Add tuto for custom transforms and custom datapoints in gallery example (#7795)

Co-authored-by: Philip Meier <github.pmeier@posteo.de>

docs/source/conf.py

@@ -320,7 +320,7 @@ def inject_weight_metadata(app, what, name, obj, options, lines):
       used within the autoclass directive.
     """
 
-    if obj.__name__.endswith(("_Weights", "_QuantizedWeights")):
+    if getattr(obj, ".__name__", "").endswith(("_Weights", "_QuantizedWeights")):
 
         if len(obj) == 0:
             lines[:] = ["There are no available pre-trained weights."]

docs/source/datapoints.rst

@@ -17,3 +17,4 @@ see e.g. :ref:`sphx_glr_auto_examples_plot_transforms_v2_e2e.py`.
     BoundingBoxFormat
     BoundingBoxes
     Mask
+    Datapoint

docs/source/transforms.rst

@@ -375,3 +375,14 @@ you can use a functional transform to build transform classes with custom behavi
     to_pil_image
     to_tensor
     vflip
+
+Developer tools
+---------------
+
+.. currentmodule:: torchvision.transforms.v2.functional
+
+.. autosummary::
+    :toctree: generated/
+    :template: function.rst
+
+    register_kernel

gallery/plot_custom_datapoints.py

+"""
+=====================================
+How to write your own Datapoint class
+=====================================
+
+This guide is intended for downstream library maintainers. We explain how to
+write your own datapoint class, and how to make it compatible with the built-in
+Torchvision v2 transforms. Before continuing, make sure you have read
+:ref:`sphx_glr_auto_examples_plot_datapoints.py`.
+"""
+
+# %%
+import torch
+import torchvision
+
+# We are using BETA APIs, so we deactivate the associated warning, thereby acknowledging that
+# some APIs may slightly change in the future
+torchvision.disable_beta_transforms_warning()
+
+from torchvision import datapoints
+from torchvision.transforms import v2
+
+# %%
+# We will create a very simple class that just inherits from the base
+# :class:`~torchvision.datapoints.Datapoint` class. It will be enough to cover
+# what you need to know to implement your more elaborate uses-cases. If you need
+# to create a class that carries meta-data, take a look at how the
+# :class:`~torchvision.datapoints.BoundingBoxes` class is `implemented
+# <https://github.com/pytorch/vision/blob/main/torchvision/datapoints/_bounding_box.py>`_.
+
+
+class MyDatapoint(datapoints.Datapoint):
+    pass
+
+
+my_dp = MyDatapoint([1, 2, 3])
+my_dp
+
+# %%
+# Now that we have defined our custom Datapoint class, we want it to be
+# compatible with the built-in torchvision transforms, and the functional API.
+# For that, we need to implement a kernel which performs the core of the
+# transformation, and then "hook" it to the functional that we want to support
+# via :func:`~torchvision.transforms.v2.functional.register_kernel`.
+#
+# We illustrate this process below: we create a kernel for the "horizontal flip"
+# operation of our MyDatapoint class, and register it to the functional API.
+
+from torchvision.transforms.v2 import functional as F
+
+
+@F.register_kernel(dispatcher="hflip", datapoint_cls=MyDatapoint)
+def hflip_my_datapoint(my_dp, *args, **kwargs):
+    print("Flipping!")
+    out = my_dp.flip(-1)
+    return MyDatapoint.wrap_like(my_dp, out)
+
+
+# %%
+# To understand why ``wrap_like`` is used, see
+# :ref:`datapoint_unwrapping_behaviour`. Ignore the ``*args, **kwargs`` for now,
+# we will explain it below in :ref:`param_forwarding`.
+#
+# .. note::
+#
+#     In our call to ``register_kernel`` above we used a string
+#     ``dispatcher="hflip"`` to refer to the functional we want to hook into. We
+#     could also have used the  functional *itself*, i.e.
+#     ``@register_kernel(dispatcher=F.hflip, ...)``.
+#
+#     The functionals that you can be hooked into are the ones in
+#     ``torchvision.transforms.v2.functional`` and they are documented in
+#     :ref:`functional_transforms`.
+#
+# Now that we have registered our kernel, we can call the functional API on a
+# ``MyDatapoint`` instance:
+
+my_dp = MyDatapoint(torch.rand(3, 256, 256))
+_ = F.hflip(my_dp)
+
+# %%
+# And we can also use the
+# :class:`~torchvision.transforms.v2.RandomHorizontalFlip` transform, since it relies on :func:`~torchvision.transforms.v2.functional.hflip` internally:
+t = v2.RandomHorizontalFlip(p=1)
+_ = t(my_dp)
+
+# %%
+# .. note::
+#
+#     We cannot register a kernel for a transform class, we can only register a
+#     kernel for a **functional**. The reason we can't register a transform
+#     class is because one transform may internally rely on more than one
+#     functional, so in general we can't register a single kernel for a given
+#     class.
+#
+# .. _param_forwarding:
+#
+# Parameter forwarding, and ensuring future compatibility of your kernels
+# -----------------------------------------------------------------------
+#
+# The functional API that you're hooking into is public and therefore
+# **backward** compatible: we guarantee that the parameters of these functionals
+# won't be removed or renamed without a proper deprecation cycle. However, we
+# don't guarantee **forward** compatibility, and we may add new parameters in
+# the future.
+#
+# Imagine that in a future version, Torchvision adds a new ``inplace`` parameter
+# to its :func:`~torchvision.transforms.v2.functional.hflip` functional. If you
+# already defined and registered your own kernel as
+
+def hflip_my_datapoint(my_dp):  # noqa
+    print("Flipping!")
+    out = my_dp.flip(-1)
+    return MyDatapoint.wrap_like(my_dp, out)
+
+
+# %%
+# then calling ``F.hflip(my_dp)`` will **fail**, because ``hflip`` will try to
+# pass the new ``inplace`` parameter to your kernel, but your kernel doesn't
+# accept it.
+#
+# For this reason, we recommend to always define your kernels with
+# ``*args, **kwargs`` in their signature, as done above. This way, your kernel
+# will be able to accept any new parameter that we may add in the future.
+# (Technically, adding `**kwargs` only should be enough).

