PER_DAY] = '%H:%M:%S'
            self.scaled[1. / MUSEC_PER_DAY] = '%H:%M:%S.%f'


class PandasAutoDateLocator(dates.AutoDateLocator):

    def get_locator(self, dmin, dmax):
        'Pick the best locator based on a distance.'
        _check_implicitly_registered()
        delta = relativedelta(dmax, dmin)

        num_days = (delta.years * 12.0 + delta.months) * 31.0 + delta.days
        num_sec = (delta.hours * 60.0 + delta.minutes) * 60.0 + delta.seconds
        tot_sec = num_days * 86400. + num_sec

        if abs(tot_sec) < self.minticks:
            self._freq = -1
            locator = MilliSecondLocator(self.tz)
            locator.set_axis(self.axis)

            locator.set_view_interval(*self.axis.get_view_interval())
            locator.set_data_interval(*self.axis.get_data_interval())
            return locator

        return dates.AutoDateLocator.get_locator(self, dmin, dmax)

    def _get_unit(self):
        return MilliSecondLocator.get_unit_generic(self._freq)


class MilliSecondLocator(dates.DateLocator):

    UNIT = 1. / (24 * 3600 * 1000)

    def __init__(self, tz):
        dates.DateLocator.__init__(self, tz)
        self._interval = 1.

    def _get_unit(self):
        return self.get_unit_generic(-1)

    @staticmethod
    def get_unit_generic(freq):
        unit = dates.RRuleLocator.get_unit_generic(freq)
        if unit < 0:
            return MilliSecondLocator.UNIT
        return unit

    def __call__(self):
        # if no data have been set, this will tank with a ValueError
        _check_implicitly_registered()
        try:
            dmin, dmax = self.viewlim_to_dt()
        except ValueError:
            return []

        if dmin > dmax:
            dmax, dmin = dmin, dmax
        # We need to cap at the endpoints of valid datetime

        # TODO(wesm) unused?
        # delta = relativedelta(dmax, dmin)
        # try:
        #     start = dmin - delta
        # except ValueError:
        #     start = _from_ordinal(1.0)

        # try:
        #     stop = dmax + delta
        # except ValueError:
        #     # The magic number!
        #     stop = _from_ordinal(3652059.9999999)

        nmax, nmin = dates.date2num((dmax, dmin))

        num = (nmax - nmin) * 86400 * 1000
        max_millis_ticks = 6
        for interval in [1, 10, 50, 100, 200, 500]:
            if num <= interval * (max_millis_ticks - 1):
                self._interval = interval
                break
            else:
                # We went through the whole loop without breaking, default to 1
                self._interval = 1000.

        estimate = (nmax - nmin) / (self._get_unit() * self._get_interval())

        if estimate > self.MAXTICKS * 2:
            raise RuntimeError(('MillisecondLocator estimated to generate %d '
                                'ticks from %s to %s: exceeds Locator.MAXTICKS'
                                '* 2 (%d) ') %
                               (estimate, dmin, dmax, self.MAXTICKS * 2))

        freq = '%dL' % self._get_interval()
        tz = self.tz.tzname(None)
        st = _from_ordinal(dates.date2num(dmin))  # strip tz
        ed = _from_ordinal(dates.date2num(dmax))
        all_dates = date_range(start=st, end=ed, freq=freq, tz=tz).asobject

        try:
            if len(all_dates) > 0:
                locs = self.raise_if_exceeds(dates.date2num(all_dates))
                return locs
        except Exception:  # pragma: no cover
            pass

        lims = dates.date2num([dmin, dmax])
        return lims

    def _get_interval(self):
        return self._interval

    def autoscale(self):
        """
        Set the view limits to include the data range.
        """
        dmin, dmax = self.datalim_to_dt()
        if dmin > dmax:
            dmax, dmin = dmin, dmax

        # We need to cap at the endpoints of valid datetime

        # TODO(wesm): unused?

        # delta = relativedelta(dmax, dmin)
        # try:
        #     start = dmin - delta
        # except ValueError:
        #     start = _from_ordinal(1.0)

