testbed/astropy__astropy/astropy/coordinates/angles.py

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

"""
This module contains the fundamental classes used for representing
coordinates in astropy.
"""

from collections import namedtuple

import numpy as np

from . import angle_utilities as util
from astropy import units as u
from astropy.utils import isiterable
from astropy.utils.compat import NUMPY_LT_1_14_1, NUMPY_LT_1_14_2

__all__ = ['Angle', 'Latitude', 'Longitude']


# these are used by the `hms` and `dms` attributes
hms_tuple = namedtuple('hms_tuple', ('h', 'm', 's'))
dms_tuple = namedtuple('dms_tuple', ('d', 'm', 's'))
signed_dms_tuple = namedtuple('signed_dms_tuple', ('sign', 'd', 'm', 's'))


class Angle(u.SpecificTypeQuantity):
    """
    One or more angular value(s) with units equivalent to radians or degrees.

    An angle can be specified either as an array, scalar, tuple (see
    below), string, `~astropy.units.Quantity` or another
    :class:`~astropy.coordinates.Angle`.

    The input parser is flexible and supports a variety of formats::

      Angle('10.2345d')
      Angle(['10.2345d', '-20d'])
      Angle('1:2:30.43 degrees')
      Angle('1 2 0 hours')
      Angle(np.arange(1, 8), unit=u.deg)
      Angle('1°2′3″')
      Angle('1d2m3.4s')
      Angle('-1h2m3s')
      Angle('-1h2.5m')
      Angle('-1:2.5', unit=u.deg)
      Angle((10, 11, 12), unit='hourangle')  # (h, m, s)
      Angle((-1, 2, 3), unit=u.deg)  # (d, m, s)
      Angle(10.2345 * u.deg)
      Angle(Angle(10.2345 * u.deg))

    Parameters
    ----------
    angle : `~numpy.array`, scalar, `~astropy.units.Quantity`, :class:`~astropy.coordinates.Angle`
        The angle value. If a tuple, will be interpreted as ``(h, m,
        s)`` or ``(d, m, s)`` depending on ``unit``. If a string, it
        will be interpreted following the rules described above.

        If ``angle`` is a sequence or array of strings, the resulting
        values will be in the given ``unit``, or if `None` is provided,
        the unit will be taken from the first given value.

    unit : `~astropy.units.UnitBase`, str, optional
        The unit of the value specified for the angle.  This may be
        any string that `~astropy.units.Unit` understands, but it is
        better to give an actual unit object.  Must be an angular
        unit.

    dtype : `~numpy.dtype`, optional
        See `~astropy.units.Quantity`.

    copy : bool, optional
        See `~astropy.units.Quantity`.

    Raises
    ------
    `~astropy.units.UnitsError`
        If a unit is not provided or it is not an angular unit.
    """
    _equivalent_unit = u.radian
    _include_easy_conversion_members = True

    def __new__(cls, angle, unit=None, dtype=None, copy=True):

        if not isinstance(angle, u.Quantity):
            if unit is not None:
                unit = cls._convert_unit_to_angle_unit(u.Unit(unit))

            if isinstance(angle, tuple):
                angle = cls._tuple_to_float(angle, unit)

            elif isinstance(angle, str):
                angle, angle_unit = util.parse_angle(angle, unit)
                if angle_unit is None:
                    angle_unit = unit

                if isinstance(angle, tuple):
                    angle = cls._tuple_to_float(angle, angle_unit)

                if angle_unit is not unit:
                    # Possible conversion to `unit` will be done below.
                    angle = u.Quantity(angle, angle_unit, copy=False)

            elif (isiterable(angle) and
                  not (isinstance(angle, np.ndarray) and
                       angle.dtype.kind not in 'SUVO')):
                angle = [Angle(x, unit, copy=False) for x in angle]

        return super().__new__(cls, angle, unit, dtype=dtype, copy=copy)

