# Licensed under a 3-clause BSD style license - see LICENSE.rst """ The astropy.time package provides functionality for manipulating times and dates. Specific emphasis is placed on supporting time scales (e.g. UTC, TAI, UT1) and time representations (e.g. JD, MJD, ISO 8601) that are used in astronomy. """ from __future__ import (absolute_import, division, print_function, unicode_literals) import fnmatch import itertools import time from datetime import datetime import numpy as np import functools from .. import units as u from ..utils import deprecated, deprecated_attribute from ..utils.exceptions import AstropyBackwardsIncompatibleChangeWarning from ..utils.compat.misc import override__dir__ from ..extern import six __all__ = ['Time', 'TimeDelta', 'TimeFormat', 'TimeJD', 'TimeMJD', 'TimeFromEpoch', 'TimeUnix', 'TimeCxcSec', 'TimeGPS', 'TimePlotDate', 'TimeDatetime', 'TimeString', 'TimeISO', 'TimeISOT', 'TimeYearDayTime', 'TimeEpochDate', 'TimeBesselianEpoch', 'TimeJulianEpoch', 'TimeDeltaFormat', 'TimeDeltaSec', 'TimeDeltaJD', 'ScaleValueError', 'OperandTypeError', 'TimeEpochDateString', 'TimeBesselianEpochString', 'TimeJulianEpochString', 'TIME_FORMATS', 'TIME_DELTA_FORMATS', 'TIME_SCALES', 'TIME_DELTA_SCALES'] __doctest_skip__ = ['TimePlotDate'] try: # Not guaranteed available at setup time from . import erfa_time except ImportError: if not _ASTROPY_SETUP_: raise MJD_ZERO = 2400000.5 SECS_PER_DAY = 86400 # These both get filled in at end after TimeFormat subclasses defined TIME_FORMATS = {} TIME_DELTA_FORMATS = {} TIME_SCALES = ('tai', 'tcb', 'tcg', 'tdb', 'tt', 'ut1', 'utc') MULTI_HOPS = {('tai', 'tcb'): ('tt', 'tdb'), ('tai', 'tcg'): ('tt',), ('tai', 'ut1'): ('utc',), ('tai', 'tdb'): ('tt',), ('tcb', 'tcg'): ('tdb', 'tt'), ('tcb', 'tt'): ('tdb',), ('tcb', 'ut1'): ('tdb', 'tt', 'tai', 'utc'), ('tcb', 'utc'): ('tdb', 'tt', 'tai'), ('tcg', 'tdb'): ('tt',), ('tcg', 'ut1'): ('tt', 'tai', 'utc'), ('tcg', 'utc'): ('tt', 'tai'), ('tdb', 'ut1'): ('tt', 'tai', 'utc'), ('tdb', 'utc'): ('tt', 'tai'), ('tt', 'ut1'): ('tai', 'utc'), ('tt', 'utc'): ('tai',), } GEOCENTRIC_SCALES = ('tai', 'tt', 'tcg') BARYCENTRIC_SCALES = ('tcb', 'tdb') ROTATIONAL_SCALES = ('ut1',) TIME_DELTA_TYPES = dict((scale, scales) for scales in (GEOCENTRIC_SCALES, BARYCENTRIC_SCALES, ROTATIONAL_SCALES) for scale in scales) TIME_DELTA_SCALES = TIME_DELTA_TYPES.keys() # TODO: access these from erfa.h?? # L_G = 1 - d(TT)/d(TCG) -> d(TT)/d(TCG) = 1-L_G # d(TCG)/d(TT) = 1/(1-L_G) = 1 + (1-(1-L_G))/(1-L_G) = 1 + L_G/(1-L_G) ERFA_ELG = 6.969290134e-10 # L_B = 1 - d(TDB)/d(TCB) ERFA_ELB = 1.550519768e-8 # scale offsets as second = first + first * scale_offset[(first,second)] SCALE_OFFSETS = {('tt', 'tai'): None, ('tai', 'tt'): None, ('tcg', 'tt'): -ERFA_ELG, ('tt', 'tcg'): ERFA_ELG / (1. - ERFA_ELG), ('tcg', 'tai'): -ERFA_ELG, ('tai', 'tcg'): ERFA_ELG / (1. - ERFA_ELG), ('tcb', 'tdb'): -ERFA_ELB, ('tdb', 'tcb'): ERFA_ELB / (1. - ERFA_ELB)} # triple-level dictionary, yay! SIDEREAL_TIME_MODELS = { 'mean': { 'IAU2006': {'function': erfa_time.gmst06, 'scales': ('ut1', 'tt')}, 'IAU2000': {'function': erfa_time.gmst00, 'scales': ('ut1', 'tt')}, 'IAU1982': {'function': erfa_time.gmst82, 'scales': ('ut1',)}}, 'apparent': { 'IAU2006A': {'function': erfa_time.gst06a, 'scales': ('ut1', 'tt')}, 'IAU2000A': {'function': erfa_time.gst00a, 'scales': ('ut1', 'tt')}, 'IAU2000B': {'function': erfa_time.gst00b, 'scales': ('ut1',)}, 'IAU1994': {'function': erfa_time.gst94, 'scales': ('ut1',)}}} # TODO: remove in version beyond 0.4 # with longitude and latitude swapped to get them in the right order, # insist that these are given as keyword arguments def kwargs_after_scale(func): @functools.wraps(func) def new_func(*args, **kwargs): if len(args) > 5: AstropyBackwardsIncompatibleChangeWarning( 'lon and lat have been replaced with location in version 0.4. ' 'Code should be changed to set the location explicitly using ' 'a keyword argument: location=EarthLocation(...), or via a ' 'shortcut with a tuple: location=(lon, lat, [height]) or ' 'location=(x, y, z)') return func(*args, **kwargs) return new_func class Time(object): """ Represent and manipulate times and dates for astronomy. A `Time` object is initialized with one or more times in the ``val`` argument. The input times in ``val`` must conform to the specified ``format`` and must correspond to the specified time ``scale``. The optional ``val2`` time input should be supplied only for numeric input formats (e.g. JD) where very high precision (better than 64-bit precision) is required. Parameters ---------- val : sequence, str, number, or `~astropy.time.Time` object Value(s) to initialize the time or times. val2 : sequence, str, or number; optional Value(s) to initialize the time or times. format : str, optional Format of input value(s) scale : str, optional Time scale of input value(s) precision : int, optional Digits of precision in string representation of time in_subfmt : str, optional Subformat for inputting string times out_subfmt : str, optional Subformat for outputting string times location : `~astropy.coordinates.EarthLocation` or tuple, optional If given as an tuple, it should be able to initialize an an EarthLocation instance, i.e., either contain 3 items with units of length for geocentric coordinates, or contain a longitude, latitude, and an optional height for geodetic coordinates. Can be a single location, or one for each input time. copy : bool, optional Make a copy of the input values """ is_scalar = deprecated_attribute(name='is_scalar', since='0.3', alternative='isscalar') _precision = 3 # Precision when for seconds as floating point _in_subfmt = '*' # Select subformat for inputting string times _out_subfmt = '*' # Select subformat for outputting string times SCALES = TIME_SCALES """List of time scales""" FORMATS = TIME_FORMATS """Dict of time formats""" # Make sure that reverse arithmetic (e.g., TimeDelta.__rmul__) # gets called over the __mul__ of Numpy arrays. __array_priority__ = 20000 @kwargs_after_scale def __new__(cls, val, val2=None, format=None, scale=None, precision=None, in_subfmt=None, out_subfmt=None, location=None, copy=False, **kwargs): if isinstance(val, cls): self = val.replicate(format=format, copy=copy) else: self = super(Time, cls).__new__(cls) return self def __getnewargs__(self): return (self._time,) @kwargs_after_scale def __init__(self, val, val2=None, format=None, scale=None, precision=None, in_subfmt=None, out_subfmt=None, location=None, copy=False, **kwargs): if 'lon' in kwargs or 'lat' in kwargs: AstropyBackwardsIncompatibleChangeWarning( 'lon and lat have been replaced with location in version 0.4. ' 'Code should be changed to set the location explicitly using ' 'a keyword argument: location=(lon, lat, [height]) or ' 'location=(x, y, z)') if location is None: location = (kwargs.pop('lon', None), kwargs.pop('lat', None)) if location is not None: from ..coordinates import EarthLocation if isinstance(location, EarthLocation): self.location = location else: self.location = EarthLocation(*location) else: self.location = None if precision is not None: self.precision = precision if in_subfmt is not None: self.in_subfmt = in_subfmt if out_subfmt is not None: self.out_subfmt = out_subfmt if isinstance(val, self.__class__): if scale is not None: self._set_scale(scale) else: self._init_from_vals(val, val2, format, scale, copy) if (self.location is not None and self.location.shape and len(self.location) != (1 if self.isscalar else len(self))): raise ValueError('Have {0} times but {1} locations. Should ' 'either give a single location or one for each ' 'time'.format(1 if self.isscalar else len(self), len(self.location))) def _init_from_vals(self, val, val2, format, scale, copy): """ Set the internal _format, scale, and _time attrs from user inputs. This handles coercion into the correct shapes and some basic input validation. """ # check whether input is some form of list of Time objects, # since these should be treated separately try: val0 = val[0] except: isiterable_of_times = False else: isiterable_of_times = isinstance(val0, self.