        # try:
        #     stop = dmax + delta
        # except ValueError:
        #     # The magic number!
        #     stop = _from_ordinal(3652059.9999999)

        dmin, dmax = self.datalim_to_dt()

        vmin = dates.date2num(dmin)
        vmax = dates.date2num(dmax)

        return self.nonsingular(vmin, vmax)


def _from_ordinal(x, tz=None):
    ix = int(x)
    dt = datetime.fromordinal(ix)
    remainder = float(x) - ix
    hour, remainder = divmod(24 * remainder, 1)
    minute, remainder = divmod(60 * remainder, 1)
    second, remainder = divmod(60 * remainder, 1)
    microsecond = int(1e6 * remainder)
    if microsecond < 10:
        microsecond = 0  # compensate for rounding errors
    dt = datetime(dt.year, dt.month, dt.day, int(hour), int(minute),
                  int(second), microsecond)
    if tz is not None:
        dt = dt.astimezone(tz)

    if microsecond > 999990:  # compensate for rounding errors
        dt += timedelta(microseconds=1e6 - microsecond)

    return dt

# Fixed frequency dynamic tick locators and formatters

# -------------------------------------------------------------------------
# --- Locators ---
# -------------------------------------------------------------------------


def _get_default_annual_spacing(nyears):
    """
    Returns a default spacing between consecutive ticks for annual data.
    """
    if nyears < 11:
        (min_spacing, maj_spacing) = (1, 1)
    elif nyears < 20:
        (min_spacing, maj_spacing) = (1, 2)
    elif nyears < 50:
        (min_spacing, maj_spacing) = (1, 5)
    elif nyears < 100:
        (min_spacing, maj_spacing) = (5, 10)
    elif nyears < 200:
        (min_spacing, maj_spacing) = (5, 25)
    elif nyears < 600:
        (min_spacing, maj_spacing) = (10, 50)
    else:
        factor = nyears // 1000 + 1
        (min_spacing, maj_spacing) = (factor * 20, factor * 100)
    return (min_spacing, maj_spacing)


def period_break(dates, period):
    """
    Returns the indices where the given period changes.

    Parameters
    ----------
    dates : PeriodIndex
        Array of intervals to monitor.
    period : string
        Name of the period to monitor.
    """
    current = getattr(dates, period)
    previous = getattr(dates - 1, period)
    return np.nonzero(current - previous)[0]


def has_level_label(label_flags, vmin):
    """
    Returns true if the ``label_flags`` indicate there is at least one label
    for this level.

    if the minimum view limit is not an exact integer, then the first tick
    label won't be shown, so we must adjust for that.
    """
    if label_flags.size == 0 or (label_flags.size == 1 and
                                 label_flags[0] == 0 and
                                 vmin % 1 > 0.0):
        return False
    else:
        return True


def _daily_finder(vmin, vmax, freq):
    periodsperday = -1

    if freq >= FreqGroup.FR_HR:
        if freq == FreqGroup.FR_NS:
            periodsperday = 24 * 60 * 60 * 1000000000
        elif freq == FreqGroup.FR_US:
            periodsperday = 24 * 60 * 60 * 1000000
        elif freq == FreqGroup.FR_MS:
            periodsperday = 24 * 60 * 60 * 1000
        elif freq == FreqGroup.FR_SEC:
            periodsperday = 24 * 60 * 60
        elif freq == FreqGroup.FR_MIN:
            periodsperday = 24 * 60
        elif freq == FreqGroup.FR_HR:
            periodsperday = 24
        else:  # pragma: no cover
            raise ValueError("unexpected frequency: %s" % freq)
        periodsperyear = 365 * periodsperday
        periodspermonth = 28 * periodsperday

    elif freq == FreqGroup.FR_BUS:
        periodsperyear = 261
        periodspermonth = 19
    elif freq == FreqGroup.FR_DAY:
        periodsperyear = 365
        periodspermonth = 28
    elif frequencies.get_freq_group(freq) == FreqGroup.FR_WK:
        periodsperyear = 52
        periodspermonth = 3
    else:  # pragma: no cover
        raise ValueError("unexpected frequency")