gallery/plot_custom_transforms.py

+"""
+===================================
+How to write your own v2 transforms
+===================================
+
+This guide explains how to write transforms that are compatible with the
+torchvision transforms V2 API.
+"""
+
+# %%
+import torch
+import torchvision
+
+# We are using BETA APIs, so we deactivate the associated warning, thereby acknowledging that
+# some APIs may slightly change in the future
+torchvision.disable_beta_transforms_warning()
+
+from torchvision import datapoints
+from torchvision.transforms import v2
+
+
+# %%
+# Just create a ``nn.Module`` and override the ``forward`` method
+# ===============================================================
+#
+# In most cases, this is all you're going to need, as long as you already know
+# the structure of the input that your transform will expect. For example if
+# you're just doing image classification, your transform will typically accept a
+# single image as input, or a ``(img, label)`` input. So you can just hard-code
+# your ``forward`` method to accept just that, e.g.
+#
+# .. code:: python
+#
+#     class MyCustomTransform(torch.nn.Module):
+#         def forward(self, img, label):
+#             # Do some transformations
+#             return new_img, new_label
+#
+# .. note::
+#
+#     This means that if you have a custom transform that is already compatible
+#     with the V1 transforms (those in ``torchvision.transforms``), it will
+#     still work with the V2 transforms without any change!
+#
+# We will illustrate this more completely below with a typical detection case,
+# where our samples are just images, bounding boxes and labels:
+
+class MyCustomTransform(torch.nn.Module):
+    def forward(self, img, bboxes, label):  # we assume inputs are always structured like this
+        print(
+            f"I'm transforming an image of shape {img.shape} "
+            f"with bboxes = {bboxes}\n{label = }"
+        )
+        # Do some transformations. Here, we're just passing though the input
+        return img, bboxes, label
+
+
+transforms = v2.Compose([
+    MyCustomTransform(),
+    v2.RandomResizedCrop((224, 224), antialias=True),
+    v2.RandomHorizontalFlip(p=1),
+    v2.Normalize(mean=[0, 0, 0], std=[1, 1, 1])
+])
+
+H, W = 256, 256
+img = torch.rand(3, H, W)
+bboxes = datapoints.BoundingBoxes(
+    torch.tensor([[0, 10, 10, 20], [50, 50, 70, 70]]),
+    format="XYXY",
+    canvas_size=(H, W)
+)
+label = 3
+
+out_img, out_bboxes, out_label = transforms(img, bboxes, label)
+# %%
+print(f"Output image shape: {out_img.shape}\nout_bboxes = {out_bboxes}\n{out_label = }")
+# %%
+# .. note::
+#     While working with datapoint classes in your code, make sure to
+#     familiarize yourself with this section:
+#     :ref:`datapoint_unwrapping_behaviour`
+#
+# Supporting arbitrary input structures
+# =====================================
+#
+# In the section above, we have assumed that you already know the structure of
+# your inputs and that you're OK with hard-coding this expected structure in
+# your code. If you want your custom transforms to be as flexible as possible,
+# this can be a bit limitting.
+#
+# A key feature of the builtin Torchvision V2 transforms is that they can accept
+# arbitrary input structure and return the same structure as output (with
+# transformed entries). For example, transforms can accept a single image, or a
+# tuple of ``(img, label)``, or an arbitrary nested dictionary as input:
+
+structured_input = {
+    "img": img,
+    "annotations": (bboxes, label),
+    "something_that_will_be_ignored": (1, "hello")
+}
+structured_output = v2.RandomHorizontalFlip(p=1)(structured_input)
+
+assert isinstance(structured_output, dict)
+assert structured_output["something_that_will_be_ignored"] == (1, "hello")
+print(f"The transformed bboxes are:\n{structured_output['annotations'][0]}")
+
+# %%
+# If you want to reproduce this behavior in your own transform, we invite you to
+# look at our `code
+# <https://github.com/pytorch/vision/blob/main/torchvision/transforms/v2/_transform.py>`_
+# and adapt it to your needs.
+#
+# In brief, the core logic is to unpack the input into a flat list using `pytree
+# <https://github.com/pytorch/pytorch/blob/main/torch/utils/_pytree.py>`_, and
+# then transform only the entries that can be transformed (the decision is made
+# based on the **class** of the entries, as all datapoints are
+# tensor-subclasses) plus some custom logic that is out of score here - check the
+# code for details. The (potentially transformed) entries are then repacked and
+# returned, in the same structure as the input.
+#
+# We do not provide public dev-facing tools to achieve that at this time, but if
+# this is something that would be valuable to you, please let us know by opening
+# an issue on our `GitHub repo <https://github.com/pytorch/vision/issues>`_.

