AttitudeRepresentation

class erwans3.Telescope_class.AttitudeRepresentation(x: Union[ndarray, Rotation, AttitudeRepresentation], y: Optional[ndarray] = None, z: Optional[ndarray] = None, w: Optional[ndarray] = None, xyzw_axis: int = -1, differentials: Optional[BaseDifferential] = None, copy: bool = True)

Bases: BaseRepresentation

Represents attitude information in terms of quaternion.

This class inherits from BaseRepresentation and provides functionality to represent attitude information using quaternions or rotations. However, that representation is not a coordinate representation It cannot be converted with cartesian representation which limit its uses.

Parameters:

x (ndarray or Rotation or AttitudeRepresentation) – If a single argument is provided, it can be: - AttitudeRepresentation: Initialize from another AttitudeRepresentation instance. - Rotation: Initialize from a Rotation instance. - ndarray: Initialize from a quaternion array or a rotation vector array.
y (ndarray, optional) – Second component of the quaternion (if provided).
z (ndarray, optional) – Third component of the quaternion (if provided).
w (ndarray, optional) – Fourth component of the quaternion (if provided).
xyzw_axis (int, optional) – Axis along which the xyzw components are defined. Default is -1.
differentials (dict, optional) – Dictionary containing differential attributes. Default is None.
copy (bool, optional) – If True, performs a deep copy of input arrays. Default is True.

attr_classes

Dictionary defining the attribute classes for x, y, z, w components.

Type:: dict

_q

Internal representation of the quaternion.

Type:: ndarray or None

_differentials

Dictionary containing differential attributes.

Type:: dict

Notes

AttitudeRepresentation object main usage is to be encapsulated in a |SatCoord| object Thus it can associated to a frame and frame transformation can be performed.

Usage: >>> att = AttitudeRepresentation(0,0,0,1) >>> coord = ICRS(CartesianRepresentation(np.ones(3)*u.m)) >>> sat_icrs = SatCoord(coord, att, obstime=Time.now()) >>> sat_gcrs = sat_icrs.transform_to(GCRS) >>> print(sat_gcrs.att)

Yet, AttitudeRepresentation can be attached to a frame on its own. >>> att = AttitudeRepresentation(0,0,0,1) >>> att_frame = ICRS(att) Frame transformation can be applied as long as no FunctionTransform or FunctionTransformWithFiniteDifference are not involve example: >>> att_hcrs = HCSR(AttitudeRepresentation.make_random(), representation_type=AttitudeRepresentation) >>> att_sg = att_hcrs.transform_to(Supergalactic(representation_type=AttitudeRepresentation)) Frames defined with |Frame_class.CustomFrame| uses Affine transform and thus can be used to transform AttitudeRepresentation

See also

BaseRepresentation: Base class for representations.
Rotation: Class representing rotations in astropy.coordinates.

Attributes Summary

`attr_classes`
`q`	Get the quaternion representation of the AttitudeRepresentation.
`rot`	Get the Rotation instance from the quaternion representation.
`w`	The 'w' component of the points(s).
`x`	The 'x' component of the points(s).
`y`	The 'y' component of the points(s).
`z`	The 'z' component of the points(s).

Methods Summary

`from_cartesian`(cart)	should not be used !
`from_matrix`(mats)	Create an `AttitudeRepresentation` instance from rotation matrices.
`get_q`()	Get the quaternion representation of the AttitudeRepresentation.
`make_identity`(rotshape)	Create an identity AttitudeRepresentation instance.
`make_random`(rotshape)	Create a random `AttitudeRepresentation` instance.
`to_cartesian`()	should not be used !
`transform`(matrix)	Transform the AttitudeRepresentation by a rotation matrix.

Attributes Documentation

attr_classes = {'w': <class 'astropy.units.quantity.Quantity'>, 'x': <class 'astropy.units.quantity.Quantity'>, 'y': <class 'astropy.units.quantity.Quantity'>, 'z': <class 'astropy.units.quantity.Quantity'>}

q

Get the quaternion representation of the AttitudeRepresentation.

This property returns the quaternion representation of the AttitudeRepresentation instance. If the internal _q attribute is set, it returns _q. Otherwise, it constructs the quaternion array using the _x, _y, _z, and _w components.

Returns:: Quaternion representation of the AttitudeRepresentation.
Return type:: ndarray

rot

Get the Rotation instance from the quaternion representation.