    # save this for later usage
    vmin_orig = vmin

    (vmin, vmax) = (Period(ordinal=int(vmin), freq=freq),
                    Period(ordinal=int(vmax), freq=freq))
    span = vmax.ordinal - vmin.ordinal + 1
    dates_ = PeriodIndex(start=vmin, end=vmax, freq=freq)
    # Initialize the output
    info = np.zeros(span,
                    dtype=[('val', np.int64), ('maj', bool),
                           ('min', bool), ('fmt', '|S20')])
    info['val'][:] = dates_._values
    info['fmt'][:] = ''
    info['maj'][[0, -1]] = True
    # .. and set some shortcuts
    info_maj = info['maj']
    info_min = info['min']
    info_fmt = info['fmt']

    def first_label(label_flags):
        if (label_flags[0] == 0) and (label_flags.size > 1) and \
                ((vmin_orig % 1) > 0.0):
            return label_flags[1]
        else:
            return label_flags[0]

    # Case 1. Less than a month
    if span <= periodspermonth:
        day_start = period_break(dates_, 'day')
        month_start = period_break(dates_, 'month')

        def _hour_finder(label_interval, force_year_start):
            _hour = dates_.hour
            _prev_hour = (dates_ - 1).hour
            hour_start = (_hour - _prev_hour) != 0
            info_maj[day_start] = True
            info_min[hour_start & (_hour % label_interval == 0)] = True
            year_start = period_break(dates_, 'year')
            info_fmt[hour_start & (_hour % label_interval == 0)] = '%H:%M'
            info_fmt[day_start] = '%H:%M\n%d-%b'
            info_fmt[year_start] = '%H:%M\n%d-%b\n%Y'
            if force_year_start and not has_level_label(year_start, vmin_orig):
                info_fmt[first_label(day_start)] = '%H:%M\n%d-%b\n%Y'

        def _minute_finder(label_interval):
            hour_start = period_break(dates_, 'hour')
            _minute = dates_.minute
            _prev_minute = (dates_ - 1).minute
            minute_start = (_minute - _prev_minute) != 0
            info_maj[hour_start] = True
            info_min[minute_start & (_minute % label_interval == 0)] = True
            year_start = period_break(dates_, 'year')
            info_fmt = info['fmt']
            info_fmt[minute_start & (_minute % label_interval == 0)] = '%H:%M'
            info_fmt[day_start] = '%H:%M\n%d-%b'
            info_fmt[year_start] = '%H:%M\n%d-%b\n%Y'

        def _second_finder(label_interval):
            minute_start = period_break(dates_, 'minute')
            _second = dates_.second
            _prev_second = (dates_ - 1).second
            second_start = (_second - _prev_second) != 0
            info['maj'][minute_start] = True
            info['min'][second_start & (_second % label_interval == 0)] = True
            year_start = period_break(dates_, 'year')
            info_fmt = info['fmt']
            info_fmt[second_start & (_second %
                                     label_interval == 0)] = '%H:%M:%S'
            info_fmt[day_start] = '%H:%M:%S\n%d-%b'
            info_fmt[year_start] = '%H:%M:%S\n%d-%b\n%Y'

