__getitem__ for Transform3D

Summary: Implements the `__getitem__` method for `Transform3D`

Reviewed By: nikhilaravi

Differential Revision: D23813975

fbshipit-source-id: 5da752ed8ea029ad0af58bb7a7856f0995519b7a

pytorch3d/transforms/transform3d.py

@@ -2,7 +2,7 @@
 
 import math
 import warnings
-from typing import Optional
+from typing import List, Optional, Union
 
 import torch
 
@@ -172,6 +172,22 @@ class Transform3d:
     def __len__(self):
         return self.get_matrix().shape[0]
 
+    def __getitem__(
+        self, index: Union[int, List[int], slice, torch.Tensor]
+    ) -> "Transform3d":
+        """
+        Args:
+            index: Specifying the index of the transform to retrieve.
+                Can be an int, slice, list of ints, boolean, long tensor.
+                Supports negative indices.
+
+        Returns:
+            Transform3d object with selected transforms. The tensors are not cloned.
+        """
+        if isinstance(index, int):
+            index = [index]
+        return self.__class__(matrix=self.get_matrix()[index])
+
     def compose(self, *others):
         """
         Return a new Transform3d with the tranforms to compose stored as
@@ -361,6 +377,9 @@ class Transform3d:
     def scale(self, *args, **kwargs):
         return self.compose(Scale(device=self.device, *args, **kwargs))
 
+    def rotate(self, *args, **kwargs):
+        return self.compose(Rotate(device=self.device, *args, **kwargs))
+
     def rotate_axis_angle(self, *args, **kwargs):
         return self.compose(RotateAxisAngle(device=self.device, *args, **kwargs))
 

tests/test_transforms.py

@@ -5,6 +5,7 @@ import math
 import unittest
 
 import torch
+from common_testing import TestCaseMixin
 from pytorch3d.transforms.so3 import so3_exponential_map
 from pytorch3d.transforms.transform3d import (
     Rotate,
@@ -15,7 +16,7 @@ from pytorch3d.transforms.transform3d import (
 )
 
 
-class TestTransform(unittest.TestCase):
+class TestTransform(TestCaseMixin, unittest.TestCase):
     def test_to(self):
         tr = Translate(torch.FloatTensor([[1.0, 2.0, 3.0]]))
         R = torch.FloatTensor([[0.0, 1.0, 0.0], [0.0, 0.0, 1.0], [1.0, 0.0, 0.0]])
@@ -89,6 +90,22 @@ class TestTransform(unittest.TestCase):
         self.assertTrue(torch.allclose(points_out, points_out_expected))
         self.assertTrue(torch.allclose(normals_out, normals_out_expected))
 
+    def test_rotate(self):
+        R = so3_exponential_map(torch.randn((1, 3)))
+        t = Transform3d().rotate(R)
+        points = torch.tensor([[1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.5, 0.5, 0.0]]).view(
+            1, 3, 3
+        )
+        normals = torch.tensor(
+            [[1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [1.0, 1.0, 0.0]]
+        ).view(1, 3, 3)
+        points_out = t.transform_points(points)
+        normals_out = t.transform_normals(normals)
+        points_out_expected = torch.bmm(points, R)
+        normals_out_expected = torch.bmm(normals, R)
+        self.assertTrue(torch.allclose(points_out, points_out_expected))
+        self.assertTrue(torch.allclose(normals_out, normals_out_expected))
+
     def test_scale(self):
         t = Transform3d().scale(2.0).scale(0.5, 0.25, 1.0)
         points = torch.tensor([[1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.5, 0.5, 0.0]]).view(
@@ -237,6 +254,103 @@ class TestTransform(unittest.TestCase):
             for m in (m1, m2, m3, m4):
                 self.assertTrue(torch.allclose(m, m5, atol=1e-3))
 
+    def _check_indexed_transforms(self, t3d, t3d_selected, indices):
+        t3d_matrix = t3d.get_matrix()
+        t3d_selected_matrix = t3d_selected.get_matrix()
+        for order_index, selected_index in indices:
+            self.assertClose(
+                t3d_matrix[selected_index], t3d_selected_matrix[order_index]
+            )
+
+    def test_get_item(self, batch_size=5):
+        device = torch.device("cuda:0")
+
+        matrices = torch.randn(
+            size=[batch_size, 4, 4], device=device, dtype=torch.float32
+        )
+
+        # init the Transforms3D class
+        t3d = Transform3d(matrix=matrices)
+
+        # int index
+        index = 1
+        t3d_selected = t3d[index]
+        self.assertEqual(len(t3d_selected), 1)
+        self._check_indexed_transforms(t3d, t3d_selected, [(0, 1)])
+
+        # negative int index
+        index = -1
+        t3d_selected = t3d[index]
+        self.assertEqual(len(t3d_selected), 1)
+        self._check_indexed_transforms(t3d, t3d_selected, [(0, -1)])
+
+        # list index
+        index = [1, 2]
+        t3d_selected = t3d[index]
+        self.assertEqual(len(t3d_selected), len(index))
+        self._check_indexed_transforms(t3d, t3d_selected, enumerate(index))
+
+        # empty list index
+        index = []
+        t3d_selected = t3d[index]
+        self.assertEqual(len(t3d_selected), 0)
+        self.assertEqual(t3d_selected.get_matrix().nelement(), 0)
+
+        # slice index
+        index = slice(0, 2, 1)
+        t3d_selected = t3d[index]
+        self.assertEqual(len(t3d_selected), 2)
+        self._check_indexed_transforms(t3d, t3d_selected, [(0, 0), (1, 1)])
+
+        # empty slice index
+        index = slice(0, 0, 1)
+        t3d_selected = t3d[index]
+        self.assertEqual(len(t3d_selected), 0)
+        self.assertEqual(t3d_selected.get_matrix().nelement(), 0)
+
+        # bool tensor
+        index = (torch.rand(batch_size) > 0.5).to(device)
+        index[:2] = True  # make sure smth is selected
+        t3d_selected = t3d[index]
+        self.assertEqual(len(t3d_selected), index.sum())
+        self._check_indexed_transforms(
+            t3d,
+            t3d_selected,
+            zip(
+                torch.arange(index.sum()),
+                torch.nonzero(index, as_tuple=False).squeeze(),
+            ),
+        )
+
+        # all false bool tensor
+        index = torch.zeros(batch_size).bool()
+        t3d_selected = t3d[index]
+        self.assertEqual(len(t3d_selected), 0)
+        self.assertEqual(t3d_selected.get_matrix().nelement(), 0)
+
+        # int tensor
+        index = torch.tensor([1, 2], dtype=torch.int64, device=device)
+        t3d_selected = t3d[index]
+        self.assertEqual(len(t3d_selected), index.numel())
+        self._check_indexed_transforms(t3d, t3d_selected, enumerate(index.tolist()))
+
+        # negative int tensor
+        index = -(torch.tensor([1, 2], dtype=torch.int64, device=device))
+        t3d_selected = t3d[index]
+        self.assertEqual(len(t3d_selected), index.numel())
+        self._check_indexed_transforms(t3d, t3d_selected, enumerate(index.tolist()))
+
+        # invalid index
+        for invalid_index in (
+            torch.tensor([1, 0, 1], dtype=torch.float32, device=device),  # float tensor
+            1.2,  # float index
+            torch.tensor(
+                [[1, 0, 1], [1, 0, 1]], dtype=torch.int32, device=device
+            ),  # multidimensional tensor
+        ):
+            with self.assertRaises(IndexError):
+                t3d_selected = t3d[invalid_index]
+
 
 class TestTranslate(unittest.TestCase):
     def test_python_scalar(self):