UnitSphericalRepresentation¶

class
astropy.coordinates.
UnitSphericalRepresentation
(lon, lat, differentials=None, copy=True)[source] [edit on github]¶ Bases:
astropy.coordinates.BaseRepresentation
Representation of points on a unit sphere.
Parameters:  lon, lat :
Quantity
or str The longitude and latitude of the point(s), in angular units. The latitude should be between 90 and 90 degrees, and the longitude will be wrapped to an angle between 0 and 360 degrees. These can also be instances of
Angle
,Longitude
, orLatitude
. differentials : dict,
BaseDifferential
, optional Any differential classes that should be associated with this representation. The input must either be a single
BaseDifferential
instance (see_compatible_differentials
for valid types), or a dictionary of of differential instances with keys set to a string representation of the SI unit with which the differential (derivative) is taken. For example, for a velocity differential on a positional representation, the key would be's'
for seconds, indicating that the derivative is a time derivative. copy : bool, optional
If
True
(default), arrays will be copied rather than referenced.
Attributes Summary
attr_classes
lat
The latitude of the point(s). lon
The longitude of the point(s). Methods Summary
cross
(other)Cross product of two representations. from_cartesian
(cart)Converts 3D rectangular cartesian coordinates to spherical polar coordinates. mean
(*args, **kwargs)Vector mean. norm
()Vector norm. represent_as
(other_class[, differential_class])Convert coordinates to another representation. scale_factors
([omit_coslat])Scale factors for each component’s direction. sum
(*args, **kwargs)Vector sum. to_cartesian
()Converts spherical polar coordinates to 3D rectangular cartesian coordinates. unit_vectors
()Cartesian unit vectors in the direction of each component. Attributes Documentation

attr_classes
= {'lat': <class 'astropy.coordinates.angles.Latitude'>, 'lon': <class 'astropy.coordinates.angles.Longitude'>}¶

lat
¶ The latitude of the point(s).

lon
¶ The longitude of the point(s).
Methods Documentation

cross
(other)[source] [edit on github]¶ Cross product of two representations.
The calculation is done by converting both
self
andother
toCartesianRepresentation
, and converting the result back toSphericalRepresentation
.Parameters:  other : representation
The representation to take the cross product with.
Returns:  cross_product :
SphericalRepresentation
With vectors perpendicular to both
self
andother
.

classmethod
from_cartesian
(cart)[source] [edit on github]¶ Converts 3D rectangular cartesian coordinates to spherical polar coordinates.

mean
(*args, **kwargs)[source] [edit on github]¶ Vector mean.
The representation is converted to cartesian, the means of the x, y, and z components are calculated, and the result is converted to a
SphericalRepresentation
.Refer to
mean
for full documentation of the arguments, noting thataxis
is the entry in theshape
of the representation, and that theout
argument cannot be used.

norm
()[source] [edit on github]¶ Vector norm.
The norm is the standard Frobenius norm, i.e., the square root of the sum of the squares of all components with nonangular units, which is always unity for vectors on the unit sphere.
Returns:  norm :
Quantity
Dimensionless ones, with the same shape as the representation.
 norm :

represent_as
(other_class, differential_class=None)[source] [edit on github]¶ Convert coordinates to another representation.
If the instance is of the requested class, it is returned unmodified. By default, conversion is done via cartesian coordinates.
Parameters:  other_class :
BaseRepresentation
subclass The type of representation to turn the coordinates into.
 differential_class : dict of
BaseDifferential
, optional Classes in which the differentials should be represented. Can be a single class if only a single differential is attached, otherwise it should be a
dict
keyed by the same keys as the differentials.
 other_class :

scale_factors
(omit_coslat=False)[source] [edit on github]¶ Scale factors for each component’s direction.
Given unit vectors \(\hat{e}_c\) and scale factors \(f_c\), a change in one component of \(\delta c\) corresponds to a change in representation of \(\delta c \times f_c \times \hat{e}_c\).
Returns:  scale_factors : dict of
Quantity
The keys are the component names.
 scale_factors : dict of

sum
(*args, **kwargs)[source] [edit on github]¶ Vector sum.
The representation is converted to cartesian, the sums of the x, y, and z components are calculated, and the result is converted to a
SphericalRepresentation
.Refer to
sum
for full documentation of the arguments, noting thataxis
is the entry in theshape
of the representation, and that theout
argument cannot be used.

to_cartesian
()[source] [edit on github]¶ Converts spherical polar coordinates to 3D rectangular cartesian coordinates.

unit_vectors
()[source] [edit on github]¶ Cartesian unit vectors in the direction of each component.
Given unit vectors \(\hat{e}_c\) and scale factors \(f_c\), a change in one component of \(\delta c\) corresponds to a change in representation of \(\delta c \times f_c \times \hat{e}_c\).
Returns:  unit_vectors : dict of
CartesianRepresentation
The keys are the component names.
 unit_vectors : dict of
 lon, lat :