This property returns a Rotation instance derived from the quaternion representation of the AttitudeRepresentation instance. It uses the quaternion array _q to construct the Rotation instance.

Returns:: Rotation instance corresponding to the quaternion representation.
Return type:: Rotation

Notes

If the quaternion array _q has a dimension less than or equal to 1, it constructs a

Rotation instance using Rotation.from_quat. - If _q has a dimension greater than 1, it constructs a Rotation instance using get_rot_from_quat_vec.

w: The ‘w’ component of the points(s).

x: The ‘x’ component of the points(s).

y: The ‘y’ component of the points(s).

z: The ‘z’ component of the points(s).

Methods Documentation

classmethod from_cartesian(cart): should not be used !

classmethod from_matrix(mats) → AttitudeRepresentation

Create an AttitudeRepresentation instance from rotation matrices.

This class method creates an AttitudeRepresentation instance from rotation matrices. It extracts quaternion representations from the input rotation matrices mats.

Parameters:: mats (ndarray) – Rotation matrices from which to create the AttitudeRepresentation instance.
Returns:: AttitudeRepresentation instance created from the input rotation matrices.
Return type:: AttitudeRepresentation

Notes

This class method extracts quaternion representations from rotation matrices to create

an AttitudeRepresentation instance. - The input mats should be compatible with the conversion to quaternions.

Examples

>>> # Assuming `mats` is an array of rotation matrices
>>> att_rep = AttitudeRepresentation.from_matrix(mats)
>>> print(att_rep)
AttitudeRepresentation([x, y, z, w])  # Example output with quaternion components

get_q() → ndarray

Get the quaternion representation of the AttitudeRepresentation.

This property returns the quaternion representation of the AttitudeRepresentation instance. If the internal _q attribute is set, it returns _q. Otherwise, it constructs the quaternion array using the _x, _y, _z, and _w components.

Returns:: Quaternion representation of the AttitudeRepresentation.
Return type:: ndarray

classmethod make_identity(rotshape) → AttitudeRepresentation

Create an identity AttitudeRepresentation instance.

This class method creates an identity AttitudeRepresentation instance with the specified shape based on the input rotshape. The identity representation corresponds to a quaternion array representing no rotation (all components equal to [1, 0, 0, 0]).

Parameters:: rotshape (int or tuple) – Shape of the identity representation. If an integer is provided, a 1D identity representation is created. If a tuple is provided, it specifies the shape of the identity representation array.
Returns:: Identity AttitudeRepresentation instance with the specified shape.
Return type:: AttitudeRepresentation
Raises:: TypeError – If the input type for rotshape is not supported (should be a tuple or an integer).

Notes

This class method creates an identity AttitudeRepresentation instance with all quaternion components

set to [1, 0, 0, 0], representing no rotation. - The shape of the identity representation determines the size of the identity array.

classmethod make_random(rotshape) → AttitudeRepresentation

Create a random AttitudeRepresentation instance.

This class method creates a random AttitudeRepresentation instance with the specified shape based on the input rotshape. The random representation corresponds to a quaternion array representing a random rotation.

Parameters:: rotshape (int or tuple) – Shape of the random representation. If an integer is provided, a 1D random representation is created. If a tuple is provided, it specifies the shape of the random representation array.
Returns:: Random AttitudeRepresentation instance with the specified shape.
Return type:: AttitudeRepresentation

Notes

This class method creates a random AttitudeRepresentation instance with quaternion components

representing a random rotation. - The shape of the random representation determines the size of the random array.

to_cartesian()

should not be used !

returns itself in order to compute some frame transorm

transform(matrix: ndarray) → AttitudeRepresentation

Transform the AttitudeRepresentation by a rotation matrix.

This method transforms the AttitudeRepresentation instance by applying a rotation represented by the input rotation matrix matrix. The transformation is performed by first creating a new AttitudeRepresentation from the rotation matrix, then applying the rotation to the current AttitudeRepresentation.

Parameters:: matrix (ndarray) – Rotation matrix representing the transformation.
Returns:: Transformed AttitudeRepresentation instance after applying the rotation.
Return type:: AttitudeRepresentation

Notes

The transformation is performed by creating a new AttitudeRepresentation instance from

the rotation matrix and then applying it to the current AttitudeRepresentation. - The order of transformation (whether the input matrix is applied first or last) depends on the specific implementation of the from_matrix method and the multiplication logic.