SO(3) matrix
- class SO3(*args, **kwargs)[source]
Bases:
BasePoseMatrix
SO(3) matrix class
This subclass represents rotations in 3D space. Internally it is a 3x3 orthogonal matrix belonging to the group SO(3).
- classmethod Alloc(n=1)
Construct an instance with N default values (BasePoseList superclass method)
- Parameters:
n (int, optional) – Number of values, defaults to 1
- Return type:
Self
- Returns:
pose instance with
n
default values
X.Alloc(N)
creates an instance of the pose classX
withN
default values, ie.len(X)
will beN
.X
can be considered a vector of pose objects, and those elements can be referencedX[i]
or assigned toX[i] = ...
.Note
The default value depends on the pose class and is the result of the empty constructor. For
SO2
,SE2
,SO3
,SE3
it is an identity matrix, for a twist classTwist2
orTwist3
it is a zero vector, for aUnitQuaternion
orQuaternion
it is a zero vector.Example:
>>> x = X.Alloc(10) >>> len(x) 10
where
X
is any of the SMTB classes.
- classmethod AngVec(theta, v, *, unit='rad')[source]
Construct a new SO(3) rotation matrix from rotation angle and axis
- Parameters:
theta (float) – rotation
unit (str) – angular units: ‘rad’ [default], or ‘deg’
v (array_like) – rotation axis, 3-vector
- Returns:
SO(3) rotation
- Return type:
SO3 instance
SO3.AngVec(theta, V)
is an SO(3) rotation defined by a rotation ofTHETA
about the vectorV
.Deprecated since version 0.9.8: Use
AngleAxis()
instead.
- classmethod AngleAxis(theta, v, *, unit='rad')[source]
Construct a new SO(3) rotation matrix from rotation angle and axis
- Parameters:
theta (float) – rotation
unit (str) – angular units: ‘rad’ [default], or ‘deg’
v (array_like) – rotation axis, 3-vector
- Returns:
SO(3) rotation
- Return type:
SO3 instance
SO3.AngleAxis(theta, V)
is an SO(3) rotation defined by a rotation ofTHETA
about the vectorV
.Note
\(\theta \eq 0\) the result in an identity matrix, otherwise
V
must have a finite length, ie. \(|V| > 0\).
- classmethod Empty()
Construct an empty instance (BasePoseList superclass method)
- Return type:
Self
- Returns:
pose instance with zero values
Example:
>>> x = X.Empty() >>> len(x) 0
where
X
is any of the SMTB classes.
- classmethod Eul(*angles, unit='rad')[source]
Construct a new SO(3) from Euler angles
- Parameters:
𝚪 (3 floats, array_like(3) or ndarray(N,3)) – Euler angles
unit (str) – angular units: ‘rad’ [default], or ‘deg’
- Returns:
SO(3) rotation
- Return type:
SO3 instance
SO3.Eul(𝚪)
is an SO(3) rotation defined by a 3-vector of Eulerangles \(\Gamma = (\phi, \theta, \psi)\) which correspond to consecutive rotations about the Z, Y, Z axes respectively. If
𝚪
is an Nx3 matrix then the result is a sequence of rotations each defined by Euler angles corresponding to the rows ofangles
.SO3.Eul(φ, θ, ψ)
as above but the angles are provided as threescalars.
Example:
>>> from spatialmath import SO3 >>> SO3.Eul(0.1, 0.2, 0.3) SO3(array([[ 0.9021, -0.3836, 0.1977], [ 0.3875, 0.9216, 0.0198], [-0.1898, 0.0587, 0.9801]])) >>> SO3.Eul([0.1, 0.2, 0.3]) SO3(array([[ 0.9021, -0.3836, 0.1977], [ 0.3875, 0.9216, 0.0198], [-0.1898, 0.0587, 0.9801]])) >>> SO3.Eul(10, 20, 30, unit="deg") SO3(array([[ 0.7146, -0.6131, 0.3368], [ 0.6337, 0.7713, 0.0594], [-0.2962, 0.171 , 0.9397]]))
- classmethod EulerVec(w)[source]
Construct a new SO(3) rotation matrix from an Euler rotation vector
- Parameters:
ω (3-element array_like) – rotation axis
- Returns:
SO(3) rotation
- Return type:
SO3 instance
SO3.EulerVec(ω)
is a unit quaternion that describes the 3D rotation defined by a rotation of \(\theta = \lVert \omega \rVert\) about the unit 3-vector \(\omega / \lVert \omega \rVert\).Example:
>>> from spatialmath import SO3 >>> SO3.EulerVec([0.5,0,0]) SO3(array([[ 1. , 0. , 0. ], [ 0. , 0.8776, -0.4794], [ 0. , 0.4794, 0.8776]]))
Note
\(\theta \eq 0\) the result in an identity matrix, otherwise
V
must have a finite length, ie. \(|V| > 0\).- Seealso:
- classmethod Exp(S, check=True, so3=True)[source]
Create an SO(3) rotation matrix from so(3)
- Parameters:
S (ndarray(3,3), ndarray(n,3)) – Lie algebra so(3)
check (
bool
) – check that passed matrix is valid so(3), default Trueso3 (
bool
) – the input is interpretted as an so(3) matrix not a stack of three twists, default True
- Bool check:
bool, optional
- Returns:
SO(3) rotation
- Return type:
SO3 instance
SO3.Exp(S)
is an SO(3) rotation defined by its Lie algebra which is a 3x3 so(3) matrix (skew symmetric)SO3.Exp(t)
is an SO(3) rotation defined by a 3-element twist vector (the unique elements of the so(3) skew-symmetric matrix)SO3.Exp(T)
is a sequence of SO(3) rotations defined by an Nx3 matrix of twist vectors, one per row.
if \(\theta \eq 0\) the result in an identity matrix
an input 3x3 matrix is ambiguous, it could be the first or third case above. In this case the parameter so3 is the decider.