__class__) if isiterable_of_times: if val2 is not None: raise ValueError( 'non-None second value for list of {0!r} objects' .format(self.__class__.__name__)) self.isscalar = False else: # Coerce val into a 1-d array val, val_ndim = _make_1d_array(val, copy) self.isscalar = (val_ndim == 0) # If val2 is not None, ensure consistency if val2 is not None: val2, val2_ndim = _make_1d_array(val2, copy) if val_ndim != val2_ndim: raise ValueError('Input val and val2 must have same ' 'dimensions') if len(val) != len(val2): raise ValueError('Input val and val2 must match in length') if scale is not None: if not (isinstance(scale, six.string_types) and scale.lower() in self.SCALES): raise ScaleValueError("Scale {0} is not in the allowed scales " "{1}".format(repr(scale), sorted(self.SCALES))) # Parse / convert input values into internal jd1, jd2 based on format self._time = self._get_time_fmt(val, val2, format, scale) self._format = self._time.name def _get_time_fmt(self, val, val2, format, scale): """ Given the supplied val, val2, format and scale try to instantiate the corresponding TimeFormat class to convert the input values into the internal jd1 and jd2. If format is `None` and the input is a string-type or object array then guess available formats and stop when one matches. """ if format is None and (isinstance(val[0], self.__class__) or val.dtype.kind in ('S', 'U', 'O')): formats = [(name, cls) for name, cls in self.FORMATS.items() if issubclass(cls, TimeUnique)] err_msg = ('any of the formats where the format keyword is ' 'optional {0}'.format([name for name, cls in formats])) elif not (isinstance(format, six.string_types) and format.lower() in self.FORMATS): if format is None: raise ValueError("No time format was given, and the input is " "not unique") else: raise ValueError("Format {0} is not one of the allowed " "formats {1}".format(repr(format), sorted(self.FORMATS))) else: formats = [(format, self.FORMATS[format])] err_msg = 'the format class {0}'.format(format) for format, FormatClass in formats: try: return FormatClass(val, val2, scale, self.precision, self.in_subfmt, self.out_subfmt) except (ValueError, TypeError): pass else: raise ValueError('Input values did not match {0}'.format(err_msg)) @classmethod def now(cls): """ Creates a new object corresponding to the instant in time this method is called. .. note:: "Now" is determined using the `~datetime.datetime.utcnow` function, so its accuracy and precision is determined by that function. Generally that means it is set by the accuracy of your system clock. Returns ------- nowtime A new `Time` object (or a subclass of `Time` if this is called from such a subclass) at the current time. """ # call `utcnow` immediately to be sure it's ASAP dtnow = datetime.utcnow() return cls(val=dtnow, format='datetime', scale='utc') @property def format(self): """Time format""" return self._format def __repr__(self): return ("<{0} object: scale='{1}' format='{2}' value={3}>" .format(self.__class__.__name__, self.scale, self.format, getattr(self, self.format))) def __str__(self): return str(getattr(self, self.format)) @property def scale(self): """Time scale""" return self._time.scale def _set_scale(self, scale): """ This is the key routine that actually does time scale conversions. This is not public and not connected to the read-only scale property. """ if scale == self.scale: return if scale not in self.SCALES: raise ValueError("Scale {0} is not in the allowed scales {1}" .format(repr(scale), sorted(self.SCALES))) # Determine the chain of scale transformations to get from the current # scale to the new scale. MULTI_HOPS contains a dict of all # transformations (xforms) that require intermediate xforms. # The MULTI_HOPS dict is keyed by (sys1, sys2) in alphabetical order. xform = (self.scale, scale) xform_sort = tuple(sorted(xform)) multi = MULTI_HOPS.get(xform_sort, ()) xforms = xform_sort[:1] + multi + xform_sort[-1:] # If we made the reverse xform then reverse it now. if xform_sort != xform: xforms = tuple(reversed(xforms)) # Transform the jd1,2 pairs through the chain of scale xforms. jd1, jd2 = self._time.jd1, self._time.jd2 for sys1, sys2 in six.moves.zip(xforms[:-1], xforms[1:]): # Some xforms require an additional delta_ argument that is # provided through Time methods. These values may be supplied by # the user or computed based on available approximations. The # get_delta_ methods are available for only one combination of # sys1, sys2 though the property applies for both xform directions. args = [jd1, jd2] for sys12 in ((sys1, sys2), (sys2, sys1)): dt_method = '_get_delta_{0}_{1}'.format(*sys12) try: get_dt = getattr(self, dt_method) except AttributeError: pass else: args.append(get_dt(jd1, jd2)) break conv_func = getattr(erfa_time, sys1 + '_' + sys2) jd1, jd2 = conv_func(*args) self._time = self.FORMATS[self.format](jd1, jd2, scale, self.precision, self.in_subfmt, self.out_subfmt, from_jd=True) @property def precision(self): """ Decimal precision when outputting seconds as floating point (int value between 0 and 9 inclusive). """ return self._precision @precision.setter def precision(self, val): if not isinstance(val, int) or val < 0 or val > 9: raise ValueError('precision attribute must be an int between ' '0 and 9') self._precision = val @property def in_subfmt(self): """ Unix wildcard pattern to select subformats for parsing string input times. """ return self._in_subfmt @in_subfmt.setter def in_subfmt(self, val): if not isinstance(val, six.string_types): raise ValueError('in_subfmt attribute must be a string') self._in_subfmt = val @property def out_subfmt(self): """ Unix wildcard pattern to select subformats for outputting times. """ return self._out_subfmt @out_subfmt.setter def out_subfmt(self, val): if not isinstance(val, six.string_types): raise ValueError('out_subfmt attribute must be a string') self._out_subfmt = val def _shaped_like_input(self, values): if self.isscalar: value0 = values[0] try: return value0.tolist() except AttributeError: return value0 else: return values @property def jd1(self): """ First of the two doubles that internally store time value(s) in JD. """ return self._shaped_like_input(self._time.jd1) @property def jd2(self): """ Second of the two doubles that internally store time value(s) in JD. """ return self._shaped_like_input(self._time.jd2) @property def value(self): """Time value(s) in current format""" return self._shaped_like_input(self._time.value) @property @deprecated("0.3", name="val", alternative="value") def val(self): return self.value @property @deprecated("0.3", name="vals", alternative="value") def vals(self): """Time values in current format as a numpy array.""" return self.value @property @deprecated("0.4", name="lon", alternative="location.longitude") def lon(self): return self.location.longitude @property @deprecated("0.4", name="lat", alternative="location.latitude") def lat(self): return self.location.latitude def sidereal_time(self, kind, longitude=None, model=None): """Calculate sidereal time. Parameters --------------- kind : str ``'mean'`` or ``'apparent'``, i.e., accounting for precession only, or also for nutation. longitude : `~astropy.units.Quantity`, `str`, or `None`; optional The longitude on the Earth at which to compute the sidereal time. Can be given as a `~astropy.units.Quantity` with angular units (or an `~astropy.coordinates.Angle` or `~astropy.coordinates.Longitude`), or as a name of an observatory (currently, only ``'greenwich'`` is supported, equivalent to 0 deg). If `None` (default), the ``lon`` attribute of the Time object is used. model : str or `None`; optional Precession (and nutation) model to use. The available ones are: - {0}: {1} - {2}: {3} If `None` (default), the last (most recent) one from the appropriate list above is used. Returns ------- sidereal time : `~astropy.coordinates.Longitude` Sidereal time as a quantity with units of hourangle """ # docstring is formatted below from ..coordinates import Longitude if kind.lower() not in SIDEREAL_TIME_MODELS.keys(): raise ValueError('The kind of sidereal time has to be {0}'.format( ' or '.join(sorted(SIDEREAL_TIME_MODELS.keys())))) available_models = SIDEREAL_TIME_MODELS[kind.lower()] if model is None: model = sorted(available_models.keys())[-1] else: if model.upper() not in available_models: raise ValueError( 'Model {0} not implemented for {1} sidereal time; ' 'available models are {2}' .format(model, kind, sorted(available_models.keys()))) if longitude is None: if self.location is None: raise ValueError('No longitude is given but the location for ' 'the Time object is not set.') longitude = self.location.longitude elif longitude == 'greenwich': longitude = Longitude(0., u.degree, wrap_angle=180.