    @staticmethod
    def _tuple_to_float(angle, unit):
        """
        Converts an angle represented as a 3-tuple or 2-tuple into a floating
        point number in the given unit.
        """
        # TODO: Numpy array of tuples?
        if unit == u.hourangle:
            return util.hms_to_hours(*angle)
        elif unit == u.degree:
            return util.dms_to_degrees(*angle)
        else:
            raise u.UnitsError("Can not parse '{0}' as unit '{1}'"
                               .format(angle, unit))

    @staticmethod
    def _convert_unit_to_angle_unit(unit):
        return u.hourangle if unit is u.hour else unit

    def _set_unit(self, unit):
        super()._set_unit(self._convert_unit_to_angle_unit(unit))

    @property
    def hour(self):
        """
        The angle's value in hours (read-only property).
        """
        return self.hourangle

    @property
    def hms(self):
        """
        The angle's value in hours, as a named tuple with ``(h, m, s)``
        members.  (This is a read-only property.)
        """
        return hms_tuple(*util.hours_to_hms(self.hourangle))

    @property
    def dms(self):
        """
        The angle's value in degrees, as a named tuple with ``(d, m, s)``
        members.  (This is a read-only property.)
        """
        return dms_tuple(*util.degrees_to_dms(self.degree))

    @property
    def signed_dms(self):
        """
        The angle's value in degrees, as a named tuple with ``(sign, d, m, s)``
        members.  The ``d``, ``m``, ``s`` are thus always positive, and the sign of
        the angle is given by ``sign``. (This is a read-only property.)

        This is primarily intended for use with `dms` to generate string
        representations of coordinates that are correct for negative angles.
        """
        return signed_dms_tuple(np.sign(self.degree),
                                *util.degrees_to_dms(np.abs(self.degree)))

    def to_string(self, unit=None, decimal=False, sep='fromunit',
                  precision=None, alwayssign=False, pad=False,
                  fields=3, format=None):
        """ A string representation of the angle.

        Parameters
        ----------
        unit : `~astropy.units.UnitBase`, optional
            Specifies the unit.  Must be an angular unit.  If not
            provided, the unit used to initialize the angle will be
            used.

        decimal : bool, optional
            If `True`, a decimal representation will be used, otherwise
            the returned string will be in sexagesimal form.

        sep : str, optional
            The separator between numbers in a sexagesimal
            representation.  E.g., if it is ':', the result is
            ``'12:41:11.1241'``. Also accepts 2 or 3 separators. E.g.,
            ``sep='hms'`` would give the result ``'12h41m11.1241s'``, or
            sep='-:' would yield ``'11-21:17.124'``.  Alternatively, the
            special string 'fromunit' means 'dms' if the unit is
            degrees, or 'hms' if the unit is hours.

        precision : int, optional
            The level of decimal precision.  If ``decimal`` is `True`,
            this is the raw precision, otherwise it gives the
            precision of the last place of the sexagesimal
            representation (seconds).  If `None`, or not provided, the
            number of decimal places is determined by the value, and
            will be between 0-8 decimal places as required.

        alwayssign : bool, optional
            If `True`, include the sign no matter what.  If `False`,
            only include the sign if it is negative.

        pad : bool, optional
            If `True`, include leading zeros when needed to ensure a
            fixed number of characters for sexagesimal representation.

        fields : int, optional
            Specifies the number of fields to display when outputting
            sexagesimal notation.  For example:

                - fields == 1: ``'5d'``
                - fields == 2: ``'5d45m'``
                - fields == 3: ``'5d45m32.5s'``

            By default, all fields are displayed.

        format : str, optional
            The format of the result.  If not provided, an unadorned
            string is returned.  Supported values are:

            - 'latex': Return a LaTeX-formatted string

            - 'unicode': Return a string containing non-ASCII unicode
              characters, such as the degree symbol

        Returns
        -------
        strrepr : str or array
            A string representation of the angle. If the angle is an array, this
            will be an array with a unicode dtype.


