Source code for astropy.visualization.time

# -*- coding: utf-8 -*-
# Licensed under a 3-clause BSD style license - see LICENSE.rst

import numpy as np

from datetime import datetime

from astropy.time import Time
from astropy import units as u

__all__ = ['time_support']

__doctest_requires__ = {'time_support': ['matplotlib']}

UNSUPPORTED_FORMATS = ('datetime', 'datetime64')
YMDHMS_FORMATS = ('fits', 'iso', 'isot', 'yday')
STR_FORMATS = YMDHMS_FORMATS + ('byear_str', 'jyear_str')

[docs]def time_support(*, scale=None, format=None, simplify=True): """ Enable support for plotting `astropy.time.Time` instances in matplotlib. May be (optionally) used with a ``with`` statement. >>> import matplotlib.pyplot as plt >>> from astropy import units as u >>> from astropy import visualization >>> with visualization.time_support(): # doctest: +IGNORE_OUTPUT ... plt.figure() ... plt.plot(Time(['2016-03-22T12:30:31', '2016-03-22T12:30:38', '2016-03-22T12:34:40'])) ... plt.draw() Parameters ---------- scale : str, optional The time scale to use for the times on the axis. If not specified, the scale of the first Time object passed to Matplotlib is used. format : str, optional The time format to use for the times on the axis. If not specified, the format of the first Time object passed to Matplotlib is used. simplify : bool, optional If possible, simplify labels, e.g. by removing 00:00:00.000 times from ISO strings if all labels fall on that time. """ import matplotlib.units as units from matplotlib.ticker import MaxNLocator, ScalarFormatter from astropy.visualization.wcsaxes.utils import select_step_hour, select_step_scalar class AstropyTimeLocator(MaxNLocator): # Note: we default to AutoLocator since many time formats # can just use this. def __init__(self, converter, *args, **kwargs): kwargs['nbins'] = 4 super().__init__(*args, **kwargs) self._converter = converter def tick_values(self, vmin, vmax): # Where we put the ticks depends on the format we are using if self._converter.format in YMDHMS_FORMATS: # If we are here, we need to check what the range of values # is and decide how to find tick locations accordingly vrange = vmax - vmin if (self._converter.format != 'yday' and vrange > 31) or vrange > 366: # greater than a month # We need to be careful here since not all years and months have # the same length # Start off by converting the values from the range to # datetime objects, so that we can easily extract the year and # month. tmin = Time(vmin, scale=self._converter.scale, format='mjd').datetime tmax = Time(vmax, scale=self._converter.scale, format='mjd').datetime # Find the range of years ymin = tmin.year ymax = tmax.year if ymax > ymin + 1: # greater than a year # Find the step we want to use ystep = int(select_step_scalar(max(1, (ymax - ymin) / 3))) ymin = ystep * (ymin // ystep) # Generate the years for these steps times = [] for year in range(ymin, ymax + 1, ystep): times.append(datetime(year=year, month=1, day=1)) else: # greater than a month but less than a year mmin = tmin.month mmax = tmax.month + 12 * (ymax - ymin) mstep = int(select_step_scalar(max(1, (mmax - mmin) / 3))) mmin = mstep * max(1, mmin // mstep) # Generate the months for these steps times = [] for month in range(mmin, mmax + 1, mstep): times.append(datetime(year=ymin + (month - 1) // 12, month=(month - 1) % 12 + 1, day=1)) # Convert back to MJD values = Time(times, scale=self._converter.scale).mjd elif vrange > 1: # greater than a day self.set_params(steps=[1, 2, 5, 10]) values = super().tick_values(vmin, vmax) else: # Determine ideal step dv = (vmax - vmin) / 3 * 24 << u.hourangle # And round to nearest sensible value dv = select_step_hour(dv).to_value(u.hourangle) / 24 # Determine tick locations imin = np.ceil(vmin / dv) imax = np.floor(vmax / dv) values = np.arange(imin, imax + 1, dtype=np.int64) * dv else: values = super().tick_values(vmin, vmax) # Get rid of values outside of the input interval values = values[(values >= vmin) & (values <= vmax)] return values def __call__(self): vmin, vmax = self.axis.get_view_interval() return self.tick_values(vmin, vmax) class AstropyTimeFormatter(ScalarFormatter): def __init__(self, converter, *args, **kwargs): super().__init__(*args, **kwargs) self._converter = converter self.set_useOffset(False) self.set_scientific(False) def __call__(self, value, pos=None): # Needed for Matplotlib <3.1 if self._converter.format in STR_FORMATS: return self.format_ticks([value])[0] else: return super().__call__(value, pos=pos) def format_ticks(self, values): if len(values) == 0: return [] if self._converter.format in YMDHMS_FORMATS: times = Time(values, format='mjd', scale=self._converter.scale) formatted = getattr(times, self._converter.format) if self._converter.simplify: if self._converter.format in ('fits', 'iso', 'isot'): if all([x.endswith('00:00:00.000') for x in formatted]): split = ' ' if self._converter.format == 'iso' else 'T' formatted = [x.split(split)[0] for x in formatted] elif self._converter.format == 'yday': if all([x.endswith(':001:00:00:00.000') for x in formatted]): formatted = [x.split(':', 1)[0] for x in formatted] return formatted elif self._converter.format == 'byear_str': return Time(values, format='byear', scale=self._converter.scale).byear_str elif self._converter.format == 'jyear_str': return Time(values, format='jyear', scale=self._converter.scale).jyear_str else: return super().format_ticks(values) class MplTimeConverter(units.ConversionInterface): def __init__(self, scale=None, format=None, simplify=None): super().__init__() self.format = format self.scale = scale self.simplify = simplify # Keep track of original converter in case the context manager is # used in a nested way. self._original_converter = units.registry.get(Time) units.registry[Time] = self @property def format(self): return self._format @format.setter def format(self, value): if value in UNSUPPORTED_FORMATS: raise ValueError(f'time_support does not support format={value}') self._format = value def __enter__(self): return self def __exit__(self, type, value, tb): if self._original_converter is None: del units.registry[Time] else: units.registry[Time] = self._original_converter def default_units(self, x, axis): if isinstance(x, tuple): x = x[0] if self.format is None: self.format = x.format if self.scale is None: self.scale = x.scale return 'astropy_time' def convert(self, value, unit, axis): """ Convert a Time value to a scalar or array. """ scaled = getattr(value, self.scale) if self.format in YMDHMS_FORMATS: return scaled.mjd elif self.format == 'byear_str': return scaled.byear elif self.format == 'jyear_str': return scaled.jyear else: return getattr(scaled, self.format) def axisinfo(self, unit, axis): """ Return major and minor tick locators and formatters. """ majloc = AstropyTimeLocator(self) majfmt = AstropyTimeFormatter(self) return units.AxisInfo(majfmt=majfmt, majloc=majloc, label=f'Time ({self.scale})') return MplTimeConverter(scale=scale, format=format, simplify=simplify)