- classmethod OA(o, a)[source]
Construct a new SO(3) from two vectors
- Parameters:
- Returns:
SO(3) rotation
- Return type:
SO3 instance
SO3.OA(O, A)
is an SO(3) rotation defined in terms of vectors parallel to the Y- and Z-axes of its reference frame. In robotics these axes are respectively called the orientation and approach vectors defined such that R = [N, O, A] and N = O x A.Note
Only the
A
vector is guaranteed to have the same direction in the resulting
rotation matrix -
O
andA
do not have to be unit-length, they are normalized -O
and ``A` do not have to be orthogonal, so long as they are not parallel- Seealso:
- classmethod RPY(*angles, unit='rad', order='zyx')[source]
Construct a new SO(3) from roll-pitch-yaw angles
- Parameters:
angles (array_like(3), array_like(n,3)) – roll-pitch-yaw angles
unit (str) – angular units: ‘rad’ [default], or ‘deg’
order (str) – rotation order: ‘zyx’ [default], ‘xyz’, or ‘yxz’
- Returns:
SO(3) rotation
- Return type:
SO3 instance
SO3.RPY(angles)
is an SO(3) rotation defined by a 3-vector of roll, pitch, yaw angles \((\alpha, \beta, \gamma)\). Ifangles
is an Nx3 matrix then the result is a sequence of rotations each defined by RPY angles corresponding to the rows of angles. The angles correspond to successive rotations about the axes specified byorder
:'zyx'
[default], rotate by yaw about the z-axis, then by pitch about the new y-axis, then by roll about the new x-axis. Convention for a mobile robot with x-axis forward and y-axis sideways.
'xyz'
, rotate by yaw about the x-axis, then by pitch about the new y-axis, then by roll about the new z-axis. Convention for a robot gripper with z-axis forward and y-axis between the gripper fingers.'yxz'
, rotate by yaw about the y-axis, then by pitch about the new x-axis, then by roll about the new z-axis. Convention for a camera with z-axis parallel to the optic axis and x-axis parallel to the pixel rows.
SO3.RPY(⍺, β, 𝛾)
as above but the angles are provided as three scalars.
Example:
>>> from spatialmath import SO3 >>> SO3.RPY(0.1, 0.2, 0.3) SO3(array([[ 0.9363, -0.2751, 0.2184], [ 0.2896, 0.9564, -0.037 ], [-0.1987, 0.0978, 0.9752]])) >>> SO3.RPY([0.1, 0.2, 0.3]) SO3(array([[ 0.9363, -0.2751, 0.2184], [ 0.2896, 0.9564, -0.037 ], [-0.1987, 0.0978, 0.9752]])) >>> SO3.RPY(0.1, 0.2, 0.3, order='xyz') SO3(array([[ 0.9752, -0.0978, 0.1987], [ 0.1538, 0.9447, -0.2896], [-0.1593, 0.313 , 0.9363]])) >>> SO3.RPY(10, 20, 30, unit="deg") SO3(array([[ 0.8138, -0.441 , 0.3785], [ 0.4698, 0.8826, 0.018 ], [-0.342 , 0.1632, 0.9254]]))
- Seealso:
- classmethod Rand(N=1, *, theta_range=None, unit='rad')[source]
Construct a new SO(3) from random rotation
- Parameters:
- Returns:
SO(3) rotation matrix
- Return type:
SO3 instance
SO3.Rand()
is a random SO(3) rotation.SO3.Rand(N)
is a sequence of N random rotations.
Example:
>>> from spatialmath import SO3 >>> x = SO3.Rand() >>> x SO3(array([[-0.7756, -0.5699, -0.2715], [ 0.3374, -0.0106, -0.9413], [ 0.5336, -0.8216, 0.2005]]))
- classmethod RotatedVector(v1, v2, tol=20)[source]
Construct a new SO(3) from a vector and its rotated image
- Parameters:
v1 (array_like(3)) – initial vector
v2 (array_like(3)) – vector after rotation
tol (float) – tolerance for singularity in units of eps, defaults to 20
- Returns:
SO(3) rotation
- Return type:
SO3
instance
SO3.RotatedVector(v1, v2)
is an SO(3) rotation defined in terms of two vectors. The rotation takes vectorv1
tov2
.>>> from spatialmath import SO3 >>> v1 = [1, 2, 3] >>> v2 = SO3.Eul(0.3, 0.4, 0.5) * v1 >>> print(v2) [[0.3842] [2.4579] [2.7948]] >>> R = SO3.RotatedVector(v1, v2) >>> print(R) 0.9857 -0.1131 -0.1251 0.1282 0.9844 0.1203 0.1095 -0.1346 0.9848 >>> print(R * v1) [[0.3842] [2.4579] [2.7948]]
Note
The vectors do not have to be unit-length.
- classmethod Rx(theta, unit='rad')[source]
Construct a new SO(3) from X-axis rotation
- Parameters:
θ (float or array_like) – rotation angle about the X-axis
unit (str) – angular units: ‘rad’ [default], or ‘deg’
- Returns:
SO(3) rotation
- Return type:
SO3 instance
SE3.Rx(θ)
is an SO(3) rotation ofθ
radians about the x-axisSE3.Rx(θ, "deg")
as above butθ
is in degrees
If
theta
is an array then the result is a sequence of rotations defined by consecutive elements.Example:
File "<input>", line 1, in <module> NameError: name 'x' is not defined Traceback (most recent call last): File "<input>", line 1, in <module> NameError: name 'x' is not defined
- classmethod Ry(theta, unit='rad')[source]
Construct a new SO(3) from Y-axis rotation
- Parameters:
θ (float or array_like) – rotation angle about Y-axis
unit (str) – angular units: ‘rad’ [default], or ‘deg’
- Returns:
SO(3) rotation
- Return type:
SO3 instance
SO3.Ry(θ)
is an SO(3) rotation ofθ
radians about the y-axisSO3.Ry(θ, "deg")
as above butθ
is in degrees
If
θ
is an array then the result is a sequence of rotations defined by consecutive elements.Example:
File "<input>", line 1, in <module> NameError: name 'x' is not defined Traceback (most recent call last): File "<input>", line 1, in <module> NameError: name 'x' is not defined
- classmethod Rz(theta, unit='rad')[source]
Construct a new SO(3) from Z-axis rotation
- Parameters:
θ (float or array_like) – rotation angle about Z-axis
unit (str) – angular units: ‘rad’ [default], or ‘deg’
- Returns:
SO(3) rotation
- Return type:
SO3 instance
SO3.Rz(θ)
is an SO(3) rotation ofθ
radians about the z-axisSO3.Rz(θ, "deg")
as above butθ
is in degrees
If
θ
is an array then the result is a sequence of rotations defined by consecutive elements.Example:
File "<input>", line 1, in <module> NameError: name 'x' is not defined Traceback (most recent call last): File "<input>", line 1, in <module> NameError: name 'x' is not defined
- classmethod TwoVectors(x=None, y=None, z=None)[source]
Construct a new SO(3) from any two vectors
- Parameters:
x (str, array_like(3), optional) – new x-axis, defaults to None
y (str, array_like(3), optional) – new y-axis, defaults to None
z (str, array_like(3), optional) – new z-axis, defaults to None
- Return type:
Self
Create a rotation by defining the direction of two of the new axes in terms of the old axes. Axes are denoted by strings
"x"
,"y"
,"z"
,"-x"
,"-y"
,"-z"
.The directions can also be specified by 3-element vectors. If the vectors are not orthogonal, they will orthogonalized w.r.t. the first available dimension. I.e. if x is available, it will be normalized and the remaining vector will be orthogonalized w.r.t. x, else, y will be normalized and z will be orthogonalized w.r.t. y.