        """
        if unit is None:
            unit = self.unit
        else:
            unit = self._convert_unit_to_angle_unit(u.Unit(unit))

        separators = {
            None: {
                u.degree: 'dms',
                u.hourangle: 'hms'},
            'latex': {
                u.degree: [r'^\circ', r'{}^\prime', r'{}^{\prime\prime}'],
                u.hourangle: [r'^\mathrm{h}', r'^\mathrm{m}', r'^\mathrm{s}']},
            'unicode': {
                u.degree: '°′″',
                u.hourangle: 'ʰᵐˢ'}
            }

        if sep == 'fromunit':
            if format not in separators:
                raise ValueError("Unknown format '{0}'".format(format))
            seps = separators[format]
            if unit in seps:
                sep = seps[unit]

        # Create an iterator so we can format each element of what
        # might be an array.
        if unit is u.degree:
            if decimal:
                values = self.degree
                if precision is not None:
                    func = ("{0:0." + str(precision) + "f}").format
                else:
                    func = '{0:g}'.format
            else:
                if sep == 'fromunit':
                    sep = 'dms'
                values = self.degree
                func = lambda x: util.degrees_to_string(
                    x, precision=precision, sep=sep, pad=pad,
                    fields=fields)

        elif unit is u.hourangle:
            if decimal:
                values = self.hour
                if precision is not None:
                    func = ("{0:0." + str(precision) + "f}").format
                else:
                    func = '{0:g}'.format
            else:
                if sep == 'fromunit':
                    sep = 'hms'
                values = self.hour
                func = lambda x: util.hours_to_string(
                    x, precision=precision, sep=sep, pad=pad,
                    fields=fields)

        elif unit.is_equivalent(u.radian):
            if decimal:
                values = self.to_value(unit)
                if precision is not None:
                    func = ("{0:1." + str(precision) + "f}").format
                else:
                    func = "{0:g}".format
            elif sep == 'fromunit':
                values = self.to_value(unit)
                unit_string = unit.to_string(format=format)
                if format == 'latex':
                    unit_string = unit_string[1:-1]

                if precision is not None:
                    def plain_unit_format(val):
                        return ("{0:0." + str(precision) + "f}{1}").format(
                            val, unit_string)
                    func = plain_unit_format
                else:
                    def plain_unit_format(val):
                        return "{0:g}{1}".format(val, unit_string)
                    func = plain_unit_format
            else:
                raise ValueError(
                    "'{0}' can not be represented in sexagesimal "
                    "notation".format(
                        unit.name))

        else:
            raise u.UnitsError(
                "The unit value provided is not an angular unit.")

        def do_format(val):
            s = func(float(val))
            if alwayssign and not s.startswith('-'):
                s = '+' + s
            if format == 'latex':
                s = '${0}$'.format(s)
            return s

        format_ufunc = np.vectorize(do_format, otypes=['U'])
        result = format_ufunc(values)

        if result.ndim == 0:
            result = result[()]
        return result

    def wrap_at(self, wrap_angle, inplace=False):
        """
        Wrap the `Angle` object at the given ``wrap_angle``.

        This method forces all the angle values to be within a contiguous
        360 degree range so that ``wrap_angle - 360d <= angle <
        wrap_angle``. By default a new Angle object is returned, but if the
        ``inplace`` argument is `True` then the `Angle` object is wrapped in
        place and nothing is returned.

        For instance::

          >>> from astropy.coordinates import Angle
          >>> import astropy.units as u
          >>> a = Angle([-20.0, 150.0, 350.0] * u.deg)

          >>> a.wrap_at(360 * u.deg).degree  # Wrap into range 0 to 360 degrees  # doctest: +FLOAT_CMP
          array([340., 150., 350.])