gallery/plot_datapoints.py

@@ -3,13 +3,22 @@
 Datapoints FAQ
 ==============
 
-The :mod:`torchvision.datapoints` namespace was introduced together with ``torchvision.transforms.v2``. This example
-showcases what these datapoints are and how they behave. This is a fairly low-level topic that most users will not need
-to worry about: you do not need to understand the internals of datapoints to efficiently rely on
-``torchvision.transforms.v2``. It may however be useful for advanced users trying to implement their own datasets,
-transforms, or work directly with the datapoints.
+Datapoints are Tensor subclasses introduced together with
+``torchvision.transforms.v2``. This example showcases what these datapoints are
+and how they behave.
+
+.. warning::
+
+    **Intended Audience** Unless you're writing your own transforms or your own datapoints, you
+    probably do not need to read this guide. This is a fairly low-level topic
+    that most users will not need to worry about: you do not need to understand
+    the internals of datapoints to efficiently rely on
+    ``torchvision.transforms.v2``. It may however be useful for advanced users
+    trying to implement their own datasets, transforms, or work directly with
+    the datapoints.
 """
 
+# %%
 import PIL.Image
 
 import torch
@@ -35,11 +44,20 @@ image = datapoints.Image(tensor)
 assert isinstance(image, torch.Tensor)
 assert image.data_ptr() == tensor.data_ptr()
 
-
 # %%
 # Under the hood, they are needed in :mod:`torchvision.transforms.v2` to correctly dispatch to the appropriate function
 # for the input data.
 #
+# What can I do with a datapoint?
+# -------------------------------
+#
+# Datapoints look and feel just like regular tensors - they **are** tensors.
+# Everything that is supported on a plain :class:`torch.Tensor` like ``.sum()`` or
+# any ``torch.*`` operator will also works on datapoints. See
+# :ref:`datapoint_unwrapping_behaviour` for a few gotchas.
+
+# %%
+#
 # What datapoints are supported?
 # ------------------------------
 #
@@ -50,9 +68,14 @@ assert image.data_ptr() == tensor.data_ptr()
 # * :class:`~torchvision.datapoints.BoundingBoxes`
 # * :class:`~torchvision.datapoints.Mask`
 #
+# .. _datapoint_creation:
+#
 # How do I construct a datapoint?
 # -------------------------------
 #
+# Using the constructor
+# ^^^^^^^^^^^^^^^^^^^^^
+#
 # Each datapoint class takes any tensor-like data that can be turned into a :class:`~torch.Tensor`
 
 image = datapoints.Image([[[[0, 1], [1, 0]]]])
@@ -68,27 +91,52 @@ print(float_image)
 