To create a rotation where the new frame has its x-axis in -z-direction of the previous frame, and its z-axis in the x-direction of the previous frame is:
>>> SO3.TwoVectors(x='-z', z='x')
- UnitQuaternion()[source]
SO3 as a unit quaternion instance
- Returns:
a unit quaternion representation
- Return type:
UnitQuaternion instance
R.UnitQuaternion()
is anUnitQuaternion
instance representing the same rotation as the SO3 rotationR
.Example:
>>> from spatialmath import SO3 >>> SO3.Rz(0.3).UnitQuaternion() UnitQuaternion(array([0.9888, 0. , 0. , 0.1494]))
- __add__(right)
Overloaded
+
operator (superclass method)- Returns:
Sum of two operands
- Return type:
NumPy array, shape=(N,N)
- Raises:
ValueError – for incompatible arguments
Add the elements of two poses. This is not a group operation so the result is a matrix not a pose class.
X + Y
is the element-wise sum of the matrix value ofX
andY
X + s
is the element-wise sum of the matrix value ofX
and scalars
s + X
is the element-wise sum of the scalars
and the matrix value ofX
Operands
Sum
left
right
type
operation
Pose
Pose
NxN matrix
element-wise matrix sum
Pose
scalar
NxN matrix
element-wise sum
scalar
Pose
NxN matrix
element-wise sum
Note
Pose is an
SO2
,SE2
,SO3
orSE3
instanceN is 2 for
SO2
,SE2
; 3 forSO3
orSE3
scalar + Pose is handled by
__radd__()
Addition is commutative
Any other input combinations result in a
ValueError
.
For pose addition either or both operands may hold more than one value which results in the sum holding more than one value according to:
len(left)
len(right)
len
operation
1
1
1
sum = left + right
1
M
M
sum[i] = left + right[i]
N
1
M
sum[i] = left[i] + right
M
M
M
sum[i] = left[i] + right[i]
- __eq__(right)
Overloaded
==
operator (superclass method)- Returns:
Equality of two operands
- Return type:
bool or list of bool
Test two poses for equality
X == Y
is true of the poses are of the same type and numerically equal.If either or both operands may hold more than one value which results in the equality test holding more than one value according to:
len(left)
len(right)
len
operation
1
1
1
eq = left == right
1
M
M
eq[i] = left == right[i]
N
1
M
eq[i] = left[i] == right
M
M
M
eq[i] = left[i] == right[i]
- __init__(arg=None, *, check=True)[source]
Construct new SO(3) object
- Return type:
SO3 instance
There are multiple call signatures:
SO3()
is anSO3
instance with one value – a 3x3 identity matrix which corresponds to a null rotationSO3(R)
is anSO3
instance with with the valueR
which is a 3x3 numpy array representing an SO(3) rotation matrix. Ifcheck
isTrue
check the matrix belongs to SO(3).SO3([R1, R2, ... RN])
is anSO3
instance wwithN
values given by the elementsRi
each of which is a 3x3 NumPy array representing an SO(3) matrix. Ifcheck
isTrue
check the matrix belongs to SO(3).SO3([X1, X2, ... XN])
is anSO3
instance withN
values given by the elementsXi
each of which is an SO3 or SE3 instance.
- SymPy:
supported
- __mul__(right)
Overloaded
*
operator (superclass method)- Returns:
Product of two operands
- Return type:
Pose instance or NumPy array
- Raises:
NotImplemented – for incompatible arguments
Pose composition, scaling or vector transformation:
X * Y
compounds the posesX
andY
X * s
performs element-wise multiplication of the elements ofX
bys
s * X
performs element-wise multiplication of the elements ofX
bys
X * v
linear transformation of the vectorv
wherev
is array-like
Multiplicands
Product
left
right
type
operation
Pose
Pose
Pose
matrix product
Pose
scalar
NxN matrix
element-wise product
scalar
Pose
NxN matrix
element-wise product
Pose
N-vector
N-vector
vector transform
Pose
NxM matrix
NxM matrix
transform each column
Note
Pose is an
SO2
,SE2
,SO3
orSE3
instanceN is 2 for
SO2
,SE2
; 3 forSO3
orSE3
Scalar x Pose is handled by __rmul__`
Scalar multiplication is commutative but the result is not a group operation so the result will be a matrix
Any other input combinations result in a ValueError.
For pose composition either or both operands may hold more than one value which results in the composition holding more than one value according to:
len(left)
len(right)
len
operation
1
1
1
prod = left * right
1
M
M
prod[i] = left * right[i]
N
1
M
prod[i] = left[i] * right
M
M
M
prod[i] = left[i] * right[i]
Example:
>>> SE3.Rx(pi/2) * SE3.Ry(pi/2) SE3(array([[0., 0., 1., 0.], [1., 0., 0., 0.], [0., 1., 0., 0.], [0., 0., 0., 1.]])) >>> SE3.Rx(pi/2) * 2 array([[ 2.0000000e+00, 0.0000000e+00, 0.0000000e+00, 0.0000000e+00], [ 0.0000000e+00, 1.2246468e-16, -2.0000000e+00, 0.0000000e+00], [ 0.0000000e+00, 2.0000000e+00, 1.2246468e-16, 0.0000000e+00], [ 0.0000000e+00, 0.0000000e+00, 0.0000000e+00, 2.0000000e+00]])
For vector transformation there are three cases:
Multiplicands
Product
len(left)
right.shape
shape
operation
1
(N,)
(N,)
vector transformation
M
(N,)
(N,M)
vector transformations
1
(N,M)
(N,M)
column transformation
Note
The vector is an array-like, a 1D NumPy array or a list/tuple
For the
SE2
andSE3
case the vectors are converted to homogeneous form, transformed, then converted back to Euclidean form.
Example:
>>> SE3.Rx(pi/2) * [0, 1, 0] array([0.000000e+00, 6.123234e-17, 1.000000e+00]) >>> SE3.Rx(pi/2) * np.r_[0, 0, 1] array([ 0.000000e+00, -1.000000e+00, 6.123234e-17])
- __ne__(right)
Overloaded
!=
operator (superclass method)- Returns:
Inequality of two operands
- Return type:
bool or list of bool
Test two poses for inequality
X != Y
is true of the poses are of the same type but not numerically equal.