          >>> a.wrap_at('180d', inplace=True)  # Wrap into range -180 to 180 degrees  # doctest: +FLOAT_CMP
          >>> a.degree  # doctest: +FLOAT_CMP
          array([-20., 150., -10.])

        Parameters
        ----------
        wrap_angle : str, `Angle`, angular `~astropy.units.Quantity`
            Specifies a single value for the wrap angle.  This can be any
            object that can initialize an `Angle` object, e.g. ``'180d'``,
            ``180 * u.deg``, or ``Angle(180, unit=u.deg)``.

        inplace : bool
            If `True` then wrap the object in place instead of returning
            a new `Angle`

        Returns
        -------
        out : Angle or `None`
            If ``inplace is False`` (default), return new `Angle` object
            with angles wrapped accordingly.  Otherwise wrap in place and
            return `None`.
        """
        wrap_angle = Angle(wrap_angle)  # Convert to an Angle
        wrapped = np.mod(self - wrap_angle, 360.0 * u.deg) - (360.0 * u.deg - wrap_angle)

        if inplace:
            self[()] = wrapped
        else:
            return wrapped

    def is_within_bounds(self, lower=None, upper=None):
        """
        Check if all angle(s) satisfy ``lower <= angle < upper``

        If ``lower`` is not specified (or `None`) then no lower bounds check is
        performed.  Likewise ``upper`` can be left unspecified.  For example::

          >>> from astropy.coordinates import Angle
          >>> import astropy.units as u
          >>> a = Angle([-20, 150, 350] * u.deg)
          >>> a.is_within_bounds('0d', '360d')
          False
          >>> a.is_within_bounds(None, '360d')
          True
          >>> a.is_within_bounds(-30 * u.deg, None)
          True

        Parameters
        ----------
        lower : str, `Angle`, angular `~astropy.units.Quantity`, `None`
            Specifies lower bound for checking.  This can be any object
            that can initialize an `Angle` object, e.g. ``'180d'``,
            ``180 * u.deg``, or ``Angle(180, unit=u.deg)``.
        upper : str, `Angle`, angular `~astropy.units.Quantity`, `None`
            Specifies upper bound for checking.  This can be any object
            that can initialize an `Angle` object, e.g. ``'180d'``,
            ``180 * u.deg``, or ``Angle(180, unit=u.deg)``.

        Returns
        -------
        is_within_bounds : bool
            `True` if all angles satisfy ``lower <= angle < upper``
        """
        ok = True
        if lower is not None:
            ok &= np.all(Angle(lower) <= self)
        if ok and upper is not None:
            ok &= np.all(self < Angle(upper))
        return bool(ok)

    def _str_helper(self, format=None):
        if self.isscalar:
            return self.to_string(format=format)

        if NUMPY_LT_1_14_1 or not NUMPY_LT_1_14_2:
            def formatter(x):
                return x.to_string(format=format)
        else:
            # In numpy 1.14.1, array2print formatters get passed plain numpy scalars instead
            # of subclass array scalars, so we need to recreate an array scalar.
            def formatter(x):
                return self._new_view(x).to_string(format=format)

        return np.array2string(self, formatter={'all': formatter})

    def __str__(self):
        return self._str_helper()

    def _repr_latex_(self):
        return self._str_helper(format='latex')


def _no_angle_subclass(obj):
    """Return any Angle subclass objects as an Angle objects.

    This is used to ensure that Latitude and Longitude change to Angle
    objects when they are used in calculations (such as lon/2.)
    """
    if isinstance(obj, tuple):
        return tuple(_no_angle_subclass(_obj) for _obj in obj)

    return obj.view(Angle) if isinstance(obj, Angle) else obj


class Latitude(Angle):
    """
    Latitude-like angle(s) which must be in the range -90 to +90 deg.

    A Latitude object is distinguished from a pure
    :class:`~astropy.coordinates.Angle` by virtue of being constrained
    so that::

      -90.0 * u.deg <= angle(s) <= +90.0 * u.deg

    Any attempt to set a value outside that range will result in a
    `ValueError`.