*u.degree) else: # sanity check on input longitude = Longitude(longitude, u.degree, wrap_angle=180.*u.degree) gst = self._erfa_sidereal_time(available_models[model.upper()]) return Longitude(gst + longitude, u.hourangle) sidereal_time.__doc__ = sidereal_time.__doc__.format( 'apparent', sorted(SIDEREAL_TIME_MODELS['apparent'].keys()), 'mean', sorted(SIDEREAL_TIME_MODELS['mean'].keys())) def _erfa_sidereal_time(self, model): """Caculate a sidereal time using a IAU precession/nutation model.""" from ..coordinates import Longitude erfa_function = model['function'] erfa_parameters = [getattr(getattr(self, scale)._time, jd_part) for scale in model['scales'] for jd_part in ('jd1', 'jd2')] sidereal_time = erfa_function(*erfa_parameters) return Longitude(self._shaped_like_input(sidereal_time), u.radian).to(u.hourangle) def copy(self, format=None): """ Return a fully independent copy the Time object, optionally changing the format. If ``format`` is supplied then the time format of the returned Time object will be set accordingly, otherwise it will be unchanged from the original. In this method a full copy of the internal time arrays will be made. The internal time arrays are normally not changeable by the user so in most cases the ``replicate()`` method should be used. Parameters ---------- format : str, optional Time format of the copy. Returns ------- tm: Time object Copy of this object """ return self.replicate(format, copy=True) def replicate(self, format=None, copy=False): """ Return a replica of the Time object, optionally changing the format. If ``format`` is supplied then the time format of the returned Time object will be set accordingly, otherwise it will be unchanged from the original. If ``copy`` is set to `True` then a full copy of the internal time arrays will be made. By default the replica will use a reference to the original arrays when possible to save memory. The internal time arrays are normally not changeable by the user so in most cases it should not be necessary to set ``copy`` to `True`. The convenience method copy() is available in which ``copy`` is `True` by default. Parameters ---------- format : str, optional Time format of the replica. copy : bool, optional Return a true copy instead of using references where possible. Returns ------- tm: Time object Replica of this object """ # To avoid recalculating integer day + fraction, no longer just # instantiate a new class instance, but rather do the steps by hand. # This also avoids quite a bit of unnecessary work in __init__ ### tm = self.__class__(self._time.jd1, self._time.jd2, ### format='jd', scale=self.scale, copy=copy) tm = super(Time, self.__class__).__new__(self.__class__) tm._time = TimeJD(self._time.jd1.copy() if copy else self._time.jd1, self._time.jd2.copy() if copy else self._time.jd2, self.scale, self.precision, self.in_subfmt, self.out_subfmt, from_jd=True) # Optional or non-arg attributes attrs = ('isscalar', '_delta_ut1_utc', '_delta_tdb_tt', 'location', 'precision', 'in_subfmt', 'out_subfmt') for attr in attrs: try: val = getattr(self, attr) except AttributeError: continue if copy and hasattr(val, 'copy'): val = val.copy() setattr(tm, attr, val) if format is None: format = self.format # Make the new internal _time object corresponding to the format # in the copy. If the format is unchanged this process is lightweight # and does not create any new arrays. NewFormat = tm.FORMATS[format] # If the new format class has a "scale" class attr then that scale is # required and the input jd1,2 has to be converted first. if hasattr(NewFormat, 'required_scale'): scale = NewFormat.required_scale new = getattr(tm, scale) # self JDs converted to scale tm._time = NewFormat(new._time.jd1, new._time.jd2, scale, tm.precision, tm.in_subfmt, tm.out_subfmt, from_jd=True) else: tm._time = NewFormat(tm._time.jd1, tm._time.jd2, tm._time._scale, tm.precision, tm.in_subfmt, tm.out_subfmt, from_jd=True) tm._format = format return tm def __copy__(self): """ Overrides the default behavior of the `copy.copy` function in the python stdlib to behave like `Time.copy`. Does *not* make a copy of the JD arrays - only copies by reference. """ return self.replicate() def __deepcopy__(self, memo): """ Overrides the default behavior of the `copy.deepcopy` function in the python stdlib to behave like `Time.copy`. Does make a copy of the JD arrays. """ return self.copy() def __getitem__(self, item): if self.isscalar: raise TypeError('scalar {0!r} object is not subscriptable.'.format( self.__class__.__name__)) tm = self.replicate() jd1 = self._time.jd1[item] tm.isscalar = jd1.ndim == 0 def keepasarray(x): return np.atleast_1d(x) if isinstance(x, np.float) else x tm._time.jd1 = keepasarray(jd1) tm._time.jd2 = keepasarray(self._time.jd2[item]) attrs = ('_delta_ut1_utc', '_delta_tdb_tt', 'location') for attr in attrs: val = getattr(self, attr, None) if val is not None: try: setattr(tm, attr, keepasarray(val[item])) except IndexError: # location may be scalar (same for all) continue return tm def __getattr__(self, attr): """ Get dynamic attributes to output format or do timescale conversion. """ if attr in self.SCALES and self.scale is not None: tm = self.replicate() tm._set_scale(attr) return tm elif attr in self.FORMATS: tm = self.replicate(format=attr) if hasattr(self.FORMATS[attr], 'epoch_scale'): tm._set_scale(self.FORMATS[attr].epoch_scale) if self.isscalar: out = tm._time.value[0] # convert to native python for non-object dtypes if tm._time.value.dtype.kind != 'O': out = out.tolist() else: out = tm.value return out elif attr in TIME_SCALES: # allowed ones done above (self.SCALES) if self.scale is None: raise ScaleValueError("Cannot convert TimeDelta with " "undefined scale to any defined scale.") else: raise ScaleValueError("Cannot convert {0} with scale " "'{1}' to scale '{2}'" .format(self.__class__.__name__, self.scale, attr)) else: # Should raise AttributeError return self.__getattribute__(attr) @override__dir__ def __dir__(self): result = set(self.SCALES) result.update(self.FORMATS) return result def _match_len(self, val): """ Ensure that `val` is matched to length of self. If val has length 1 then broadcast, otherwise cast to double and make sure length matches. """ val, ndim = _make_1d_array(val, copy=True) # be conservative and copy if len(val) == 1: oval = val val = np.empty(len(self._time), dtype=np.double) val[:] = oval elif len(val) != len(self._time): raise ValueError('Attribute length must match Time object length') return val def get_delta_ut1_utc(self, iers_table=None, return_status=False): """Find UT1 - UTC differences by interpolating in IERS Table. Parameters ---------- iers_table : ``astropy.utils.iers.IERS`` table, optional Table containing UT1-UTC differences from IERS Bulletins A and/or B. If `None`, use default version (see ``astropy.utils.iers``) return_status : bool Whether to return status values. If `False` (default), iers raises `~.exceptions.IndexError` if any time is out of the range covered by the IERS table. Returns ------- ut1_utc: float or float array UT1-UTC, interpolated in IERS Table status: int or int array Status values (if ``return_status=`True```):: ``astropy.utils.iers.FROM_IERS_B`` ``astropy.utils.iers.FROM_IERS_A`` ``astropy.utils.iers.FROM_IERS_A_PREDICTION`` ``astropy.utils.iers.TIME_BEFORE_IERS_RANGE`` ``astropy.utils.iers.TIME_BEYOND_IERS_RANGE`` Notes ----- In normal usage, UT1-UTC differences are calculated automatically on the first instance ut1 is needed. Examples -------- To check in code whether any times are before the IERS table range:: >>> from astropy.utils.iers import TIME_BEFORE_IERS_RANGE >>> t = Time(['1961-01-01', '2000-01-01'], scale='utc') >>> delta, status = t.get_delta_ut1_utc(return_status=True) >>> status == TIME_BEFORE_IERS_RANGE array([ True, False], dtype=bool) To use an updated IERS A bulletin to calculate UT1-UTC (see also ``astropy.utils.iers``):: >>> from astropy.utils.iers import IERS_A, IERS_A_URL >>> from astropy.utils.data import download_file >>> t = Time(['1974-01-01', '2000-01-01'], scale='utc') >>> iers_a_file = download_file(IERS_A_URL, ... cache=True) # doctest: +REMOTE_DATA Downloading ... [Done] >>> iers_a = IERS_A.open(iers_a_file) # doctest: +REMOTE_DATA >>> t.delta_ut1_utc = t.get_delta_ut1_utc(iers_a) # doctest: +REMOTE_DATA The delta_ut1_utc property will be used to calculate t.ut1; raises IndexError if any of the times is out of range. """ if iers_table is None: from ..utils.iers import IERS iers_table = IERS.open() return iers_table.ut1_utc(self.utc, return_status=return_status) # Property for ERFA DUT arg = UT1 - UTC def _get_delta_ut1_utc(self, jd1=None, jd2=None): """ Get ERFA DUT arg = UT1 - UTC. This getter takes optional jd1 and jd2 args because it gets called that way when converting time scales. If delta_ut1_utc is not yet set, this will interpolate them from the the IERS table. """ # Sec. 4.3.1: the arg DUT is the quantity delta_UT1 = UT1 - UTC in # seconds. It is obtained from tables published by the IERS. if not hasattr(self, '_delta_ut1_utc'): from ..utils.iers import IERS iers_table = IERS.open() # jd1, jd2 are normally set (see above), except if delta_ut1_utc # is access directly; ensure we behave as expected for that case if jd1 is None: self_utc = self.utc jd1, jd2 = self_utc.jd1, self_utc.jd2 scale = 'utc' else: scale = self.scale # interpolate UT1-UTC in IERS table delta = iers_table.ut1_utc(jd1, jd2) # if we interpolated using UT1 jds, we may be off by one # second near leap seconds (and very slightly off elsewhere) if scale == 'ut1': # calculate UTC using the offset we got; the ERFA routine # is tolerant of leap seconds, so will do this right jd1_utc, jd2_utc = erfa_time.ut1_utc(jd1, jd2, delta) # calculate a better estimate using the nearly correct UTC delta = iers_table.ut1_utc(jd1_utc, jd2_utc) self._set_delta_ut1_utc(delta) return self._delta_ut1_utc def _set_delta_ut1_utc(self, val): self._delta_ut1_utc = self._match_len(val) # Note can't use @property because _get_delta_tdb_tt is explicitly # called with the optional jd1 and jd2 args. delta_ut1_utc = property(_get_delta_ut1_utc, _set_delta_ut1_utc) """UT1 - UTC time scale offset""" # Property for ERFA DTR arg = TDB - TT def _get_delta_tdb_tt(self, jd1=None, jd2=None): if not hasattr(self, '_delta_tdb_tt'): # If jd1 and jd2 are not provided (which is the case for property # attribute access) then require that the time scale is TT or TDB. # Otherwise the computations here are not correct. if jd1 is None or jd2 is None: if self.scale not in ('tt', 'tdb'): raise ValueError('Accessing the delta_tdb_tt attribute ' 'is only possible for TT or TDB time ' 'scales') else: jd1 = self._time.jd1 jd2 = self._time.jd2 # First go from the current input time (which is either # TDB or TT) to an approximate UT1. Since TT and TDB are # pretty close (few msec?), assume TT. Similarly, since the # UT1 terms are very small, use UTC instead of UT1. njd1, njd2 = erfa_time.tt_tai(jd1, jd2) njd1, njd2 = erfa_time.tai_utc(njd1, njd2) # subtract 0.5, so UT is fraction of the day from midnight ut = day_frac(njd1 - 0.5, njd2)[1] if self.location is None: from ..coordinates import EarthLocation location = EarthLocation.from_geodetic(0., 0., 0.) else: location = self.location # Geodetic params needed for d_tdb_tt() lon = location.longitude rxy = np.hypot(location.x, location.y) z = location.z self._delta_tdb_tt = erfa_time.d_tdb_tt( jd1, jd2, ut, np.atleast_1d(lon.to(u.radian).value), np.atleast_1d(rxy.to(u.km).value), np.atleast_1d(z.to(u.km).value)) return self._delta_tdb_tt def _set_delta_tdb_tt(self, val): self._delta_tdb_tt = self._match_len(val) # Note can't use @property because _get_delta_tdb_tt is explicitly # called with the optional jd1 and jd2 args. delta_tdb_tt = property(_get_delta_tdb_tt, _set_delta_tdb_tt) """TDB - TT time scale offset""" def __len__(self): return len(self.jd1) def __sub__(self, other): if not isinstance(other, Time): try: other = TimeDelta(other) except: raise OperandTypeError(self, other, '-') # Tdelta - something is dealt with in TimeDelta, so we have # T - Tdelta = T # T - T = Tdelta other_is_delta = isinstance(other, TimeDelta) # we need a constant scale to calculate, which is guaranteed for # TimeDelta, but not for Time (which can be UTC) if other_is_delta: # T - Tdelta if self.scale in other.SCALES: out = self.replicate() if other.scale not in (out.scale, None): other = getattr(other, out.scale) else: out = getattr(self, (other.scale if other.scale is not None else 'tai')) # remove attributes that are invalidated by changing time for attr in ('_delta_ut1_utc', '_delta_tdb_tt'): if hasattr(out, attr): delattr(out, attr) else: # T - T self_time = (self._time if self.scale in TIME_DELTA_SCALES else self.tai._time) # set up TimeDelta, subtraction to be done shortly out = TimeDelta(self_time.jd1, self_time.jd2, format='jd', scale=self_time.scale) if other.scale != out.scale: other = getattr(other, out.scale) jd1 = out._time.jd1 - other._time.jd1 jd2 = out._time.jd2 - other._time.jd2 out._time.jd1, out._time.jd2 = day_frac(jd1, jd2) out.isscalar = self.isscalar and other.isscalar if other_is_delta and out.scale != self.scale: return getattr(out, self.scale) return out def __add__(self, other): if not isinstance(other, Time): try: other = TimeDelta(other) except: raise OperandTypeError(self, other, '+') # Tdelta + something is dealt with in TimeDelta, so we have # T + Tdelta = T # T + T = error if not isinstance(other, TimeDelta): raise OperandTypeError(self, other, '+') # ideally, we calculate in the scale of the Time item, since that is # what we want the output in, but this may not be possible, since # TimeDelta cannot be converted arbitrarily if self.scale in other.SCALES: out = self.replicate() if other.scale not in (out.scale, None): other = getattr(other, out.scale) else: out = getattr(self, (other.scale if other.scale is not None else 'tai')) # remove attributes that are invalidated by changing time for attr in ('_delta_ut1_utc', '_delta_tdb_tt'): if hasattr(out, attr): delattr(out, attr) jd1 = out._time.jd1 + other._time.jd1 jd2 = out._time.jd2 + other._time.jd2 out._time.jd1, out._time.jd2 = day_frac(jd1, jd2) out.isscalar = self.isscalar and other.isscalar if out.scale != self.scale: return getattr(out, self.scale) return out def __radd__(self, other): return self.__add__(other) def __rsub__(self, other): out = self.__sub__(other) return -out def _time_difference(self, other, op=None): """If other is of same class as self, return difference in self.scale. Otherwise, raise OperandTypeError. """ if other.__class__ is not self.__class__: try: other = self.