If either or both operands may hold more than one value which results in the inequality test holding more than one value according to:
len(left)
len(right)
len
operation
1
1
1
ne = left != right
1
M
M
ne[i] = left != right[i]
N
1
M
ne[i] = left[i] != right
M
M
M
ne[i] = left[i] != right[i]
- __pow__(n)
Overloaded
**
operator (superclass method)- Parameters:
n (int) – exponent
- Returns:
pose to the power
n
- Return type:
pose instance
X**n
raise all values held in X to the specified power using repeated multiplication. Ifn
< 0 then the result is inverted.Example:
>>> from spatialmath import SE3 >>> SE3.Rx(0.1) ** 2 SE3(array([[ 1. , 0. , 0. , 0. ], [ 0. , 0.9801, -0.1987, 0. ], [ 0. , 0.1987, 0.9801, 0. ], [ 0. , 0. , 0. , 1. ]])) >>> SE3.Rx([0, 0.1]) ** 2 SE3([ array([[1., 0., 0., 0.], [0., 1., 0., 0.], [0., 0., 1., 0.], [0., 0., 0., 1.]]), array([[ 1. , 0. , 0. , 0. ], [ 0. , 0.9801, -0.1987, 0. ], [ 0. , 0.1987, 0.9801, 0. ], [ 0. , 0. , 0. , 1. ]]) ])
- __sub__(right)
Overloaded
-
operator (superclass method)- Returns:
Difference of two operands
- Return type:
NumPy array, shape=(N,N)
- Raises:
ValueError – for incompatible arguments
Subtract elements of two poses. This is not a group operation so the result is a matrix not a pose class.
X - Y
is the element-wise difference of the matrix value ofX
andY
X - s
is the element-wise difference of the matrix value ofX
and the scalars
s - X
is the element-wise difference of the scalars
and the matrix value ofX
Operands
Sum
left
right
type
operation
Pose
Pose
NxN matrix
element-wise matrix difference
Pose
scalar
NxN matrix
element-wise sum
scalar
Pose
NxN matrix
element-wise sum
Note
Pose is
SO2
,SE2
,SO3
orSE3
instanceN is 2 for
SO2
,SE2
; 3 forSO3
orSE3
scalar - Pose is handled by
__rsub__()
Any other input combinations result in a
ValueError
.
For pose subtraction either or both operands may hold more than one value which results in the difference holding more than one value according to:
len(left)
len(right)
len
operation
1
1
1
diff = left - right
1
M
M
diff[i] = left - right[i]
N
1
M
diff[i] = left[i] - right
M
M
M
diff[i] = left[i] right[i]
- __truediv__(right)
Overloaded
/
operator (superclass method)- Returns:
Product of right operand and inverse of left operand
- Return type:
pose instance or NumPy array
- Raises:
ValueError – for incompatible arguments
Pose composition or scaling:
X / Y
compounds the posesX
andY.inv()
X / s
performs elementwise division of the elements ofX
bys
Multiplicands
Quotient
left
right
type
operation
Pose
Pose
Pose
matrix product by inverse
Pose
scalar
NxN matrix
element-wise division
Note
Pose is
SO2
,SE2
,SO3
orSE3
instanceN is 2 for
SO2
,SE2
; 3 forSO3
orSE3
Scalar multiplication is not a group operation so the result will be a matrix
Any other input combinations result in a ValueError.
For pose composition either or both operands may hold more than one value which results in the composition holding more than one value according to:
len(left)
len(right)
len
operation
1
1
1
quo = left * right.inv()
1
M
M
quo[i] = left * right[i].inv()
N
1
M
quo[i] = left[i] * right.inv()
M
M
M
quo[i] = left[i] * right[i].inv()
- angdist(other, metric=6)[source]
Angular distance metric between rotations
- Parameters:
other (SO3 instance) – second rotation
metric (int) – metric, default is 6
- Raises:
TypeError – if other is not an SO3
- Returns:
angle in radians
- Return type:
float or ndarray
R1.angdist(R2)
is the geodesic norm, or geodesic distance between two rotations.Several metrics are supported, the first 5 are computed after conversion to unit quaternions.
Metric
Details
0
\(1 - | \q_1 \bullet \q_2 | \in [0, 1]\)
1
\(\cos^{-1} | \q_1 \bullet \q_2 | \in [0, \pi/2]\)
2
\(\cos^{-1} | \q_1 \bullet \q_2 | \in [0, \pi/2]\)
3
\(2 \tan^{-1} \| \q_1 - \q_2\| / \|\q_1 + \q_2\| \in [0, \pi/2]\)
4
\(\cos^{-1} \left( 2 (\q_1 \bullet \q_2)^2 - 1\right) \in [0, 1]\)
5
\(\|I - \mat{R}_1 \mat{R}_2^T\| \in [0, 2]\)
6
\(\|\log \mat{R}_1 \mat{R}_2^T\| \in [0, \pi]\)
Example:
>>> from spatialmath import SO3 >>> R1 = SO3.Rx(0.3) >>> R2 = SO3.Ry(0.3) >>> print(R1.angdist(R1)) 0.0 >>> print(R1.angdist(R2)) 0.4234654354756045
Note
metrics 1, 2, 4 can throw ValueError “math domain error” due to numeric errors which push the argument of
acos()
marginally outside its domain [0, 1].metrics 2 and 3 are equivalent, but 3 is more robust
- Seealso:
UnitQuaternion.angdist()
- angvec(unit='rad')[source]
SO(3) or SE(3) as angle and rotation vector
- Parameters:
unit (str) – angular units: ‘rad’ [default], or ‘deg’
- Returns:
\((\theta, \hat{\bf v})\)
- Return type:
float or ndarray(3)
x.angvec()
is a tuple \((\theta, v)\) containing the rotation angle and a rotation axis.By default the angle is in radians but can be changed setting unit=’deg’.
Note
If the input is SE(3) the translation component is ignored.
Example:
>>> from spatialmath import SO3 >>> R = SO3.Rx(0.3) >>> R.angvec() (0.3, array([1., 0., 0.]))
- Seealso:
eulervec()
AngVec()
angvec()
AngVec()
,angvec2r()
- animate(*args, start=None, **kwargs)
Plot pose object as an animated coordinate frame (superclass method)
- Parameters:
start (same as
self
) – initial pose, defaults to null/identity**kwargs – plotting options
- Return type:
None
X.animate()
displays the poseX
as a coordinate frame moving from the origin in either 2D or 3D. There are many options, see the links below.X.animate(*args, start=X1)
displays the poseX
as a coordinate frame moving from poseX1
, in either 2D or 3D. There are many options, see the links below.
