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Composition API (core.composition)

class BaseCompose (transforms, p, mask_interpolation=None, seed=None, save_applied_params=False) [view source on GitHub]

Base class for composing multiple transforms together.

This class serves as a foundation for creating compositions of transforms in the Albumentations library. It provides basic functionality for managing a sequence of transforms and applying them to data.

Attributes:

Name Type Description
transforms List[TransformType]

A list of transforms to be applied.

p float

Probability of applying the compose. Should be in the range [0, 1].

replay_mode bool

If True, the compose is in replay mode.

_additional_targets Dict[str, str]

Additional targets for transforms.

_available_keys Set[str]

Set of available keys for data.

processors Dict[str, Union[BboxProcessor, KeypointsProcessor]]

Processors for specific data types.

Parameters:

Name Type Description
transforms TransformsSeqType

A sequence of transforms to compose.

p float

Probability of applying the compose.

Exceptions:

Type Description
ValueError

If an invalid additional target is specified.

Note

  • Subclasses should implement the call method to define how the composition is applied to data.
  • The class supports serialization and deserialization of transforms.
  • It provides methods for adding targets, setting deterministic behavior, and checking data validity post-transform.

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Source code in albumentations/core/composition.py
Python
class BaseCompose(Serializable):
    """Base class for composing multiple transforms together.

    This class serves as a foundation for creating compositions of transforms
    in the Albumentations library. It provides basic functionality for
    managing a sequence of transforms and applying them to data.

    Attributes:
        transforms (List[TransformType]): A list of transforms to be applied.
        p (float): Probability of applying the compose. Should be in the range [0, 1].
        replay_mode (bool): If True, the compose is in replay mode.
        _additional_targets (Dict[str, str]): Additional targets for transforms.
        _available_keys (Set[str]): Set of available keys for data.
        processors (Dict[str, Union[BboxProcessor, KeypointsProcessor]]): Processors for specific data types.

    Args:
        transforms (TransformsSeqType): A sequence of transforms to compose.
        p (float): Probability of applying the compose.

    Raises:
        ValueError: If an invalid additional target is specified.

    Note:
        - Subclasses should implement the __call__ method to define how
          the composition is applied to data.
        - The class supports serialization and deserialization of transforms.
        - It provides methods for adding targets, setting deterministic behavior,
          and checking data validity post-transform.
    """

    _transforms_dict: dict[int, BasicTransform] | None = None
    check_each_transform: tuple[DataProcessor, ...] | None = None
    main_compose: bool = True

    def __init__(
        self,
        transforms: TransformsSeqType,
        p: float,
        mask_interpolation: int | None = None,
        seed: int | None = None,
        save_applied_params: bool = False,
    ):
        if isinstance(transforms, (BaseCompose, BasicTransform)):
            warnings.warn(
                "transforms is single transform, but a sequence is expected! Transform will be wrapped into list.",
                stacklevel=2,
            )
            transforms = [transforms]

        self.transforms = transforms
        self.p = p

        self.replay_mode = False
        self._additional_targets: dict[str, str] = {}
        self._available_keys: set[str] = set()
        self.processors: dict[str, BboxProcessor | KeypointsProcessor] = {}
        self._set_keys()
        self.set_mask_interpolation(mask_interpolation)
        self.seed = seed
        self.random_generator = np.random.default_rng(seed)
        self.py_random = random.Random(seed)
        self.set_random_seed(seed)
        self.save_applied_params = save_applied_params

    def _track_transform_params(self, transform: TransformType, data: dict[str, Any]) -> None:
        """Track transform parameters if tracking is enabled."""
        if "applied_transforms" in data and hasattr(transform, "params") and transform.params:
            data["applied_transforms"].append((transform.__class__.__name__, transform.params.copy()))

    def set_random_state(
        self,
        random_generator: np.random.Generator,
        py_random: random.Random,
    ) -> None:
        """Set random state directly from generators.

        Args:
            random_generator: numpy random generator to use
            py_random: python random generator to use
        """
        self.random_generator = random_generator
        self.py_random = py_random

        # Propagate both random states to all transforms
        for transform in self.transforms:
            if isinstance(transform, (BasicTransform, BaseCompose)):
                transform.set_random_state(random_generator, py_random)

    def set_random_seed(self, seed: int | None) -> None:
        """Set random state from seed.

        Args:
            seed: Random seed to use
        """
        self.seed = seed
        self.random_generator = np.random.default_rng(seed)
        self.py_random = random.Random(seed)

        # Propagate seed to all transforms
        for transform in self.transforms:
            if isinstance(transform, (BasicTransform, BaseCompose)):
                transform.set_random_seed(seed)

    def set_mask_interpolation(self, mask_interpolation: int | None) -> None:
        self.mask_interpolation = mask_interpolation
        self._set_mask_interpolation_recursive(self.transforms)

    def _set_mask_interpolation_recursive(self, transforms: TransformsSeqType) -> None:
        for transform in transforms:
            if isinstance(transform, BasicTransform):
                if hasattr(transform, "mask_interpolation") and self.mask_interpolation is not None:
                    transform.mask_interpolation = self.mask_interpolation
            elif isinstance(transform, BaseCompose):
                transform.set_mask_interpolation(self.mask_interpolation)

    def __iter__(self) -> Iterator[TransformType]:
        return iter(self.transforms)

    def __len__(self) -> int:
        return len(self.transforms)

    def __call__(self, *args: Any, **data: Any) -> dict[str, Any]:
        raise NotImplementedError

    def __getitem__(self, item: int) -> TransformType:
        return self.transforms[item]

    def __repr__(self) -> str:
        return self.indented_repr()