__class__(other, scale=self.scale) except: raise OperandTypeError(self, other, op) if(self.scale is not None and self.scale not in other.SCALES or other.scale is not None and other.scale not in self.SCALES): raise TypeError("Cannot compare TimeDelta instances with scales " "'{0}' and '{1}'".format(self.scale, other.scale)) if self.scale is not None and other.scale is not None: other = getattr(other, self.scale) return (self.jd1 - other.jd1) + (self.jd2 - other.jd2) def __lt__(self, other): return self._time_difference(other, '<') < 0. def __le__(self, other): return self._time_difference(other, '<=') <= 0. def __eq__(self, other): """ If other is an incompatible object for comparison, return `False`. Otherwise, return `True` if the time difference between self and other is zero. """ try: diff = self._time_difference(other) except OperandTypeError: return False return diff == 0. def __ne__(self, other): """ If other is an incompatible object for comparison, return `True`. Otherwise, return `False` if the time difference between self and other is zero. """ try: diff = self._time_difference(other) except OperandTypeError: return True return diff != 0. def __gt__(self, other): return self._time_difference(other, '>') > 0. def __ge__(self, other): return self._time_difference(other, '>=') >= 0. class TimeDelta(Time): """ Represent the time difference between two times. A TimeDelta object is initialized with one or more times in the ``val`` argument. The input times in ``val`` must conform to the specified ``format``. The optional ``val2`` time input should be supplied only for numeric input formats (e.g. JD) where very high precision (better than 64-bit precision) is required. Parameters ---------- val : numpy ndarray, list, str, number, or `~astropy.time.TimeDelta` object Data to initialize table. val2 : numpy ndarray, list, str, or number; optional Data to initialize table. format : str, optional Format of input value(s) scale : str, optional Time scale of input value(s) copy : bool, optional Make a copy of the input values """ SCALES = TIME_DELTA_SCALES """List of time delta scales.""" FORMATS = TIME_DELTA_FORMATS """Dict of time delta formats.""" def __init__(self, val, val2=None, format=None, scale=None, copy=False): if isinstance(val, self.__class__): if scale is not None: self._set_scale(scale) else: if format is None: try: val = val.to(u.day) if val2 is not None: val2 = val2.to(u.day) except: raise ValueError('Only Quantities with Time units can ' 'be used to initiate {0} instances .' .format(self.__class__.__name__)) format = 'jd' self._init_from_vals(val, val2, format, scale, copy) if scale is not None: self.SCALES = TIME_DELTA_TYPES[scale] def replicate(self, *args, **kwargs): out = super(TimeDelta, self).replicate(*args, **kwargs) out.SCALES = self.SCALES return out def _set_scale(self, scale): """ This is the key routine that actually does time scale conversions. This is not public and not connected to the read-only scale property. """ if scale == self.scale: return if scale not in self.SCALES: raise ValueError("Scale {0} is not in the allowed scales {1}" .format(repr(scale), sorted(self.SCALES))) # For TimeDelta, there can only be a change in scale factor, # which is written as time2 - time1 = scale_offset * time1 scale_offset = SCALE_OFFSETS[(self.scale, scale)] if scale_offset is None: self._time.scale = scale else: jd1, jd2 = self._time.jd1, self._time.jd2 offset1, offset2 = day_frac(jd1, jd2, factor=scale_offset) self._time = self.FORMATS[self.format]( jd1 + offset1, jd2 + offset2, scale, self.precision, self.in_subfmt, self.out_subfmt, from_jd=True) def __add__(self, other): # only deal with TimeDelta + TimeDelta if isinstance(other, Time): if not isinstance(other, TimeDelta): return other.__add__(self) else: try: other = TimeDelta(other) except: raise OperandTypeError(self, other, '+') # the scales should be compatible (e.g., cannot convert TDB to TAI) if(self.scale is not None and self.scale not in other.SCALES or other.scale is not None and other.scale not in self.SCALES): raise TypeError("Cannot add TimeDelta instances with scales " "'{0}' and '{1}'".format(self.scale, other.scale)) # adjust the scale of other if the scale of self is set (or no scales) if self.scale is not None or other.scale is None: out = self.replicate() if other.scale is not None: other = getattr(other, self.scale) else: out = other.replicate() jd1 = self._time.jd1 + other._time.jd1 jd2 = self._time.jd2 + other._time.jd2 out._time.jd1, out._time.jd2 = day_frac(jd1, jd2) out.isscalar = self.isscalar and other.isscalar return out def __sub__(self, other): # only deal with TimeDelta - TimeDelta if isinstance(other, Time): if not isinstance(other, TimeDelta): raise OperandTypeError(self, other, '-') else: try: other = TimeDelta(other) except: raise OperandTypeError(self, other, '-') # the scales should be compatible (e.g., cannot convert TDB to TAI) if(self.scale is not None and self.scale not in other.SCALES or other.scale is not None and other.scale not in self.SCALES): raise TypeError("Cannot subtract TimeDelta instances with scales " "'{0}' and '{1}'".format(self.scale, other.scale)) # adjust the scale of other if the scale of self is set (or no scales) if self.scale is not None or other.scale is None: out = self.replicate() if other.scale is not None: other = getattr(other, self.scale) else: out = other.replicate() jd1 = self._time.jd1 - other._time.jd1 jd2 = self._time.jd2 - other._time.jd2 out._time.jd1, out._time.jd2 = day_frac(jd1, jd2) out.isscalar = self.isscalar and other.isscalar return out def __neg__(self): """Negation of a `TimeDelta` object.""" new = self.copy() new._time.jd1 = -self._time.jd1 new._time.jd2 = -self._time.jd2 return new def __abs__(self): """Absolute value of a `TimeDelta` object.""" jd1, jd2 = self._time.jd1, self._time.jd2 negative = jd1 + jd2 < 0 new = self.copy() new._time.jd1 = np.where(negative, -jd1, jd1) new._time.jd2 = np.where(negative, -jd2, jd2) return new def __mul__(self, other): """Multiplication of `TimeDelta` objects by numbers/arrays.""" # check needed since otherwise the self.jd1 * other multiplication # would enter here again (via __rmul__) if isinstance(other, Time): raise OperandTypeError(self, other, '*') try: # convert to straight float if dimensionless quantity other = other.to(1) except: pass try: jd1, jd2 = day_frac(self.jd1, self.jd2, factor=other) except Exception as err: # try downgrading self to a quantity try: return self.to(u.day) * other except: raise err out = TimeDelta(jd1, jd2, format='jd', scale=self.scale) if self.format != 'jd': out = out.replicate(format=self.format) return out def __rmul__(self, other): """Multiplication of numbers/arrays with `TimeDelta` objects.""" return self.__mul__(other) def __div__(self, other): """Division of `TimeDelta` objects by numbers/arrays.""" return self.__truediv__(other) def __rdiv__(self, other): """Division by `TimeDelta` objects of numbers/arrays.""" return self.__rtruediv__(other) def __truediv__(self, other): """Division of `TimeDelta` objects by numbers/arrays.""" # cannot do __mul__(1./other) as that looses precision try: other = other.to(1) except: pass try: # convert to straight float if dimensionless quantity jd1, jd2 = day_frac(self.jd1, self.jd2, divisor=other) except Exception as err: # try downgrading self to a quantity try: return self.to(u.day) / other except: raise err out = TimeDelta(jd1, jd2, format='jd', scale=self.scale) if self.format != 'jd': out = out.replicate(format=self.format) return out def __rtruediv__(self, other): """Division by `TimeDelta` objects of numbers/arrays.""" return other / self.to(u.day) def to(self, *args, **kwargs): return u.Quantity(self._shaped_like_input(self._time.jd1 + self._time.jd2), u.day).to(*args, **kwargs) class TimeFormat(object): """ Base class for time representations. Parameters ---------- val1 : numpy ndarray, list, str, or number Data to initialize table. val2 : numpy ndarray, list, str, or number; optional Data to initialize table. scale : str Time scale of input value(s) precision : int Precision for seconds as floating point in_subfmt : str Select subformat for inputting string times out_subfmt : str Select subformat for outputting string times from_jd : bool If true then val1, val2 are jd1, jd2 """ def __init__(self, val1, val2, scale, precision, in_subfmt, out_subfmt, from_jd=False): self.scale = scale # validation of scale done later with _check_scale self.precision = precision self.in_subfmt = in_subfmt self.out_subfmt = out_subfmt if from_jd: self.jd1 = val1 self.jd2 = val2 else: val1, val2 = self._check_val_type(val1, val2) self.set_jds(val1, val2) def __len__(self): return len(self.jd1) @property def scale(self): """Time scale""" self._scale = self._check_scale(self._scale) return self._scale @scale.setter def scale(self, val): self._scale = val def _check_val_type(self, val1, val2): """Input value validation, typically overridden by derived classes""" try: assert (val1.dtype == np.double and (val2 is None or val2.dtype == np.double)) except: raise TypeError('Input values for {0} class must be doubles' .format(self.name)) if hasattr(val1, 'to'): # set possibly scaled unit any quantities should be converted to _unit = u.CompositeUnit(getattr(self, 'unit', 1.), [u.day], [1]) val1 = val1.to(_unit).value if val2 is not None: val2 = val2.to(_unit).value else: if hasattr(val2, 'to'): raise TypeError('Cannot mix float and Quantity inputs') if val2 is None: val2 = np.zeros_like(val1) return val1, val2 def _check_scale(self, scale): """ Return a validated scale value. If there is a class attribute 'scale' then that defines the default / required time scale for this format. In this case if a scale value was provided that needs to match the class default, otherwise return the class default. Otherwise just make sure that scale is in the allowed list of scales. Provide a different error message if `None` (no value) was supplied. """ if hasattr(self.__class__, 'epoch_scale') and scale is None: scale = self.__class__.epoch_scale if scale is None: scale = 'utc' # Default scale as of astropy 0.4 if scale not in TIME_SCALES: raise ScaleValueError("Scale value '{0}' not in " "allowed values {1}" .format(scale, TIME_SCALES)) return scale def set_jds(self, val1, val2): """ Set internal jd1 and jd2 from val1 and val2. Must be provided by derived classes. """ raise NotImplementedError @property def value(self): """ Return time representation from internal jd1 and jd2. Must be provided by derived classes. """ raise NotImplementedError class TimeJD(TimeFormat): """ Julian Date time format. This represents the number of days since the beginning of the Julian Period. For example, 2451544.5 in JD is midnight on January 1, 2000. """ name = 'jd' def set_jds(self, val1, val2): self._check_scale(self._scale) # Validate scale. self.jd1, self.jd2 = day_frac(val1, val2) @property def value(self): return self.jd1 + self.jd2 class TimeMJD(TimeFormat): """ Modified Julian Date time format. This represents the number of days since midnight on November 17, 1858. For example, 51544.0 in MJD is midnight on January 1, 2000. """ name = 'mjd' def set_jds(self, val1, val2): # TODO - this routine and vals should be Cythonized to follow the ERFA # convention of preserving precision by adding to the larger of the two # values in a vectorized operation. But in most practical cases the # first one is probably biggest. self._check_scale(self._scale) # Validate scale. self.jd1, self.jd2 = day_frac(val1, val2) self.jd1 += MJD_ZERO @property def value(self): return (self.jd1 - MJD_ZERO) + self.jd2 class TimeFromEpoch(TimeFormat): """ Base class for times that represent the interval from a particular epoch as a floating point multiple of a unit time interval (e.g. seconds or days). """ def __init__(self, val1, val2, scale, precision, in_subfmt, out_subfmt, from_jd=False): self.scale = scale # Initialize the reference epoch (a single time defined in subclasses) epoch = Time(self.epoch_val, self.epoch_val2, scale=self.epoch_scale, format=self.epoch_format) self.epoch = epoch # Now create the TimeFormat object as normal super(TimeFromEpoch, self).__init__(val1, val2, scale, precision, in_subfmt, out_subfmt, from_jd) def set_jds(self, val1, val2): """ Initialize the internal jd1 and jd2 attributes given val1 and val2. For an TimeFromEpoch subclass like TimeUnix these will be floats giving the effective seconds since an epoch time (e.g. 1970-01-01 00:00:00). """ # Form new JDs based on epoch time + time from epoch (converted to JD). # One subtlety that might not be obvious is that 1.000 Julian days in # UTC can be 86400 or 86401 seconds. For the TimeUnix format the # assumption is that every day is exactly 86400 seconds, so this is, in # principle, doing the math incorrectly, *except* that it matches the # definition of Unix time which does not include leap seconds. # note: use divisor=1./self.unit, since this is either 1 or 1/86400, # and 1/86400 is not exactly representable as a float64, so multiplying # by that will cause rounding errors. (But inverting it as a float64 # recovers the exact number) day, frac = day_frac(val1, val2, divisor=1. / self.unit) jd1 = self.epoch.jd1 + day jd2 = self.epoch.jd2 + frac # Create a temporary Time object corresponding to the new (jd1, jd2) in # the epoch scale (e.g. UTC for TimeUnix) then convert that to the # desired time scale for this object. # # A known limitation is that the transform from self.epoch_scale to # self.scale cannot involve any metadata like lat or lon. try: tm = getattr(Time(jd1, jd2, scale=self.epoch_scale, format='jd'), self.scale) except Exception as err: raise ScaleValueError("Cannot convert from '{0}' epoch scale '{1}'" "to specified scale '{2}', got error:\n{3}" .format(self.name, self.epoch_scale, self.scale, err)) self.jd1 = tm.jd1 self.jd2 = tm.jd2 @property def value(self): # when we get here, getattr will already have ensured our scale # equals epoch scale, so we can just subtract the epoch and convert time_from_epoch = ((self.jd1 - self.epoch.jd1) + (self.jd2 - self.epoch.jd2)) / self.unit return time_from_epoch class TimeUnix(TimeFromEpoch): """ Unix time: seconds from 1970-01-01 00:00:00 UTC. For example, 946684800.0 in Unix time is midnight on January 1, 2000. NOTE: this quantity is not exactly unix time and differs from the strict POSIX definition by up to 1 second on days with a leap second. POSIX unix time actually jumps backward by 1 second at midnight on leap second days while this class value is monotonically increasing at 86400 seconds per UTC day. """ name = 'unix' unit = 1.0 / SECS_PER_DAY # in days (1 day == 86400 seconds) epoch_val = '1970-01-01 00:00:00' epoch_val2 = None epoch_scale = 'utc' epoch_format = 'iso' class TimeCxcSec(TimeFromEpoch): """ Chandra X-ray Center seconds from 1998-01-01 00:00:00 TT. For example, 63072064.184 is midnight on January 1, 2000. """ name = 'cxcsec' unit = 1.0 / SECS_PER_DAY # in days (1 day == 86400 seconds) epoch_val = '1998-01-01 00:00:00' epoch_val2 = None epoch_scale = 'tt' epoch_format = 'iso' class TimeGPS(TimeFromEpoch): """GPS time: seconds from 1980-01-06 00:00:00 UTC For example, 630720013.0 is midnight on January 1, 2000. Notes ===== This implementation is strictly a representation of the number of seconds (including leap seconds) since midnight UTC on 1980-01-06. GPS can also be considered as a time scale which is ahead of TAI by a fixed offset (to within about 100 nanoseconds). For details, see http://tycho.usno.navy.mil/gpstt.html """ name = 'gps' unit = 1.0 / SECS_PER_DAY # in days (1 day == 86400 seconds) epoch_val = '1980-01-06 00:00:19' # above epoch is the same as Time('1980-01-06 00:00:00', scale='utc').tai epoch_val2 = None epoch_scale = 'tai' epoch_format = 'iso' class TimePlotDate(TimeFromEpoch): """ Matplotlib `~matplotlib.pyplot.plot_date` input: 1 + number of days from 0001-01-01 00:00:00 UTC This can be used directly in the matplotlib `~matplotlib.pyplot.plot_date` function:: >>> import matplotlib.pyplot as plt >>> jyear = np.linspace(2000, 2001, 20) >>> t = Time(jyear, format='jyear', scale='utc') >>> plt.plot_date(t.plot_date, jyear) >>> plt.gcf().autofmt_xdate() # orient date labels at a slant >>> plt.draw() For example, 730120.0003703703 is midnight on January 1, 2000. """ # This corresponds to the zero reference time for matplotlib plot_date(). # Note that TAI and UTC are equivalent at the reference time. name = 'plot_date' unit = 1.0 epoch_val = 1721424.5 # Time('0001-01-01 00:00:00', scale='tai').jd - 1 epoch_val2 = None epoch_scale = 'utc' epoch_format = 'jd' class TimeUnique(TimeFormat): """ Base class for time formats that can uniquely create a time object without requiring an explicit format specifier. This class does nothing but provide inheritance to identify a class as unique. """ class TimeAstropyTime(TimeUnique): """ Instantiate date from an Astropy Time object (or list thereof). This is purely for instantiating from a Time object. The output format is the same as the first time instance. """ name = 'astropy_time' def __new__(cls, val1, val2, scale, precision, in_subfmt, out_subfmt, from_jd=False): """ Use __new__ instead of __init__ to output a class instance that is the same as the class of the first Time object in the list. """ if not all(isinstance(val, Time) for val in val1): raise TypeError('Input values for {0} class must be datetime ' 'objects'.format(cls.name)) if scale is None: scale = val1[0].scale jd1 = np.concatenate([getattr(val, scale)._time.jd1 for val in val1]) jd2 = np.concatenate([getattr(val, scale)._time.jd2 for val in val1]) OutTimeFormat = val1[0]._time.