    The input angle(s) can be specified either as an array, list,
    scalar, tuple (see below), string,
    :class:`~astropy.units.Quantity` or another
    :class:`~astropy.coordinates.Angle`.

    The input parser is flexible and supports all of the input formats
    supported by :class:`~astropy.coordinates.Angle`.

    Parameters
    ----------
    angle : array, list, scalar, `~astropy.units.Quantity`, `Angle`. The
        angle value(s). If a tuple, will be interpreted as ``(h, m, s)`` or
        ``(d, m, s)`` depending on ``unit``. If a string, it will be
        interpreted following the rules described for
        :class:`~astropy.coordinates.Angle`.

        If ``angle`` is a sequence or array of strings, the resulting
        values will be in the given ``unit``, or if `None` is provided,
        the unit will be taken from the first given value.

    unit : :class:`~astropy.units.UnitBase`, str, optional
        The unit of the value specified for the angle.  This may be
        any string that `~astropy.units.Unit` understands, but it is
        better to give an actual unit object.  Must be an angular
        unit.

    Raises
    ------
    `~astropy.units.UnitsError`
        If a unit is not provided or it is not an angular unit.
    `TypeError`
        If the angle parameter is an instance of :class:`~astropy.coordinates.Longitude`.
    """
    def __new__(cls, angle, unit=None, **kwargs):
        # Forbid creating a Lat from a Long.
        if isinstance(angle, Longitude):
            raise TypeError("A Latitude angle cannot be created from a Longitude angle")
        self = super().__new__(cls, angle, unit=unit, **kwargs)
        self._validate_angles()
        return self

    def _validate_angles(self, angles=None):
        """Check that angles are between -90 and 90 degrees.
        If not given, the check is done on the object itself"""
        # Convert the lower and upper bounds to the "native" unit of
        # this angle.  This limits multiplication to two values,
        # rather than the N values in `self.value`.  Also, the
        # comparison is performed on raw arrays, rather than Quantity
        # objects, for speed.
        if angles is None:
            angles = self
        lower = u.degree.to(angles.unit, -90.0)
        upper = u.degree.to(angles.unit, 90.0)
        if np.any(angles.value < lower) or np.any(angles.value > upper):
            raise ValueError('Latitude angle(s) must be within -90 deg <= angle <= 90 deg, '
                             'got {0}'.format(angles.to(u.degree)))

    def __setitem__(self, item, value):
        # Forbid assigning a Long to a Lat.
        if isinstance(value, Longitude):
            raise TypeError("A Longitude angle cannot be assigned to a Latitude angle")
        # first check bounds
        self._validate_angles(value)
        super().__setitem__(item, value)

    # Any calculation should drop to Angle
    def __array_ufunc__(self, *args, **kwargs):
        results = super().__array_ufunc__(*args, **kwargs)
        return _no_angle_subclass(results)


class LongitudeInfo(u.QuantityInfo):
    _represent_as_dict_attrs = u.QuantityInfo._represent_as_dict_attrs + ('wrap_angle',)


class Longitude(Angle):
    """
    Longitude-like angle(s) which are wrapped within a contiguous 360 degree range.

    A ``Longitude`` object is distinguished from a pure
    :class:`~astropy.coordinates.Angle` by virtue of a ``wrap_angle``
    property.  The ``wrap_angle`` specifies that all angle values
    represented by the object will be in the range::

      wrap_angle - 360 * u.deg <= angle(s) < wrap_angle

    The default ``wrap_angle`` is 360 deg.  Setting ``wrap_angle=180 *
    u.deg`` would instead result in values between -180 and +180 deg.
    Setting the ``wrap_angle`` attribute of an existing ``Longitude``
    object will result in re-wrapping the angle values in-place.

    The input angle(s) can be specified either as an array, list,
    scalar, tuple, string, :class:`~astropy.units.Quantity`
    or another :class:`~astropy.coordinates.Angle`.

