BaseDifferential¶
-
class
astropy.coordinates.
BaseDifferential
(*args, **kwargs)[source]¶ Bases:
astropy.coordinates.BaseRepresentationOrDifferential
A base class representing differentials of representations.
These represent differences or derivatives along each component. E.g., for physics spherical coordinates, these would be \(\delta r, \delta \theta, \delta \phi\).
- Parameters
- d_comp1, d_comp2, d_comp3
Quantity
or subclass The components of the 3D differentials. The names are the keys and the subclasses the values of the
attr_classes
attribute.- copybool, optional
If
True
(default), arrays will be copied. IfFalse
, arrays will be references, though possibly broadcast to ensure matching shapes.
- d_comp1, d_comp2, d_comp3
Notes
All differential representation classes should subclass this base class, and define an
base_representation
attribute with the class of the regularBaseRepresentation
for which differential coordinates are provided. This will set up a defaultattr_classes
instance with names equal to the base component names prefixed byd_
, and all classes set toQuantity
, plus properties to access those, and a default__init__
for initialization.Methods Summary
from_cartesian
(other, base)Convert the differential from 3D rectangular cartesian coordinates to the desired class.
from_representation
(representation, base)Create a new instance of this representation from another one.
norm
(self[, base])Vector norm.
represent_as
(self, other_class, base)Convert coordinates to another representation.
to_cartesian
(self, base)Convert the differential to 3D rectangular cartesian coordinates.
Methods Documentation
-
classmethod
from_cartesian
(other, base)[source]¶ Convert the differential from 3D rectangular cartesian coordinates to the desired class.
- Parameters
- other :
The object to convert into this differential.
- baseinstance of
self.base_representation
The points for which the differentials are to be converted: each of the components is multiplied by its unit vectors and scale factors.
- Returns
- A new differential object that is this class’ type.
-
classmethod
from_representation
(representation, base)[source]¶ Create a new instance of this representation from another one.
- Parameters
- representation
BaseRepresentation
instance The presentation that should be converted to this class.
- baseinstance of
cls.base_representation
The base relative to which the differentials will be defined. If the representation is a differential itself, the base will be converted to its
base_representation
to help convert it.
- representation
-
norm
(self, base=None)[source]¶ 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.
- Parameters
- baseinstance of
self.base_representation
Base relative to which the differentials are defined. This is required to calculate the physical size of the differential for all but cartesian differentials.
- baseinstance of
- Returns
- norm
astropy.units.Quantity
Vector norm, with the same shape as the representation.
- norm
-
represent_as
(self, other_class, base)[source]¶ 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.
- baseinstance of
self.base_representation
, optional Base relative to which the differentials are defined. If the other class is a differential representation, the base will be converted to its
base_representation
.
- other_class
-
to_cartesian
(self, base)[source]¶ Convert the differential to 3D rectangular cartesian coordinates.
- Parameters
- baseinstance of
self.base_representation
The points for which the differentials are to be converted: each of the components is multiplied by its unit vectors and scale factors.
- baseinstance of
- Returns
- This object as a
CartesianDifferential
- This object as a