        if span < periodsperday / 12000.0:
            _second_finder(1)
        elif span < periodsperday / 6000.0:
            _second_finder(2)
        elif span < periodsperday / 2400.0:
            _second_finder(5)
        elif span < periodsperday / 1200.0:
            _second_finder(10)
        elif span < periodsperday / 800.0:
            _second_finder(15)
        elif span < periodsperday / 400.0:
            _second_finder(30)
        elif span < periodsperday / 150.0:
            _minute_finder(1)
        elif span < periodsperday / 70.0:
            _minute_finder(2)
        elif span < periodsperday / 24.0:
            _minute_finder(5)
        elif span < periodsperday / 12.0:
            _minute_finder(15)
        elif span < periodsperday / 6.0:
            _minute_finder(30)
        elif span < periodsperday / 2.5:
            _hour_finder(1, False)
        elif span < periodsperday / 1.5:
            _hour_finder(2, False)
        elif span < periodsperday * 1.25:
            _hour_finder(3, False)
        elif span < periodsperday * 2.5:
            _hour_finder(6, True)
        elif span < periodsperday * 4:
            _hour_finder(12, True)
        else:
            info_maj[month_start] = True
            info_min[day_start] = True
            year_start = period_break(dates_, 'year')
            info_fmt = info['fmt']
            info_fmt[day_start] = '%d'
            info_fmt[month_start] = '%d\n%b'
            info_fmt[year_start] = '%d\n%b\n%Y'
            if not has_level_label(year_start, vmin_orig):
                if not has_level_label(month_start, vmin_orig):
                    info_fmt[first_label(day_start)] = '%d\n%b\n%Y'
                else:
                    info_fmt[first_label(month_start)] = '%d\n%b\n%Y'

    # Case 2. Less than three months
    elif span <= periodsperyear // 4:
        month_start = period_break(dates_, 'month')
        info_maj[month_start] = True
        if freq < FreqGroup.FR_HR:
            info['min'] = True
        else:
            day_start = period_break(dates_, 'day')
            info['min'][day_start] = True
        week_start = period_break(dates_, 'week')
        year_start = period_break(dates_, 'year')
        info_fmt[week_start] = '%d'
        info_fmt[month_start] = '\n\n%b'
        info_fmt[year_start] = '\n\n%b\n%Y'
        if not has_level_label(year_start, vmin_orig):
            if not has_level_label(month_start, vmin_orig):
                info_fmt[first_label(week_start)] = '\n\n%b\n%Y'
            else:
                info_fmt[first_label(month_start)] = '\n\n%b\n%Y'
    # Case 3. Less than 14 months ...............
    elif span <= 1.15 * periodsperyear:
        year_start = period_break(dates_, 'year')
        month_start = period_break(dates_, 'month')
        week_start = period_break(dates_, 'week')
        info_maj[month_start] = True
        info_min[week_start] = True
        info_min[year_start] = False
        info_min[month_start] = False
        info_fmt[month_start] = '%b'
        info_fmt[year_start] = '%b\n%Y'
        if not has_level_label(year_start, vmin_orig):
            info_fmt[first_label(month_start)] = '%b\n%Y'
    # Case 4. Less than 2.5 years ...............
    elif span <= 2.5 * periodsperyear:
        year_start = period_break(dates_, 'year')
        quarter_start = period_break(dates_, 'quarter')
        month_start = period_break(dates_, 'month')
        info_maj[quarter_start] = True
        info_min[month_start] = True
        info_fmt[quarter_start] = '%b'
        info_fmt[year_start] = '%b\n%Y'
    # Case 4. Less than 4 years .................
    elif span <= 4 * periodsperyear:
        year_start = period_break(dates_, 'year')
        month_start = period_break(dates_, 'month')
        info_maj[year_start] = True
        info_min[month_start] = True
        info_min[year_start] = False

        month_break = dates_[month_start].month
        jan_or_jul = month_start[(month_break == 1) | (month_break == 7)]
        info_fmt[jan_or_jul] = '%b'
        info_fmt[year_start] = '%b\n%Y'
    # Case 5. Less than 11 years ................
    elif span <= 11 * periodsperyear:
        year_start = period_break(dates_, 'year')
        quarter_start = period_break(dates_, 'quarter')
        info_maj[year_start] = True
        info_min[quarter_start] = True
        info_min[year_start] = False
        info_fmt[year_start] = '%Y'
    # Case 6. More than 12 years ................
    else:
        year_start = period_break(dates_, 'year')
        year_break = dates_[year_start].year
        nyears = span / periodsperyear
        (min_anndef, maj_anndef) = _get_default_annual_spacing(nyears)
        major_idx = year_start[(year_break % maj_anndef == 0)]
        info_maj[major_idx] = True
        minor_idx = year_start[(year_break % min_anndef == 0)]
        info_min[minor_idx] = True
        info_fmt[major_idx] = '%Y'