Example:
>>> X = SE3.Rx(0.3) >>> X.animate(frame='A', color='green') >>> X.animate(start=SE3.Ry(0.2))
- Seealso:
- append(item)
Append a value to an instance (BasePoseList superclass method)
- Parameters:
x (Quaternion or UnitQuaternion instance) – the value to append
- Raises:
ValueError – incorrect type of appended object
- Return type:
None
Appends the argument to the object’s internal list of values.
Example:
>>> x = X.Alloc(10) >>> len(x) 10 >>> x.append(X()) # append to the list >>> len(x) 11
where
X
is any of the SMTB classes.
- arghandler(arg, convertfrom=(), check=True)
Standard constructor support (BasePoseList superclass method)
- Parameters:
arg (
Any
) – initial valueconvertfrom (
Tuple
) – list of classes to accept and convert fromcheck (bool) – check value is valid, defaults to True
- Type:
tuple of typles
- Raises:
ValueError – bad type passed
- Return type:
bool
The value
arg
can be any of:None, an identity value is created
a numpy.ndarray of the appropriate shape and value which is valid for the subclass
a list whose elements all meet the criteria above
an instance of the subclass
a list whose elements are all singelton instances of the subclass
For cases 2 and 3, a NumPy array or a list of NumPy array is passed. Each NumPyarray is tested for validity (if
check
is False a cursory check of shape is made, ifcheck
is True the numerical value is inspected) and converted to the required internal format by the_import
method. The default_import
method calls theisvalid
method for checking. This mechanism allows equivalent forms to be passed, ie. 6x1 or 4x4 for an se(3).If
self
is an instance of classA
, and an instance of classB
is passed andB
is an element of theconvertfrom
argument, thenB.A()
will be invoked to perform the type conversion.Examples:
SE3() SE3(np.identity(4)) SE3([np.identity(4), np.identity(4)]) SE3(SE3()) SE3([SE3(), SE3()]) Twist3(SE3())
- binop(right, op, op2=None, list1=True)
Perform binary operation
- Parameters:
left (BasePoseList subclass) – left operand
right (BasePoseList subclass, scalar or array) – right operand
op (callable) – binary operation
op2 (callable) – binary operation
list1 (bool) – return single array as a list, default True
- Raises:
ValueError – arguments are not compatible
- Returns:
list of values
- Return type:
list
The is a helper method for implementing binary operation with overloaded operators such as
X * Y
whereX
andY
are both subclasses ofBasePoseList
. Each operand has a list of one or more values and this methods computes a list of result values according to:Inputs
Output
len(left)
len(right)
len
operation
1
1
1
ret = op(left, right)
1
M
M
ret[i] = op(left, right[i])
M
1
M
ret[i] = op(left[i], right)
M
M
M
ret[i] = op(left[i], right[i])
The arguments to
op
are the internal numeric values, ie. as returned by the._A
property.The result is always a list, except for the first case above and
list1
isFalse
.If the right operand is not a
BasePoseList
subclass, but is a numeric scalar or array then thenop2
is invokedFor example:
X._binop(Y, lambda x, y: x + y)
Input
Output
len(left)
len
operation
1
1
ret = op2(left, right)
M
M
ret[i] = op2(left[i], right)
There is no check on the shape of
right
if it is an array. The result is always a list, except for the first case above andlist1
isFalse
.
- clear() None -- remove all items from S
- conjugation(A)
Matrix conjugation
- Parameters:
A (ndarray) – matrix to conjugate
- Returns:
conjugated matrix
- Return type:
ndarray
Compute the conjugation \(\mat{X} \mat{A} \mat{X}^{-1}\) where \(\mat{X}\) is the current object.
Example:
>>> from spatialmath import SO2 >>> import numpy as np >>> R = SO2(0.5) >>> A = np.array([[10, 0], [0, 1]]) >>> print(R * A * R.inv()) [[7.9314 3.7866] [3.7866 3.0686]] >>> print(R.conjugation(A)) [[7.9314 3.7866] [3.7866 3.0686]]
- det()
Determinant of rotational component (superclass method)
- Returns:
Determinant of rotational component
- Return type:
float or NumPy array
x.det()
is the determinant of the rotation component of the values ofx
.Example:
>>> x=SE3.Rand() >>> x.det() 1.0000000000000004 >>> x=SE3.Rand(N=2) >>> x.det() [0.9999999999999997, 1.0000000000000002]
- SymPy:
not supported
- eul(unit='rad', flip=False)[source]
SO(3) or SE(3) as Euler angles
- Parameters:
unit (str) – angular units: ‘rad’ [default], or ‘deg’
- Returns:
3-vector of Euler angles
- Return type:
ndarray(3,), ndarray(n,3)
x.eul
is the Euler angle representation of the rotation. Euler angles are a 3-vector \((\phi, \theta, \psi)\) which correspond to consecutive rotations about the Z, Y, Z axes respectively.If
len(x)
is:1, return an ndarray with shape=(3,)
N>1, return ndarray with shape=(3,N)
- eulervec()[source]
SO(3) or SE(3) as Euler vector (exponential coordinates)
- Returns:
\(\theta \hat{\bf v}\)
- Return type:
ndarray(3)
x.eulervec()
is the Euler vector (or exponential coordinates) which is related to angle-axis notation and is the product of the rotation angle and the rotation axis.Example:
>>> from spatialmath import SO3 >>> R = SO3.Rx(0.3) >>> R.eulervec() array([0.3, 0. , 0. ])
Note
If the input is SE(3) the translation component is ignored.
- Seealso:
angvec()
angvec2r()
- extend(iterable)
Extend sequence of values in an instance (BasePoseList superclass method)
- Parameters:
x (instance of same type) – the value to extend
- Raises:
ValueError – incorrect type of appended object
- Return type:
None
Appends the argument’s values to the object’s internal list of values.
Example:
>>> x = X.Alloc(10) >>> len(x) 10 >>> x.append(X.Alloc(5)) # extend the list >>> len(x) 15
where
X
is any of the SMTB classes.
- insert(i, item)
Insert a value to an instance (BasePoseList superclass method)
- Parameters:
i (int) – element to insert value before
item (instance of same type) – the value to insert
- Raises:
ValueError – incorrect type of inserted value
- Return type:
None
Inserts the argument into the object’s internal list of values.