__class__ self = OutTimeFormat(jd1, jd2, scale, precision, in_subfmt, out_subfmt, from_jd=True) return self class TimeDatetime(TimeUnique): """ Represent date as Python standard library `~datetime.datetime` object Example:: >>> from datetime import datetime >>> t = Time(datetime(2000, 1, 2, 12, 0, 0), scale='utc') >>> t.iso '2000-01-02 12:00:00.000' >>> t.tt.datetime datetime.datetime(2000, 1, 2, 12, 1, 4, 184000) """ name = 'datetime' def _check_val_type(self, val1, val2): # Note: don't care about val2 for this class try: assert all(isinstance(val, datetime) for val in val1) except: raise TypeError('Input values for {0} class must be ' 'datetime objects'.format(self.name)) return val1, None def set_jds(self, val1, val2): """Convert datetime object contained in val1 to jd1, jd2""" n_times = len(val1) iy = np.empty(n_times, dtype=np.intc) im = np.empty(n_times, dtype=np.intc) id = np.empty(n_times, dtype=np.intc) ihr = np.empty(n_times, dtype=np.intc) imin = np.empty(n_times, dtype=np.intc) dsec = np.empty(n_times, dtype=np.double) # Iterate through the datetime objects for i, val in enumerate(val1): iy[i] = val.year im[i] = val.month id[i] = val.day ihr[i] = val.hour imin[i] = val.minute dsec[i] = val.second + val.microsecond / 1e6 self.jd1, self.jd2 = erfa_time.dtf_jd( self.scale.upper().encode('utf8'), iy, im, id, ihr, imin, dsec) @property def value(self): iys, ims, ids, ihmsfs = erfa_time.jd_dtf(self.scale.upper() .encode('utf8'), 6, # precision=6 for microsec self.jd1, self.jd2) out = np.empty(len(self), dtype=np.object) idxs = itertools.count() for idx, iy, im, id, ihmsf in six.moves.zip(idxs, iys, ims, ids, ihmsfs): ihr, imin, isec, ifracsec = ihmsf out[idx] = datetime(int(iy), int(im), int(id), int(ihr), int(imin), int(isec), int(ifracsec)) return out class TimeString(TimeUnique): """ Base class for string-like time represetations. This class assumes that anything following the last decimal point to the right is a fraction of a second. This is a reference implementation can be made much faster with effort. """ def _check_val_type(self, val1, val2): # Note: don't care about val2 for these classes try: assert val1.dtype.kind in ('S', 'U') except: raise TypeError('Input values for {0} class must be strings' .format(self.name)) return val1, None def set_jds(self, val1, val2): """Parse the time strings contained in val1 and set jd1, jd2""" n_times = len(val1) # val1,2 already checked to have same len iy = np.empty(n_times, dtype=np.intc) im = np.empty(n_times, dtype=np.intc) id = np.empty(n_times, dtype=np.intc) ihr = np.empty(n_times, dtype=np.intc) imin = np.empty(n_times, dtype=np.intc) dsec = np.empty(n_times, dtype=np.double) # Select subformats based on current self.in_subfmt subfmts = self._select_subfmts(self.in_subfmt) for i, timestr in enumerate(val1): # Assume that anything following "." on the right side is a # floating fraction of a second. # Handle trailing 'Z' for UTC time if timestr.endswith('Z'): if self.scale != 'utc': raise ValueError("Time input terminating in 'Z' must have scale='UTC'") timestr = timestr[:-1] try: idot = timestr.rindex('.') except: fracsec = 0.0 else: timestr, fracsec = timestr[:idot], timestr[idot:] fracsec = float(fracsec) for _, strptime_fmt, _ in subfmts: try: tm = time.strptime(timestr, strptime_fmt) except ValueError: pass else: iy[i] = tm.tm_year im[i] = tm.tm_mon id[i] = tm.tm_mday ihr[i] = tm.tm_hour imin[i] = tm.tm_min dsec[i] = tm.tm_sec + fracsec break else: raise ValueError('Time {0} does not match {1} format' .format(timestr, self.name)) self.jd1, self.jd2 = erfa_time.dtf_jd( self.scale.upper().encode('utf8'), iy, im, id, ihr, imin, dsec) def str_kwargs(self): """ Generator that yields a dict of values corresponding to the calendar date and time for the internal JD values. """ iys, ims, ids, ihmsfs = erfa_time.jd_dtf(self.scale.upper() .encode('utf8'), self.precision, self.jd1, self.jd2) # Get the str_fmt element of the first allowed output subformat _, _, str_fmt = self._select_subfmts(self.out_subfmt)[0] if '{yday:' in str_fmt: has_yday = True else: has_yday = False yday = None for iy, im, id, ihmsf in six.moves.zip(iys, ims, ids, ihmsfs): ihr, imin, isec, ifracsec = ihmsf if has_yday: yday = datetime(iy, im, id).timetuple().tm_yday yield {'year': int(iy), 'mon': int(im), 'day': int(id), 'hour': int(ihr), 'min': int(imin), 'sec': int(isec), 'fracsec': int(ifracsec), 'yday': yday} @property def value(self): # Select the first available subformat based on current # self.out_subfmt subfmts = self._select_subfmts(self.out_subfmt) _, _, str_fmt = subfmts[0] # TODO: fix this ugly hack if self.precision > 0 and str_fmt.endswith('{sec:02d}'): str_fmt += '.{fracsec:0' + str(self.precision) + 'd}' # Try to optimize this later. Can't pre-allocate because length of # output could change, e.g. year rolls from 999 to 1000. outs = [] for kwargs in self.str_kwargs(): outs.append(str(str_fmt.format(**kwargs))) return np.array(outs) def _select_subfmts(self, pattern): """ Return a list of subformats where name matches ``pattern`` using fnmatch. """ fnmatchcase = fnmatch.fnmatchcase subfmts = [x for x in self.subfmts if fnmatchcase(x[0], pattern)] if len(subfmts) == 0: raise ValueError('No subformats match {0}'.format(pattern)) return subfmts class TimeISO(TimeString): """ ISO 8601 compliant date-time format "YYYY-MM-DD HH:MM:SS.sss...". For example, 2000-01-01 00:00:00.000 is midnight on January 1, 2000. The allowed subformats are: - 'date_hms': date + hours, mins, secs (and optional fractional secs) - 'date_hm': date + hours, mins - 'date': date """ name = 'iso' subfmts = (('date_hms', '%Y-%m-%d %H:%M:%S', # XXX To Do - use strftime for output ?? '{year:d}-{mon:02d}-{day:02d} {hour:02d}:{min:02d}:{sec:02d}'), ('date_hm', '%Y-%m-%d %H:%M', '{year:d}-{mon:02d}-{day:02d} {hour:02d}:{min:02d}'), ('date', '%Y-%m-%d', '{year:d}-{mon:02d}-{day:02d}')) class TimeISOT(TimeString): """ ISO 8601 compliant date-time format "YYYY-MM-DDTHH:MM:SS.sss...". This is the same as TimeISO except for a "T" instead of space between the date and time. For example, 2000-01-01T00:00:00.000 is midnight on January 1, 2000. The allowed subformats are: - 'date_hms': date + hours, mins, secs (and optional fractional secs) - 'date_hm': date + hours, mins - 'date': date """ name = 'isot' subfmts = (('date_hms', '%Y-%m-%dT%H:%M:%S', '{year:d}-{mon:02d}-{day:02d}T{hour:02d}:{min:02d}:{sec:02d}'), ('date_hm', '%Y-%m-%dT%H:%M', '{year:d}-{mon:02d}-{day:02d}T{hour:02d}:{min:02d}'), ('date', '%Y-%m-%d', '{year:d}-{mon:02d}-{day:02d}')) class TimeYearDayTime(TimeString): """ Year, day-of-year and time as "YYYY:DOY:HH:MM:SS.sss...". The day-of-year (DOY) goes from 001 to 365 (366 in leap years). For example, 2000:001:00:00:00.000 is midnight on January 1, 2000. The allowed subformats are: - 'date_hms': date + hours, mins, secs (and optional fractional