    The input parser is flexible and supports all of the input formats
    supported by :class:`~astropy.coordinates.Angle`.

    Parameters
    ----------
    angle : array, list, scalar, `~astropy.units.Quantity`,
        :class:`~astropy.coordinates.Angle` The angle value(s). If a tuple,
        will be interpreted as ``(h, m s)`` or ``(d, m, s)`` depending
        on ``unit``. If a string, it will be interpreted following the
        rules described for :class:`~astropy.coordinates.Angle`.

        If ``angle`` is a sequence or array of strings, the resulting
        values will be in the given ``unit``, or if `None` is provided,
        the unit will be taken from the first given value.

    unit : :class:`~astropy.units.UnitBase`, str, optional
        The unit of the value specified for the angle.  This may be
        any string that `~astropy.units.Unit` understands, but it is
        better to give an actual unit object.  Must be an angular
        unit.

    wrap_angle : :class:`~astropy.coordinates.Angle` or equivalent, or None
        Angle at which to wrap back to ``wrap_angle - 360 deg``.
        If ``None`` (default), it will be taken to be 360 deg unless ``angle``
        has a ``wrap_angle`` attribute already (i.e., is a ``Longitude``),
        in which case it will be taken from there.

    Raises
    ------
    `~astropy.units.UnitsError`
        If a unit is not provided or it is not an angular unit.
    `TypeError`
        If the angle parameter is an instance of :class:`~astropy.coordinates.Latitude`.
    """

    _wrap_angle = None
    _default_wrap_angle = Angle(360 * u.deg)
    info = LongitudeInfo()

    def __new__(cls, angle, unit=None, wrap_angle=None, **kwargs):
        # Forbid creating a Long from a Lat.
        if isinstance(angle, Latitude):
            raise TypeError("A Longitude angle cannot be created from "
                            "a Latitude angle.")
        self = super().__new__(cls, angle, unit=unit, **kwargs)
        if wrap_angle is None:
            wrap_angle = getattr(angle, 'wrap_angle', self._default_wrap_angle)
        self.wrap_angle = wrap_angle
        return self

    def __setitem__(self, item, value):
        # Forbid assigning a Lat to a Long.
        if isinstance(value, Latitude):
            raise TypeError("A Latitude angle cannot be assigned to a Longitude angle")
        super().__setitem__(item, value)
        self._wrap_internal()

    def _wrap_internal(self):
        """
        Wrap the internal values in the Longitude object. Using the
        :meth:`~astropy.coordinates.Angle.wrap_at` method causes
        recursion.
        """
        # Convert the wrap angle and 360 degrees to the native unit of
        # this Angle, then do all the math on raw Numpy arrays rather
        # than Quantity objects for speed.
        a360 = u.degree.to(self.unit, 360.0)
        wrap_angle = self.wrap_angle.to_value(self.unit)
        wrap_angle_floor = wrap_angle - a360
        self_angle = self.value
        # Do the wrapping, but only if any angles need to be wrapped
        if np.any(self_angle < wrap_angle_floor) or np.any(self_angle >= wrap_angle):
            wrapped = np.mod(self_angle - wrap_angle, a360) + wrap_angle_floor
            value = u.Quantity(wrapped, self.unit)
            super().__setitem__((), value)

    @property
    def wrap_angle(self):
        return self._wrap_angle

    @wrap_angle.setter
    def wrap_angle(self, value):
        self._wrap_angle = Angle(value, copy=False)
        self._wrap_internal()

    def __array_finalize__(self, obj):
        super().__array_finalize__(obj)
        self._wrap_angle = getattr(obj, '_wrap_angle',
                                   self._default_wrap_angle)

    # Any calculation should drop to Angle
    def __array_ufunc__(self, *args, **kwargs):
        results = super().__array_ufunc__(*args, **kwargs)
        return _no_angle_subclass(results)