`scipy.spatial.transform._rigid_transform:RigidTransform.identity`

source: /scipy/spatial/transform/_rigid_transform.py:904

Signature

staticmethoddef identity(num: int | None = None, *, shape: int | tuple[int, ...] | None = None) → RigidTransform

Summary

Initialize an identity transform.

Extended Summary

Composition with the identity transform has no effect, and applying the identity transform to a vector has no effect.

Parameters

num : int, optional: Number of identity transforms to generate. If None (default), then a single transform is generated.
shape : int or tuple of ints, optional: Shape of the identity transforms. If specified, num must be None.

Returns

transform : `RigidTransform` instance: The identity transform.

Examples

from scipy.spatial.transform import RigidTransform as Tf
from scipy.spatial.transform import Rotation as R
import numpy as np

✓

Creating a single identity transform:

tf = Tf.identity()
tf.as_matrix()
tf.single

✓

True

The identity transform can be applied to a vector without effect:

tf.apply([1, 2, 3])

✓

array([1., 2., 3.])

The identity transform when composed with another transform has no effect:

rng = np.random.default_rng(123)
t = rng.random(3)
r = R.random(rng=rng)
tf = Tf.from_components(t, r)
np.allclose((Tf.identity() * tf).as_matrix(),
            tf.as_matrix(), atol=1e-12)

✓

True

Multiple identity transforms can be generated at once:

tf = Tf.identity(2)

✓

tf.as_matrix()

✗

array([[[1., 0., 0., 0.],
        [0., 1., 0., 0.],
        [0., 0., 1., 0.],
        [0., 0., 0., 1.]],

       [[1., 0., 0., 0.],
        [0., 1., 0., 0.],
        [0., 0., 1., 0.],
        [0., 0., 0., 1.]]])

tf.single
len(tf)

✓

Aliases

scipy.spatial.transform.RigidTransform.identity