secs) - 'date_hm': date + hours, mins - 'date': date """ name = 'yday' subfmts = (('date_hms', '%Y:%j:%H:%M:%S', '{year:d}:{yday:03d}:{hour:02d}:{min:02d}:{sec:02d}'), ('date_hm', '%Y:%j:%H:%M', '{year:d}:{yday:03d}:{hour:02d}:{min:02d}'), ('date', '%Y:%j', '{year:d}:{yday:03d}')) class TimeEpochDate(TimeFormat): """ Base class for support floating point Besselian and Julian epoch dates """ def set_jds(self, val1, val2): self._check_scale(self._scale) # validate scale. epoch_to_jd = getattr(erfa_time, self.epoch_to_jd) jd1, jd2 = epoch_to_jd(val1 + val2) self.jd1, self.jd2 = day_frac(jd1, jd2) @property def value(self): jd_to_epoch = getattr(erfa_time, self.jd_to_epoch) return jd_to_epoch(self.jd1, self.jd2) class TimeBesselianEpoch(TimeEpochDate): """Besselian Epoch year as floating point value(s) like 1950.0""" name = 'byear' epoch_to_jd = 'besselian_epoch_jd' jd_to_epoch = 'jd_besselian_epoch' def _check_val_type(self, val1, val2): """Input value validation, typically overridden by derived classes""" if hasattr(val1, 'to') and hasattr(val1, 'unit'): raise ValueError("Cannot use Quantities for 'byear' format, " "as the interpretation would be ambiguous. " "Use float with Besselian year instead. ") return super(TimeBesselianEpoch, self)._check_val_type(val1, val2) class TimeJulianEpoch(TimeEpochDate): """Julian Epoch year as floating point value(s) like 2000.0""" name = 'jyear' unit = 365.25 # Length of the Julian year, for conversion to quantities epoch_to_jd = 'julian_epoch_jd' jd_to_epoch = 'jd_julian_epoch' class TimeEpochDateString(TimeString): """ Base class to support string Besselian and Julian epoch dates such as 'B1950.0' or 'J2000.0' respectively. """ def set_jds(self, val1, val2): years = np.empty(len(val1), dtype=np.double) epoch_prefix = self.epoch_prefix for i, time_str in enumerate(val1): try: epoch_type, year_str = time_str[0], time_str[1:] year = float(year_str) if epoch_type.upper() != epoch_prefix: raise ValueError except (IndexError, ValueError): raise ValueError('Time {0} does not match {1} format' .format(time_str, self.name)) else: years[i] = year self._check_scale(self._scale) # validate scale. epoch_to_jd = getattr(erfa_time, self.epoch_to_jd) self.jd1, self.jd2 = epoch_to_jd(years) @property def value(self): jd_to_epoch = getattr(erfa_time, self.jd_to_epoch) years = jd_to_epoch(self.jd1, self.jd2) # Use old-style format since it is a factor of 2 faster str_fmt = self.epoch_prefix + '%.' + str(self.precision) + 'f' outs = [str_fmt % year for year in years] return np.array(outs) class TimeBesselianEpochString(TimeEpochDateString): """Besselian Epoch year as string value(s) like 'B1950.0'""" name = 'byear_str' epoch_to_jd = 'besselian_epoch_jd' jd_to_epoch = 'jd_besselian_epoch' epoch_prefix = 'B' class TimeJulianEpochString(TimeEpochDateString): """Julian Epoch year as string value(s) like 'J2000.0'""" name = 'jyear_str' epoch_to_jd = 'julian_epoch_jd' jd_to_epoch = 'jd_julian_epoch' epoch_prefix = 'J' class TimeDeltaFormat(TimeFormat): """Base class for time delta representations""" def _check_scale(self, scale): """ Check that the scale is in the allowed list of scales, or is `None` """ if scale is not None and scale not in TIME_DELTA_SCALES: raise ScaleValueError("Scale value '{0}' not in " "allowed values {1}" .format(scale, TIME_DELTA_SCALES)) return scale def set_jds(self, val1, val2): self._check_scale(self._scale) # Validate scale. self.jd1, self.jd2 = day_frac(val1, val2, divisor=1./self.unit) @property def value(self): return (self.jd1 + self.jd2) / self.unit class TimeDeltaSec(TimeDeltaFormat): """Time delta in SI seconds""" name = 'sec' unit = 1. / SECS_PER_DAY # for quantity input class TimeDeltaJD(TimeDeltaFormat): """Time delta in Julian days (86400 SI seconds)""" name = 'jd' unit = 1. class ScaleValueError(Exception): pass # Set module constant with names of all available time formats for name, val in list(six.iteritems(locals())): try: is_timeformat = issubclass(val, TimeFormat) is_timedeltaformat = issubclass(val, TimeDeltaFormat) except: pass else: if hasattr(val, 'name'): if is_timedeltaformat: TIME_DELTA_FORMATS[val.name] = val elif is_timeformat: TIME_FORMATS[val.name] = val def _make_1d_array(val, copy=False): """ Take ``val`` and convert/reshape to a 1-d array. If ``copy`` is `True` then copy input values. Returns ------- val, val_ndim: ndarray, int Array version of ``val`` and the number of dims in original. """ val = np.array(val, copy=copy, subok=True) val_ndim = val.ndim # remember original ndim if val.ndim == 0: val = np.atleast_1d(val) elif val_ndim > 1: # Maybe lift this restriction later to allow multi-dim in/out? raise TypeError('Input val must be zero or one dimensional') # Allow only float64, string or object arrays as input # (object is for datetime, maybe add more specific test later?) # This also ensures the right byteorder for float64 (closes #2942). if not (val.dtype == np.float64 or val.dtype.kind in 'OSUa'): val = np.asanyarray(val, dtype=np.float64) return val, val_ndim def day_frac(val1, val2, factor=1., divisor=1.): """ Return the sum of ``val1`` and ``val2`` as two float64s, an integer part and the fractional remainder. If ``factor`` is not 1.0 then multiply the sum by ``factor``. If ``divisor`` is not 1.0 then divide the sum by ``divisor``. The arithmetic is all done with exact floating point operations so no precision is lost to rounding error. This routine assumes the sum is less than about 1e16, otherwise the ``frac`` part will be greater than 1.0. Returns ------- day, frac: float64 Integer and fractional part of val1 + val2. """ # Add val1 and val2 exactly, returning the result as two float64s. # The first is the approximate sum (with some floating point error) # and the second is the error of the float64 sum. sum12, err12 = two_sum(val1, val2) if np.any(factor != 1.): sum12, carry = two_product(sum12, factor) carry += err12 * factor sum12, err12 = two_sum(sum12, carry) if np.any(divisor != 1.): q1 = sum12 / divisor p1, p2 = two_product(q1, divisor) d1, d2 = two_sum(sum12, -p1) d2 += err12 d2 -= p2 q2 = (d1 + d2) / divisor # 3-part float fine here; nothing can be lost sum12, err12 = two_sum(q1, q2) # get integer fraction day = np.round(sum12) extra, frac = two_sum(sum12, -day) frac += extra + err12 return day, frac def two_sum(a, b): """ Add ``a`` and ``b`` exactly, returning the result as two float64s. The first is the approximate sum (with some floating point error) and the second is the error of the float64 sum. Using the procedure of Shewchuk, 1997, Discrete & Computational Geometry 18(3):305-363 http://www.cs.berkeley.edu/~jrs/papers/robustr.pdf Returns ------- sum, err: float64 Approximate sum of a + b and the exact floating point error """ x = a + b eb = x - a eb = b - eb ea = x - b ea = a - ea return x, ea + eb def two_product(a, b): """ Multiple ``a`` and ``b`` exactly, returning the result as two float64s. The first is the approximate prodcut (with some floating point error) and the second is the error of the float64 product. Uses the procedure of Shewchuk, 1997, Discrete & Computational Geometry 18(3):305-363 http://www.cs.berkeley.edu/~jrs/papers/robustr.pdf Returns ------- prod, err: float64 Approximate product a * b and the exact floating point error """ x = a * b ah, al = split(a) bh, bl = split(b) y1 = ah * bh y = x - y1 y2 = al * bh y -= y2 y3 = ah * bl y -= y3 y4 = al * bl y = y4 - y return x, y def split(a): """ Split float64 in two aligned parts. Uses the procedure of Shewchuk, 1997, Discrete & Computational Geometry 18(3):305-363 http://www.cs.berkeley.edu/~jrs/papers/robustr.pdf """ c = 134217729. * a # 2**27+1. abig = c - a ah = c - abig al = a - ah return ah, al class OperandTypeError(TypeError): def __init__(self, left, right, op=None): op_string = '' if op is None else ' for {0}'.format(op) super(OperandTypeError, self).__init__( "Unsupported operand type(s){0}: " "'{1}' and '{2}'".format(op_string, left.__class__.__name__, right.__class__.__name__))