    return info


def _monthly_finder(vmin, vmax, freq):
    periodsperyear = 12

    vmin_orig = vmin
    (vmin, vmax) = (int(vmin), int(vmax))
    span = vmax - vmin + 1

    # Initialize the output
    info = np.zeros(span,
                    dtype=[('val', int), ('maj', bool), ('min', bool),
                           ('fmt', '|S8')])
    info['val'] = np.arange(vmin, vmax + 1)
    dates_ = info['val']
    info['fmt'] = ''
    year_start = (dates_ % 12 == 0).nonzero()[0]
    info_maj = info['maj']
    info_fmt = info['fmt']

    if span <= 1.15 * periodsperyear:
        info_maj[year_start] = True
        info['min'] = True

        info_fmt[:] = '%b'
        info_fmt[year_start] = '%b\n%Y'

        if not has_level_label(year_start, vmin_orig):
            if dates_.size > 1:
                idx = 1
            else:
                idx = 0
            info_fmt[idx] = '%b\n%Y'

    elif span <= 2.5 * periodsperyear:
        quarter_start = (dates_ % 3 == 0).nonzero()
        info_maj[year_start] = True
        # TODO: Check the following : is it really info['fmt'] ?
        info['fmt'][quarter_start] = True
        info['min'] = True

        info_fmt[quarter_start] = '%b'
        info_fmt[year_start] = '%b\n%Y'

    elif span <= 4 * periodsperyear:
        info_maj[year_start] = True
        info['min'] = True

        jan_or_jul = (dates_ % 12 == 0) | (dates_ % 12 == 6)
        info_fmt[jan_or_jul] = '%b'
        info_fmt[year_start] = '%b\n%Y'

    elif span <= 11 * periodsperyear:
        quarter_start = (dates_ % 3 == 0).nonzero()
        info_maj[year_start] = True
        info['min'][quarter_start] = True

        info_fmt[year_start] = '%Y'

    else:
        nyears = span / periodsperyear
        (min_anndef, maj_anndef) = _get_default_annual_spacing(nyears)
        years = dates_[year_start] // 12 + 1
        major_idx = year_start[(years % maj_anndef == 0)]
        info_maj[major_idx] = True
        info['min'][year_start[(years % min_anndef == 0)]] = True

        info_fmt[major_idx] = '%Y'

    return info


def _quarterly_finder(vmin, vmax, freq):
    periodsperyear = 4
    vmin_orig = vmin
    (vmin, vmax) = (int(vmin), int(vmax))
    span = vmax - vmin + 1

    info = np.zeros(span,
                    dtype=[('val', int), ('maj', bool), ('min', bool),
                           ('fmt', '|S8')])
    info['val'] = np.arange(vmin, vmax + 1)
    info['fmt'] = ''
    dates_ = info['val']
    info_maj = info['maj']
    info_fmt = info['fmt']
    year_start = (dates_ % 4 == 0).nonzero()[0]

    if span <= 3.5 * periodsperyear:
        info_maj[year_start] = True
        info['min'] = True

        info_fmt[:] = 'Q%q'
        info_fmt[year_start] = 'Q%q\n%F'
        if not has_level_label(year_start, vmin_orig):
            if dates_.size > 1:
                idx = 1
            else:
                idx = 0
            info_fmt[idx] = 'Q%q\n%F'

    elif span <= 11 * periodsperyear:
        info_maj[year_start] = True
        info['min'] = True
        info_fmt[year_start] = '%F'

