Angle

class astropy.coordinates.Angle[source] [edit on github]

Bases: astropy.units.quantity.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, Quantity or another 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 : array, scalar, Quantity, 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 : UnitBase, str, optional

The unit of the value specified for the angle. This may be any string that Unit understands, but it is better to give an actual unit object. Must be an angular unit.

dtype : dtype, optional

See Quantity.

copy : bool, optional

See Quantity.

Raises:

`~astropy.units.UnitsError`

If a unit is not provided or it is not an angular unit.

Attributes Summary

dms The angle’s value in degrees, as a named tuple with (d, m, s) members.
hms The angle’s value in hours, as a named tuple with (h, m, s) members.
hour The angle’s value in hours (read-only property).
signed_dms The angle’s value in degrees, as a named tuple with (sign, d, m, s) members.

Methods Summary

is_within_bounds([lower, upper]) Check if all angle(s) satisfy lower <= angle < upper
to_string([unit, decimal, sep, precision, …]) A string representation of the angle.
wrap_at(wrap_angle[, inplace]) Wrap the Angle object at the given wrap_angle.

Attributes Documentation

dms

The angle’s value in degrees, as a named tuple with (d, m, s) members. (This is a read-only property.)

hms

The angle’s value in hours, as a named tuple with (h, m, s) members. (This is a read-only property.)

hour

The angle’s value in hours (read-only property).

signed_dms

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.

Methods Documentation

is_within_bounds(lower=None, upper=None)[source] [edit on github]

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 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 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

to_string(unit=None, decimal=False, sep='fromunit', precision=None, alwayssign=False, pad=False, fields=3, format=None)[source] [edit on github]

A string representation of the angle.

Parameters:

unit : 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.

wrap_at(wrap_angle, inplace=False)[source] [edit on github]

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  
array([340., 150., 350.])

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

wrap_angle : str, Angle, angular 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.