Quaternion

Unit quaternions are rotations; the fields are stored exactly as given.

Full docstring

WHY not normalised at construction: a stored property must read back as authored. Every
operation that needs a rotation (`rotate`, `to_matrix`, `multiply`, ...) normalises first;
`normalized()` and `is_unit()` are there when you want the unit value yourself.

Import

from robot_msgs.geometry import Quaternion

ROS 2geometry_msgs/msg/Quaternion

Fields

Name	Type	Default
`x`	`float`	`0.0`
`y`	`float`	`0.0`
`z`	`float`	`0.0`
`w`	`float`	`1.0`

Example

One instance from the package's own test catalog; the output is its real repr().

Quaternion(x=0.034270798550482096, y=0.10602051106179562, z=0.1435721750273919, w=0.9833474432563558)

to_dict() as JSON

{
  "_type": "geometry/Quaternion",
  "x": 0.034270798550482096,
  "y": 0.10602051106179562,
  "z": 0.1435721750273919,
  "w": 0.9833474432563558
}

Long arrays are cut after 16 values and say so with “…”.

Functions

Constructors

Classmethods and staticmethods: ways to build one.

`from_array`

from_array(array: Any) -> Quaternion

No docstring.

`from_axis_angle`

from_axis_angle(axis: Any, angle: float) -> Quaternion

axis need not be unit length, but must be non-zero. Radians.

`from_euler`

from_euler(roll: float, pitch: float, yaw: float) -> Quaternion

ROS RPY: fixed axes X, then Y, then Z (R = Rz·Ry·Rx).

`from_matrix`

from_matrix(matrix: Any) -> Quaternion

From a (3, 3) rotation matrix.

`from_rotvec`

from_rotvec(rotvec: Any) -> Quaternion

From axis × angle (radians).

`from_wxyz`

from_wxyz(array: Any) -> Quaternion

From MuJoCo / viser order.

`identity`

identity() -> Quaternion

No docstring.

`from_dict`

from Msg

from_dict(data: Mapping[str, Any]) -> M

No docstring.

Methods

Return new values; messages are never mutated.

`angle_to`

angle_to(other: Quaternion) -> float

Radians in [0, π] of the rotation that takes self to other.

`as_array`

as_array() -> np.ndarray

(4,) in x, y, z, w order.

`conjugate`

conjugate() -> Quaternion

Negated vector part, fields otherwise as stored.

`inverse`

inverse() -> Quaternion

The unit quaternion of the opposite rotation.

`is_unit`

is_unit(tol: float = 1e-09) -> bool

No docstring.

`multiply`

multiply(other: Quaternion) -> Quaternion

Hamilton product of the unit rotations: apply other first, then self.

`normalized`

normalized() -> Quaternion

No docstring.

`rotate`

rotate(vector: V) -> V

Rotate a Vector3, Point or (..., 3) array; returns the same kind.

`slerp`

slerp(other: Quaternion, alpha: float) -> Quaternion

Along the shorter arc; 0 gives self, 1 gives other, outside [0, 1] extrapolates.

`to_euler`

to_euler() -> tuple[float, float, float]

(roll, pitch, yaw); pitch in [-π/2, π/2].

`to_matrix`

to_matrix() -> np.ndarray

No docstring.

`to_rotvec`

to_rotvec() -> np.ndarray

Axis × angle for the shorter rotation, angle in [0, π].

`to_wxyz`

to_wxyz() -> np.ndarray

No docstring.

`replace`

from Msg

replace(**changes: Any) -> M

A copy with some fields changed. Validation runs again.

`to_dict`

from Msg

to_dict() -> dict[str, Any]

JSON-safe dict with a "_type" key; arrays keep their dtype and shape.

Operators

Python operators and protocols the type supports.

`iter`

__iter__() -> Iterator[float]

No docstring.

`mul`

__mul__(other: object) -> Quaternion

No docstring.

Used by

Types whose fields refer to it.

Pose Transform Imu