    else:
        years = dates_[year_start] // 4 + 1
        nyears = span / periodsperyear
        (min_anndef, maj_anndef) = _get_default_annual_spacing(nyears)
        major_idx = year_start[(years % maj_anndef == 0)]
        info_maj[major_idx] = True
        info['min'][year_start[(years % min_anndef == 0)]] = True
        info_fmt[major_idx] = '%F'

    return info


def _annual_finder(vmin, vmax, freq):
    (vmin, vmax) = (int(vmin), int(vmax + 1))
    span = vmax - vmin + 1

    info = np.zeros(span,
                    dtype=[('val', int), ('maj', bool), ('min', bool),
                           ('fmt', '|S8')])
    info['val'] = np.arange(vmin, vmax + 1)
    info['fmt'] = ''
    dates_ = info['val']

    (min_anndef, maj_anndef) = _get_default_annual_spacing(span)
    major_idx = dates_ % maj_anndef == 0
    info['maj'][major_idx] = True
    info['min'][(dates_ % min_anndef == 0)] = True
    info['fmt'][major_idx] = '%Y'

    return info


def get_finder(freq):
    if isinstance(freq, compat.string_types):
        freq = frequencies.get_freq(freq)
    fgroup = frequencies.get_freq_group(freq)

    if fgroup == FreqGroup.FR_ANN:
        return _annual_finder
    elif fgroup == FreqGroup.FR_QTR:
        return _quarterly_finder
    elif freq == FreqGroup.FR_MTH:
        return _monthly_finder
    elif ((freq >= FreqGroup.FR_BUS) or fgroup == FreqGroup.FR_WK):
        return _daily_finder
    else:  # pragma: no cover
        errmsg = "Unsupported frequency: %s" % (freq)
        raise NotImplementedError(errmsg)


class TimeSeries_DateLocator(Locator):
    """
    Locates the ticks along an axis controlled by a :class:`Series`.

    Parameters
    ----------
    freq : {var}
        Valid frequency specifier.
    minor_locator : {False, True}, optional
        Whether the locator is for minor ticks (True) or not.
    dynamic_mode : {True, False}, optional
        Whether the locator should work in dynamic mode.
    base : {int}, optional
    quarter : {int}, optional
    month : {int}, optional
    day : {int}, optional
    """

    def __init__(self, freq, minor_locator=False, dynamic_mode=True,
                 base=1, quarter=1, month=1, day=1, plot_obj=None):
        if isinstance(freq, compat.string_types):
            freq = frequencies.get_freq(freq)
        self.freq = freq
        self.base = base
        (self.quarter, self.month, self.day) = (quarter, month, day)
        self.isminor = minor_locator
        self.isdynamic = dynamic_mode
        self.offset = 0
        self.plot_obj = plot_obj
        self.finder = get_finder(freq)

    def _get_default_locs(self, vmin, vmax):
        "Returns the default locations of ticks."

        if self.plot_obj.date_axis_info is None:
            self.plot_obj.date_axis_info = self.finder(vmin, vmax, self.freq)

        locator = self.plot_obj.date_axis_info

        if self.isminor:
            return np.compress(locator['min'], locator['val'])
        return np.compress(locator['maj'], locator['val'])

    def __call__(self):
        'Return the locations of the ticks.'
        # axis calls Locator.set_axis inside set_m<xxxx>_formatter
        _check_implicitly_registered()

        vi = tuple(self.axis.get_view_interval())
        if vi != self.plot_obj.view_interval:
            self.plot_obj.date_axis_info = None
        self.plot_obj.view_interval = vi
        vmin, vmax = vi
        if vmax < vmin:
            vmin, vmax = vmax, vmin
        if self.isdynamic:
            locs = self._get_default_locs(vmin, vmax)
        else:  # pragma: no cover
            base = self.base
            (d, m) = divmod(vmin, base)
            vmin = (d + 1) * base
            locs = lrange(vmin, vmax + 1, base)
        return locs

    def autoscale(self):
        """
        Sets the view limits to the nearest multiples of base that contain the
        data.
        """
        # requires matplotlib >= 0.98.0
        (vmin, vmax) = self.axis.get_data_interval()

        locs = self._get_default_locs(vmin, vmax)
        (vmin, vmax) = locs[[0, -1]]
        if vmin == vmax:
            vmin -= 1
            vmax += 1
        return nonsingular(vmin, vmax)