 
 # %%
-# In addition, :class:`~torchvision.datapoints.Image` and :class:`~torchvision.datapoints.Mask` also take a
+# In addition, :class:`~torchvision.datapoints.Image` and :class:`~torchvision.datapoints.Mask` can also take a
 # :class:`PIL.Image.Image` directly:
 
 image = datapoints.Image(PIL.Image.open("assets/astronaut.jpg"))
 print(image.shape, image.dtype)
 
 # %%
-# In general, the datapoints can also store additional metadata that complements the underlying tensor. For example,
-# :class:`~torchvision.datapoints.BoundingBoxes` stores the coordinate format as well as the spatial size of the
-# corresponding image alongside the actual values:
+# Some datapoints require additional metadata to be passed in ordered to be constructed. For example,
+# :class:`~torchvision.datapoints.BoundingBoxes` requires the coordinate format as well as the size of the
+# corresponding image (``canvas_size``) alongside the actual values. These
+# metadata are required to properly transform the bounding boxes.
 
-bounding_box = datapoints.BoundingBoxes(
-    [17, 16, 344, 495], format=datapoints.BoundingBoxFormat.XYXY, canvas_size=image.shape[-2:]
+bboxes = datapoints.BoundingBoxes(
+    [[17, 16, 344, 495], [0, 10, 0, 10]],
+    format=datapoints.BoundingBoxFormat.XYXY,
+    canvas_size=image.shape[-2:]
 )
-print(bounding_box)
+print(bboxes)
+
+# %%
+# Using the ``wrap_like()`` class method
+# ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+#
+# You can also use the ``wrap_like()`` class method to wrap a tensor object
+# into a datapoint. This is useful when you already have an object of the
+# desired type, which typically happens when writing transforms: you just want
+# to wrap the output like the input. This API is inspired by utils like
+# :func:`torch.zeros_like`:
+
+new_bboxes = torch.tensor([0, 20, 30, 40])
+new_bboxes = datapoints.BoundingBoxes.wrap_like(bboxes, new_bboxes)
+assert isinstance(new_bboxes, datapoints.BoundingBoxes)
+assert new_bboxes.canvas_size == bboxes.canvas_size
 
 
 # %%
+# The metadata of ``new_bboxes`` is the same as ``bboxes``, but you could pass
+# it as a parameter to override it. Check the
+# :meth:`~torchvision.datapoints.BoundingBoxes.wrap_like` documentation for
+# more details.
+#
 # Do I have to wrap the output of the datasets myself?
 # ----------------------------------------------------
 #
+# TODO: Move this in another guide - this is user-facing, not dev-facing.
+#
 # Only if you are using custom datasets. For the built-in ones, you can use
 # :func:`torchvision.datasets.wrap_dataset_for_transforms_v2`. Note that the function also supports subclasses of the
 # built-in datasets. Meaning, if your custom dataset subclasses from a built-in one and the output type is the same, you
@@ -105,8 +153,8 @@ class PennFudanDataset(torch.utils.data.Dataset):
     def __getitem__(self, item):
         ...
 
-        target["boxes"] = datapoints.BoundingBoxes(
-            boxes,
+        target["bboxes"] = datapoints.BoundingBoxes(
+            bboxes,
             format=datapoints.BoundingBoxFormat.XYXY,
             canvas_size=F.get_size(img),
         )
@@ -147,7 +195,7 @@ def get_transform(train):
 # %%
 # .. note::
 #
-#    If both :class:`~torchvision.datapoints.BoundingBoxes`'es and :class:`~torchvision.datapoints.Mask`'s are included in
+#    If both :class:`~torchvision.datapoints.BoundingBoxes` and :class:`~torchvision.datapoints.Mask`'s are included in
 #    the sample, ``torchvision.transforms.v2`` will transform them both. Meaning, if you don't need both, dropping or
 #    at least not wrapping the obsolete parts, can lead to a significant performance boost.
 #
@@ -156,41 +204,66 @@ def get_transform(train):
 #    even better to not load the masks at all, but this is not possible in this example, since the bounding boxes are
 #    generated from the masks.
 #
-# How do the datapoints behave inside a computation?
-# --------------------------------------------------
+# .. _datapoint_unwrapping_behaviour:
 #
-# Datapoints look and feel just like regular tensors. Everything that is supported on a plain :class:`torch.Tensor`
-# also works on datapoints.
-# Since for most operations involving datapoints, it cannot be safely inferred whether the result should retain the
-# datapoint type, we choose to return a plain tensor instead of a datapoint (this might change, see note below):
+# I had a Datapoint but now I have a Tensor. Help!
+# ------------------------------------------------
+#
+# For a lot of operations involving datapoints, we cannot safely infer whether
+# the result should retain the datapoint type, so we choose to return a plain
+# tensor instead of a datapoint (this might change, see note below):
 