Example:
>>> x = X.Alloc(10) >>> len(x) 10 >>> x.insert(0, X()) # insert at start of list >>> len(x) 11 >>> x.insert(10, X()) # append to the list >>> len(x) 11
where
X
is any of the SMTB classes.Note
If
i
is beyond the end of the list, the item is appended to the list
- interp(end=None, s=None, shortest=True)
Interpolate between poses (superclass method)
- Parameters:
end (same as
self
) – final poses (array_like or int) – interpolation coefficient, range 0 to 1, or number of steps
shortest (bool, default to True) – take the shortest path along the great circle for the rotation
- Returns:
interpolated pose
- Return type:
same as
self
X.interp(Y, s)
interpolates pose between X between when s=0 and Y when s=1.X.interp(Y, N)
interpolates pose between X and Y inN
steps.
Example:
>>> x = SE3(-1, -2, 0) * SE3.Rx(-0.3) >>> y = SE3(1, 2, 0) * SE3.Rx(0.3) >>> x.interp(y, 0) # this is x SE3(array([[ 1. , 0. , 0. , -1. ], [ 0. , 0.9553, 0.2955, -2. ], [ 0. , -0.2955, 0.9553, 0. ], [ 0. , 0. , 0. , 1. ]])) >>> x.interp(y, 1) # this is y SE3(array([[ 1. , 0. , 0. , 1. ], [ 0. , 0.9553, -0.2955, 2. ], [ 0. , 0.2955, 0.9553, 0. ], [ 0. , 0. , 0. , 1. ]])) >>> x.interp(y, 0.5) # this is in between SE3(array([[1., 0., 0., 0.], [0., 1., 0., 0.], [0., 0., 1., 0.], [0., 0., 0., 1.]])) >>> z = x.interp(y, 11) # in 11 steps >>> len(z) 11 >>> z[0] # this is x SE3(array([[ 1. , 0. , 0. , -1. ], [ 0. , 0.9553, 0.2955, -2. ], [ 0. , -0.2955, 0.9553, 0. ], [ 0. , 0. , 0. , 1. ]])) >>> z[5] # this is in between SE3(array([[1., 0., 0., 0.], [0., 1., 0., 0.], [0., 0., 1., 0.], [0., 0., 0., 1.]]))
Note
For SO3 and SE3 rotation is interpolated using quaternion spherical linear interpolation (slerp).
Values of
s
outside the range [0,1] are silently clipped
- Seealso:
- SymPy:
not supported
- interp1(s=None)
Interpolate pose (superclass method)
- Parameters:
end (same as
self
) – final poses (array_like) – interpolation coefficient, range 0 to 1
- Returns:
interpolated pose
- Return type:
X.interp(s)
interpolates pose between identity when s=0, and X when s=1.len(X)
len(s)
len(result)
Result
1
1
1
Y = interp(X, s)
M
1
M
Y[i] = interp(X[i], s)
1
M
M
Y[i] = interp(X, s[i])
Example:
>>> x = SE3.Rx(0.3) >>> print(x.interp(0)) SE3(array([[1., 0., 0., 0.], [0., 1., 0., 0.], [0., 0., 1., 0.], [0., 0., 0., 1.]])) >>> print(x.interp(1)) SE3(array([[ 1. , 0. , 0. , 0. ], [ 0. , 0.95533649, -0.29552021, 0. ], [ 0. , 0.29552021, 0.95533649, 0. ], [ 0. , 0. , 0. , 1. ]])) >>> y = x.interp(x, np.linspace(0, 1, 10)) >>> len(y) 10 >>> y[5] SE3(array([[ 1. , 0. , 0. , 0. ], [ 0. , 0.98614323, -0.16589613, 0. ], [ 0. , 0.16589613, 0.98614323, 0. ], [ 0. , 0. , 0. , 1. ]]))
Notes:
For SO3 and SE3 rotation is interpolated using quaternion spherical linear interpolation (slerp).
- Seealso:
interp()
,trinterp()
,qslerp()
,trinterp2()
- SymPy:
not supported
- inv()[source]
Inverse of SO(3)
- Returns:
inverse
- Return type:
SO2 instance
Efficiently compute the inverse of each of the SO(3) values taking into account the matrix structure. For an SO(3) matrix the inverse is the transpose.
- ishom()
Test if object belongs to SE(3) group (superclass method)
- Returns:
True
if object is instance of SE3- Return type:
bool
For compatibility with Spatial Math Toolbox for MATLAB. In Python use
isinstance(x, SE3)
.Example:
>>> x = SO3() >>> x.isrot() False >>> x = SE3() >>> x.isrot() True
- ishom2()
Test if object belongs to SE(2) group (superclass method)
- Returns:
True
if object is instance of SE2- Return type:
bool
For compatibility with Spatial Math Toolbox for MATLAB. In Python use
isinstance(x, SE2)
.Example:
>>> x = SO2() >>> x.isrot() False >>> x = SE2() >>> x.isrot() True
- isrot()
Test if object belongs to SO(3) group (superclass method)
- Returns:
True
if object is instance of SO3- Return type:
bool
For compatibility with Spatial Math Toolbox for MATLAB. In Python use
isinstance(x, SO3)
.Example:
>>> x = SO3() >>> x.isrot() True >>> x = SE3() >>> x.isrot() False
- isrot2()
Test if object belongs to SO(2) group (superclass method)
- Returns:
True
if object is instance of SO2- Return type:
bool
For compatibility with Spatial Math Toolbox for MATLAB. In Python use
isinstance(x, SO2)
.Example:
>>> x = SO2() >>> x.isrot() True >>> x = SE2() >>> x.isrot() False
- static isvalid(x, check=True)[source]
Test if matrix is valid SO(3)
- Parameters:
x (numpy.ndarray) – matrix to test
- Returns:
True
if the matrix is a valid element of SO(3), ie. it is a 3x3 orthonormal matrix with determinant of +1.- Return type:
bool
- Seealso:
isrot()
- log(twist=False)
Logarithm of pose (superclass method)
- Returns:
logarithm
- Return type:
ndarray
- Raises:
ValueError
An efficient closed-form solution of the matrix logarithm.
Input
Output
Pose
Shape
Structure
SO2
(2,2)
skew-symmetric SE2 (3,3) augmented skew-symmetric
SO3
(3,3)
skew-symmetric SE3 (4,4) augmented skew-symmetric
Example:
>>> x = SE3.Rx(0.3) >>> y = x.log() >>> y array([[ 0. , -0. , 0. , 0. ], [ 0. , 0. , -0.3, 0. ], [-0. , 0.3, 0. , 0. ], [ 0. , 0. , 0. , 0. ]])
- Seealso:
- SymPy:
not supported
- mean(tol=20)[source]
Mean of a set of rotations
- Parameters:
tol (float, optional) – iteration tolerance in units of eps, defaults to 20
- Returns:
the mean rotation
- Return type:
SO3
instance.
Computes the Karcher mean of the set of rotations within the SO(3) instance.