# -------------------------------------------------------------------------
# --- Formatter ---
# -------------------------------------------------------------------------


class TimeSeries_DateFormatter(Formatter):
    """
    Formats the ticks along an axis controlled by a :class:`PeriodIndex`.

    Parameters
    ----------
    freq : {int, string}
        Valid frequency specifier.
    minor_locator : {False, True}
        Whether the current formatter should apply to minor ticks (True) or
        major ticks (False).
    dynamic_mode : {True, False}
        Whether the formatter works in dynamic mode or not.
    """

    def __init__(self, freq, minor_locator=False, dynamic_mode=True,
                 plot_obj=None):
        if isinstance(freq, compat.string_types):
            freq = frequencies.get_freq(freq)
        self.format = None
        self.freq = freq
        self.locs = []
        self.formatdict = None
        self.isminor = minor_locator
        self.isdynamic = dynamic_mode
        self.offset = 0
        self.plot_obj = plot_obj
        self.finder = get_finder(freq)

    def _set_default_format(self, vmin, vmax):
        "Returns the default ticks spacing."

        if self.plot_obj.date_axis_info is None:
            self.plot_obj.date_axis_info = self.finder(vmin, vmax, self.freq)
        info = self.plot_obj.date_axis_info

        if self.isminor:
            format = np.compress(info['min'] & np.logical_not(info['maj']),
                                 info)
        else:
            format = np.compress(info['maj'], info)
        self.formatdict = dict([(x, f) for (x, _, _, f) in format])
        return self.formatdict

    def set_locs(self, locs):
        'Sets the locations of the ticks'
        # don't actually use the locs. This is just needed to work with
        # matplotlib. Force to use vmin, vmax
        _check_implicitly_registered()

        self.locs = locs

        (vmin, vmax) = vi = tuple(self.axis.get_view_interval())
        if vi != self.plot_obj.view_interval:
            self.plot_obj.date_axis_info = None
        self.plot_obj.view_interval = vi
        if vmax < vmin:
            (vmin, vmax) = (vmax, vmin)
        self._set_default_format(vmin, vmax)

    def __call__(self, x, pos=0):
        _check_implicitly_registered()

        if self.formatdict is None:
            return ''
        else:
            fmt = self.formatdict.pop(x, '')
            return Period(ordinal=int(x), freq=self.freq).strftime(fmt)


class TimeSeries_TimedeltaFormatter(Formatter):
    """
    Formats the ticks along an axis controlled by a :class:`TimedeltaIndex`.
    """

    @staticmethod
    def format_timedelta_ticks(x, pos, n_decimals):
        """
        Convert seconds to 'D days HH:MM:SS.F'
        """
        s, ns = divmod(x, 1e9)
        m, s = divmod(s, 60)
        h, m = divmod(m, 60)
        d, h = divmod(h, 24)
        decimals = int(ns * 10**(n_decimals - 9))
        s = r'{:02d}:{:02d}:{:02d}'.format(int(h), int(m), int(s))
        if n_decimals > 0:
            s += '.{{:0{:0d}d}}'.format(n_decimals).format(decimals)
        if d != 0:
            s = '{:d} days '.format(int(d)) + s
        return s

    def __call__(self, x, pos=0):
        _check_implicitly_registered()
        (vmin, vmax) = tuple(self.axis.get_view_interval())
        n_decimals = int(np.ceil(np.log10(100 * 1e9 / (vmax - vmin))))
        if n_decimals > 9:
            n_decimals = 9
        return self.format_timedelta_ticks(x, pos, n_decimals)