 
-assert isinstance(image, datapoints.Image)
+assert isinstance(bboxes, datapoints.BoundingBoxes)
 
-new_image = image + 0
+# Shift bboxes by 3 pixels in both H and W
+new_bboxes = bboxes + 3
 
-assert isinstance(new_image, torch.Tensor) and not isinstance(new_image, datapoints.Image)
+assert isinstance(new_bboxes, torch.Tensor) and not isinstance(new_bboxes, datapoints.BoundingBoxes)
+
+# %%
+# If you're writing your own custom transforms or code involving datapoints, you
+# can re-wrap the output into a datapoint by just calling their constructor, or
+# by using the ``.wrap_like()`` class method:
+
+new_bboxes = bboxes + 3
+new_bboxes = datapoints.BoundingBoxes.wrap_like(bboxes, new_bboxes)
+assert isinstance(new_bboxes, datapoints.BoundingBoxes)
 
 # %%
+# See more details above in :ref:`datapoint_creation`.
+#
+# .. note::
+#
+#    You never need to re-wrap manually if you're using the built-in transforms
+#    or their functional equivalents: this is automatically taken care of for
+#    you.
+#
 # .. note::
 #
 #    This "unwrapping" behaviour is something we're actively seeking feedback on. If you find this surprising or if you
 #    have any suggestions on how to better support your use-cases, please reach out to us via this issue:
 #    https://github.com/pytorch/vision/issues/7319
 #
-# There are two exceptions to this rule:
+# There are a few exceptions to this "unwrapping" rule:
 #
-# 1. The operations :meth:`~torch.Tensor.clone`, :meth:`~torch.Tensor.to`, and :meth:`~torch.Tensor.requires_grad_`
-#    retain the datapoint type.
-# 2. Inplace operations on datapoints cannot change the type of the datapoint they are called on. However, if you use
-#    the flow style, the returned value will be unwrapped:
+# 1. Operations like :meth:`~torch.Tensor.clone`, :meth:`~torch.Tensor.to`,
+#    :meth:`torch.Tensor.detach` and :meth:`~torch.Tensor.requires_grad_` retain
+#    the datapoint type.
+# 2. Inplace operations on datapoints like ``.add_()`` preserve they type. However,
+#    the **returned** value of inplace operations will be unwrapped into a pure
+#    tensor:
 
 image = datapoints.Image([[[0, 1], [1, 0]]])
 
 new_image = image.add_(1).mul_(2)
 
-assert isinstance(image, torch.Tensor)
+# image got transformed in-place and is still an Image datapoint, but new_image
+# is a Tensor. They share the same underlying data and they're equal, just
+# different classes.
+assert isinstance(image, datapoints.Image)
 print(image)
 
 assert isinstance(new_image, torch.Tensor) and not isinstance(new_image, datapoints.Image)
 assert (new_image == image).all()
+assert new_image.data_ptr() == image.data_ptr()

torchvision/datapoints/_bounding_box.py

@@ -42,7 +42,7 @@ class BoundingBoxes(Datapoint):
     canvas_size: Tuple[int, int]
 
     @classmethod
-    def _wrap(cls, tensor: torch.Tensor, *, format: BoundingBoxFormat, canvas_size: Tuple[int, int]) -> BoundingBoxes:
+    def _wrap(cls, tensor: torch.Tensor, *, format: BoundingBoxFormat, canvas_size: Tuple[int, int]) -> BoundingBoxes:  # type: ignore[override]
         bounding_boxes = tensor.as_subclass(cls)
         bounding_boxes.format = format
         bounding_boxes.canvas_size = canvas_size

torchvision/datapoints/_datapoint.py

@@ -14,6 +14,13 @@ _FillTypeJIT = Optional[List[float]]
 
 
 class Datapoint(torch.Tensor):
+    """[Beta] Base class for all datapoints.
+
+    You probably don't want to use this class unless you're defining your own
+    custom Datapoints. See
+    :ref:`sphx_glr_auto_examples_plot_custom_datapoints.py` for details.
+    """
+
     @staticmethod
     def _to_tensor(
         data: Any,
@@ -25,9 +32,13 @@ class Datapoint(torch.Tensor):
             requires_grad = data.requires_grad if isinstance(data, torch.Tensor) else False
         return torch.as_tensor(data, dtype=dtype, device=device).requires_grad_(requires_grad)
 