- References:
**Hartley, Trumpf** - “Rotation Averaging” - IJCV 2011, Algorithm 1, page 15.
- norm()
Normalize pose (superclass method)
X.norm()
is an equivalent pose object but the rotational matrix part of all values has been adjusted to ensure it is a proper orthogonal matrix rotation.
Example:
>>> x = SE3() >>> y = x.norm() >>> y SE3(array([[1., 0., 0., 0.], [0., 1., 0., 0.], [0., 0., 1., 0.], [0., 0., 0., 1.]]))
Notes:
Only the direction of A vector (the z-axis) is unchanged.
Used to prevent finite word length arithmetic causing transforms to become ‘unnormalized’.
- plot(*args, **kwargs)
Plot pose object as a coordinate frame (superclass method)
- Parameters:
**kwargs – plotting options
- Return type:
None
X.plot()
displays the poseX
as a coordinate frame in either 2D or 3D. There are many options, see the links below.
Example:
>>> X = SE3.Rx(0.3) >>> X.plot(frame='A', color='green')
(
Source code
,png
,hires.png
,pdf
)
- pop(i=-1)
Pop value from an instance (BasePoseList superclass method)
- Parameters:
i (int) – item in the list to pop, default is last
- Returns:
the popped value
- Return type:
instance of same type
- Raises:
IndexError – if there are no values to pop
Removes a value from the value list and returns it. The original instance is modified.
Example:
>>> x = X.Alloc(10) >>> len(x) 10 >>> y = x.pop() # pop the last value x[9] >>> len(x) 9 >>> y = x.pop(0) # pop the first value x[0] >>> len(x) 8
where
X
is any of the SMTB classes.
- print(label=None, file=None)
Print pose as a matrix (superclass method)
- Parameters:
label (str, optional) – label to print before the matrix, defaults to None
file (file object, optional) – file to write to, defaults to None
- Return type:
None
Print the pose as a matrix, with an optional line beforehand. By default the matrix is printed to stdout.
Example:
>>> from spatialmath import SE3 >>> SE3().print() 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 >>> SE3().print("pose is:") pose is: 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1
- Seealso:
- printline(*args, **kwargs)
Print pose in compact single line format (superclass method)
- Parameters:
arg (str) – value for orient option, optional
label (str) – text label to put at start of line
fmt (str) – conversion format for each number as used by
format()
label – text label to put at start of line
orient (str) – 3-angle convention to use, optional,
SO3
andSE3
onlyunit (str) – angular units: ‘rad’ [default], or ‘deg’
file (file object) – file to write formatted string to. [default, stdout]
- Return type:
None
Print pose in a compact single line format. If
X
has multiple values, print one per line.Orientation can be displayed in various formats:
orient
description
'rpy/zyx'
roll-pitch-yaw angles in ZYX axis order [default]
'rpy/yxz'
roll-pitch-yaw angles in YXZ axis order
'rpy/zyx'
roll-pitch-yaw angles in ZYX axis order
'eul'
Euler angles in ZYZ axis order
'angvec'
angle and axis
Example:
>>> from spatialmath import SE2, SE3 >>> x = SE3.Rx(0.3) >>> x.printline() t = 0, 0, 0; rpy/zyx = 17.2°, 0°, 0° >>> x = SE3.Rx([0.2, 0.3]) >>> x.printline() t = 0, 0, 0; rpy/zyx = 11.5°, 0°, 0° t = 0, 0, 0; rpy/zyx = 17.2°, 0°, 0° >>> x.printline('angvec') t = 0, 0, 0; angvec = (11.5° | 1, 0, 0) t = 0, 0, 0; angvec = (17.2° | 1, 0, 0) >>> x.printline(orient='angvec', fmt="{:.6f}") t = 0.000000, 0.000000, 0.000000; angvec = (11.459156° | 1.000000, 0.000000, 0.000000) t = 0.000000, 0.000000, 0.000000; angvec = (17.188734° | 1.000000, 0.000000, 0.000000) >>> x = SE2(1, 2, 0.3) >>> x.printline() t = 1, 2; 17.2°
Note
Default formatting is for compact display of data
For tabular data set
fmt
to a fixed width format such asfmt='{:.3g}'
- Seealso:
strline()
trprint()
,trprint2()
- prod(norm=False, check=True)
Product of elements (superclass method)
- Parameters:
norm (bool, optional) – normalize the product, defaults to False
check – check that computed matrix is valid member of group, default True
- Bool check:
bool, optional
- Returns:
Product of elements
- Return type:
pose instance
x.prod()
is the product of the values held byx
, ie. \(\prod_i^N T_i\).>>> from spatialmath import SE3 >>> x = SE3.Rx([0, 0.1, 0.2, 0.3]) >>> x.prod() SE3(array([[ 1. , 0. , 0. , 0. ], [ 0. , 0.8253, -0.5646, 0. ], [ 0. , 0.5646, 0.8253, 0. ], [ 0. , 0. , 0. , 1. ]]))
Note
When compounding many transformations the product may become denormalized resulting in a result that is not a proper member of the group. You can either disable membership checking by
check=False
which is risky, or normalize the result bynorm=True
.
- reverse()
S.reverse() – reverse IN PLACE
- rpy(unit='rad', order='zyx')[source]
SO(3) or SE(3) as roll-pitch-yaw angles
- Parameters:
order (str) – angle sequence order, default to ‘zyx’
unit (str) – angular units: ‘rad’ [default], or ‘deg’
- Returns:
3-vector of roll-pitch-yaw angles
- Return type:
ndarray(3,), ndarray(n,3)
x.rpy
is the roll-pitch-yaw angle representation of the rotation. The angles are a 3-vector \((r, p, y)\) which correspond to successive rotations about the axes specified byorder
:'zyx'
[default], rotate by yaw about the z-axis, then by pitch about the new y-axis, then by roll about the new x-axis. Convention for a mobile robot with x-axis forward and y-axis sideways.'xyz'
, rotate by yaw about the x-axis, then by pitch about the new y-axis, then by roll about the new z-axis. Convention for a robot gripper with z-axis forward and y-axis between the gripper fingers.'yxz'
, rotate by yaw about the y-axis, then by pitch about the new x-axis, then by roll about the new z-axis. Convention for a camera with z-axis parallel to the optic axis and x-axis parallel to the pixel rows.
If len(x) is:
1, return an ndarray with shape=(3,)
N>1, return ndarray with shape=(3,N)
- simplify()
Symbolically simplify matrix values (superclass method)
- Returns:
pose with symbolic elements
- Return type:
pose instance
Apply symbolic simplification to every element of every value in the pose instance.
