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 non-angular 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 :