+    @classmethod
+    def _wrap(cls: Type[D], tensor: torch.Tensor) -> D:
+        return tensor.as_subclass(cls)
+
     @classmethod
     def wrap_like(cls: Type[D], other: D, tensor: torch.Tensor) -> D:
-        raise NotImplementedError
+        return cls._wrap(tensor)
 
     _NO_WRAPPING_EXCEPTIONS = {
         torch.Tensor.clone: lambda cls, input, output: cls.wrap_like(input, output),

torchvision/datapoints/_image.py

@@ -22,11 +22,6 @@ class Image(Datapoint):
             ``data`` is a :class:`torch.Tensor`, the value is taken from it. Otherwise, defaults to ``False``.
     """
 
-    @classmethod
-    def _wrap(cls, tensor: torch.Tensor) -> Image:
-        image = tensor.as_subclass(cls)
-        return image
-
     def __new__(
         cls,
         data: Any,
@@ -48,10 +43,6 @@ class Image(Datapoint):
 
         return cls._wrap(tensor)
 
-    @classmethod
-    def wrap_like(cls, other: Image, tensor: torch.Tensor) -> Image:
-        return cls._wrap(tensor)
-
     def __repr__(self, *, tensor_contents: Any = None) -> str:  # type: ignore[override]
         return self._make_repr()
 

torchvision/datapoints/_mask.py

@@ -22,10 +22,6 @@ class Mask(Datapoint):
             ``data`` is a :class:`torch.Tensor`, the value is taken from it. Otherwise, defaults to ``False``.
     """
 
-    @classmethod
-    def _wrap(cls, tensor: torch.Tensor) -> Mask:
-        return tensor.as_subclass(cls)
-
     def __new__(
         cls,
         data: Any,
@@ -41,11 +37,3 @@ class Mask(Datapoint):
 
         tensor = cls._to_tensor(data, dtype=dtype, device=device, requires_grad=requires_grad)
         return cls._wrap(tensor)
-
-    @classmethod
-    def wrap_like(
-        cls,
-        other: Mask,
-        tensor: torch.Tensor,
-    ) -> Mask:
-        return cls._wrap(tensor)

torchvision/datapoints/_video.py

@@ -20,11 +20,6 @@ class Video(Datapoint):
             ``data`` is a :class:`torch.Tensor`, the value is taken from it. Otherwise, defaults to ``False``.
     """
 
-    @classmethod
-    def _wrap(cls, tensor: torch.Tensor) -> Video:
-        video = tensor.as_subclass(cls)
-        return video
-
     def __new__(
         cls,
         data: Any,
@@ -38,10 +33,6 @@ class Video(Datapoint):
             raise ValueError
         return cls._wrap(tensor)
 
-    @classmethod
-    def wrap_like(cls, other: Video, tensor: torch.Tensor) -> Video:
-        return cls._wrap(tensor)
-
     def __repr__(self, *, tensor_contents: Any = None) -> str:  # type: ignore[override]
         return self._make_repr()
 

torchvision/prototype/datapoints/_label.py

@@ -15,7 +15,7 @@ class _LabelBase(Datapoint):
     categories: Optional[Sequence[str]]
 
     @classmethod
-    def _wrap(cls: Type[L], tensor: torch.Tensor, *, categories: Optional[Sequence[str]]) -> L:
+    def _wrap(cls: Type[L], tensor: torch.Tensor, *, categories: Optional[Sequence[str]]) -> L:  # type: ignore[override]
         label_base = tensor.as_subclass(cls)
         label_base.categories = categories
         return label_base

torchvision/transforms/v2/functional/_utils.py

@@ -47,6 +47,11 @@ def _name_to_dispatcher(name):
 
 
 def register_kernel(dispatcher, datapoint_cls):
+    """Decorate a kernel to register it for a dispatcher and a (custom) datapoint type.
+
+    See :ref:`sphx_glr_auto_examples_plot_custom_datapoints.py` for usage
+    details.
+    """
     if isinstance(dispatcher, str):
         dispatcher = _name_to_dispatcher(name=dispatcher)
     return _register_kernel_internal(dispatcher, datapoint_cls, datapoint_wrapper=False)