Example:
>>> a = SE3.Rx(sympy.symbols('theta')) >>> b = a * a >>> b SE3(array([[1, 0, 0, 0.0], [0, -sin(theta)**2 + cos(theta)**2, -2*sin(theta)*cos(theta), 0], [0, 2*sin(theta)*cos(theta), -sin(theta)**2 + cos(theta)**2, 0], [0.0, 0, 0, 1.0]], dtype=object) >>> b.simplify() SE3(array([[1, 0, 0, 0], [0, cos(2*theta), -sin(2*theta), 0], [0, sin(2*theta), cos(2*theta), 0], [0, 0, 0, 1.00000000000000]], dtype=object))
- SymPy:
supported
- stack()
Convert to 3-dimensional matrix
- Returns:
3-dimensional NumPy array
- Return type:
ndarray(n,n,m)
Converts the value to a 3-dimensional NumPy array where the values are stacked along the third axis. The first two dimensions are given by
self.shape
.
- strline(*args, **kwargs)
Convert pose to compact single line string (superclass method)
- Parameters:
label (str) – text label to put at start of line
fmt (str) – conversion format for each number as used by
format()
label – text label to put at start of line
orient (str) – 3-angle convention to use, optional,
SO3
andSE3
onlyunit (str) – angular units: ‘rad’ [default], or ‘deg’
- Returns:
pose in string format
- Return type:
str
Convert pose in a compact single line format. If
X
has multiple values, the string has one pose per line.Orientation can be displayed in various formats:
orient
description
'rpy/zyx'
roll-pitch-yaw angles in ZYX axis order [default]
'rpy/yxz'
roll-pitch-yaw angles in YXZ axis order
'rpy/zyx'
roll-pitch-yaw angles in ZYX axis order
'eul'
Euler angles in ZYZ axis order
'angvec'
angle and axis
Example:
>>> from spatialmath import SE2, SE3 >>> x = SE3.Rx(0.3) >>> x.strline() 't = 0, 0, 0; rpy/zyx = 17.2°, 0°, 0°' >>> x = SE3.Rx([0.2, 0.3]) >>> x.strline() 't = 0, 0, 0; rpy/zyx = 11.5°, 0°, 0°t = 0, 0, 0; rpy/zyx = 17.2°, 0°, 0°' >>> x.strline('angvec') 't = 0, 0, 0; angvec = (11.5° | 1, 0, 0)t = 0, 0, 0; angvec = (17.2° | 1, 0, 0)' >>> x.strline(orient='angvec', fmt="{:.6f}") 't = 0.000000, 0.000000, 0.000000; angvec = (11.459156° | 1.000000, 0.000000, 0.000000)t = 0.000000, 0.000000, 0.000000; angvec = (17.188734° | 1.000000, 0.000000, 0.000000)' >>> x = SE2(1, 2, 0.3) >>> x.strline() 't = 1, 2; 17.2°'
Note
Default formatting is for compact display of data
For tabular data set
fmt
to a fixed width format such asfmt='{:.3g}'
- Seealso:
printline()
trprint()
,trprint2()
- unop(op, matrix=False)
Perform unary operation
- Parameters:
self (BasePoseList subclass) – operand
op (callable) – unnary operation
matrix (bool) – return array instead of list, default False
- Returns:
operation results
- Return type:
list or NumPy array
The is a helper method for implementing unary operations where the operand has multiple value. This method computes the value of the operation for all input values and returns the result as either a list or as a matrix which vertically stacks the results.
Input
Output
len(self)
len
operation
1
1
ret = op(self)
M
M
ret[i] = op(self[i])
M
M
ret[i,;] = op(self[i])
The result is:
a list of values if
matrix==False
, ora 2D NumPy stack of values if
matrix==True
, it is assumed that the value is a 1D array.
- property A: List[ndarray[Any, dtype[ScalarType]]] | ndarray[Any, dtype[ScalarType]]
Array value of an instance (BasePoseList superclass method)
- Returns:
NumPy array value of this instance
- Return type:
ndarray
X.A
is a NumPy array that represents the value of this instance, and has a shape given byX.shape
.
Note
This assumes that
len(X)
== 1, ie. it is a single-valued instance.
- property N: int
Dimension of the object’s group (superclass property)
- Returns:
dimension
- Return type:
int
Dimension of the group is 2 for
SO2
orSE2
, and 3 forSO3
orSE3
. This corresponds to the dimension of the space, 2D or 3D, to which these rotations or rigid-body motions apply.Example:
>>> SE3().N 3 >>> SE2().N 2
- property R: SO3Array
SO(3) or SE(3) as rotation matrix
- Returns:
rotational component
- Return type:
ndarray(3,3)
x.R
is the rotation matrix component ofx
as an array with shape (3,3). Iflen(x) > 1
, return an array with shape=(N,3,3).Warning
The i’th rotation matrix is
x[i,:,:]
or simplyx[i]
. This is different to the MATLAB version where the i’th rotation matrix isx(:,:,i)
.Example:
>>> from spatialmath import SO3 >>> x = SO3.Rx(0.3) >>> x.R array([[ 1. , 0. , 0. ], [ 0. , 0.9553, -0.2955], [ 0. , 0.2955, 0.9553]])
- SymPy:
supported
- property a: ndarray[Any, dtype[floating]]
Approach vector of SO(3) or SE(3)
- Returns:
approach vector
- Return type:
ndarray(3)
This is the third column of the rotation submatrix, sometimes called the approach vector. It is parallel to the z-axis of the frame defined by this pose.
- property about: str
Succinct summary of object type and length (superclass property)
- Returns:
succinct summary
- Return type:
str
Displays the type and the number of elements in compact form, for example:
>>> x = SE3([SE3() for i in range(20)]) >>> len(x) 20 >>> print(x.about) SE3[20]
- property isSE: bool
Test if object belongs to SE(n) group (superclass property)
- property isSO: bool
Test if object belongs to SO(n) group (superclass property)
- property n: ndarray[Any, dtype[floating]]
Normal vector of SO(3) or SE(3)
- Returns:
normal vector
- Return type:
ndarray(3)
This is the first column of the rotation submatrix, sometimes called the normal vector. It is parallel to the x-axis of the frame defined by this pose.
- property o: ndarray[Any, dtype[floating]]
Orientation vector of SO(3) or SE(3)
- Returns:
orientation vector
- Return type:
ndarray(3)
This is the second column of the rotation submatrix, sometimes called the orientation vector. It is parallel to the y-axis of the frame defined by this pose.
- property shape: Tuple[int, int]
Shape of the object’s interal matrix representation
- Returns:
(3,3)
- Return type:
tuple
Each value within the
SO3
instance is a NumPy array of this shape.