    @property
    def additional_targets(self) -> dict[str, str]:
        return self._additional_targets

    @property
    def available_keys(self) -> set[str]:
        return self._available_keys

    def indented_repr(self, indent: int = REPR_INDENT_STEP) -> str:
        args = {k: v for k, v in self.to_dict_private().items() if not (k.startswith("__") or k == "transforms")}
        repr_string = self.__class__.__name__ + "(["
        for t in self.transforms:
            repr_string += "\n"
            t_repr = t.indented_repr(indent + REPR_INDENT_STEP) if hasattr(t, "indented_repr") else repr(t)
            repr_string += " " * indent + t_repr + ","
        repr_string += "\n" + " " * (indent - REPR_INDENT_STEP) + f"], {format_args(args)})"
        return repr_string

    @classmethod
    def get_class_fullname(cls) -> str:
        return get_shortest_class_fullname(cls)

    @classmethod
    def is_serializable(cls) -> bool:
        return True

    def to_dict_private(self) -> dict[str, Any]:
        return {
            "__class_fullname__": self.get_class_fullname(),
            "p": self.p,
            "transforms": [t.to_dict_private() for t in self.transforms],
        }

    def get_dict_with_id(self) -> dict[str, Any]:
        return {
            "__class_fullname__": self.get_class_fullname(),
            "id": id(self),
            "params": None,
            "transforms": [t.get_dict_with_id() for t in self.transforms],
        }

    def add_targets(self, additional_targets: dict[str, str] | None) -> None:
        if additional_targets:
            for k, v in additional_targets.items():
                if k in self._additional_targets and v != self._additional_targets[k]:
                    raise ValueError(
                        f"Trying to overwrite existed additional targets. "
                        f"Key={k} Exists={self._additional_targets[k]} New value: {v}",
                    )
            self._additional_targets.update(additional_targets)
            for t in self.transforms:
                t.add_targets(additional_targets)
            for proc in self.processors.values():
                proc.add_targets(additional_targets)
        self._set_keys()

    def _set_keys(self) -> None:
        """Set _available_keys"""
        self._available_keys.update(self._additional_targets.keys())
        for t in self.transforms:
            self._available_keys.update(t.available_keys)
            if hasattr(t, "targets_as_params"):
                self._available_keys.update(t.targets_as_params)
        if self.processors:
            self._available_keys.update(["labels"])
            for proc in self.processors.values():
                if proc.default_data_name not in self._available_keys:  # if no transform to process this data
                    warnings.warn(
                        f"Got processor for {proc.default_data_name}, but no transform to process it.",
                        stacklevel=2,
                    )
                self._available_keys.update(proc.data_fields)
                if proc.params.label_fields:
                    self._available_keys.update(proc.params.label_fields)

    def set_deterministic(self, flag: bool, save_key: str = "replay") -> None:
        for t in self.transforms:
            t.set_deterministic(flag, save_key)

    def check_data_post_transform(self, data: Any) -> dict[str, Any]:
        if self.check_each_transform:
            image_shape = get_shape(data["image"])

            for proc in self.check_each_transform:
                for data_name in data:
                    if data_name in proc.data_fields or (
                        data_name in self._additional_targets
                        and self._additional_targets[data_name] in proc.data_fields
                    ):
                        data[data_name] = proc.filter(data[data_name], image_shape)
        return data

class Compose (transforms, bbox_params=None, keypoint_params=None, additional_targets=None, p=1.0, is_check_shapes=True, strict=True, mask_interpolation=None, seed=None, save_applied_params=False) [view source on GitHub]

Compose multiple transforms together and apply them sequentially to input data.

This class allows you to chain multiple image augmentation transforms and apply them in a specified order. It also handles bounding box and keypoint transformations if the appropriate parameters are provided.

Parameters:

Name Type Description
transforms List[Union[BasicTransform, BaseCompose]]

A list of transforms to apply.

bbox_params Union[dict, BboxParams, None]

Parameters for bounding box transforms. Can be a dict of params or a BboxParams object. Default is None.

keypoint_params Union[dict, KeypointParams, None]

Parameters for keypoint transforms. Can be a dict of params or a KeypointParams object. Default is None.

additional_targets Dict[str, str]

A dictionary mapping additional target names to their types. For example, {'image2': 'image'}. Default is None.

p float

Probability of applying all transforms. Should be in range [0, 1]. Default is 1.0.

is_check_shapes bool

If True, checks consistency of shapes for image/mask/masks on each call. Disable only if you are sure about your data consistency. Default is True.

strict bool

If True, raises an error on unknown input keys. If False, ignores them. Default is True.

mask_interpolation int

Interpolation method for mask transforms. When defined, it overrides the interpolation method specified in individual transforms. Default is None.

seed int

Random seed. Default is None.

save_applied_params bool

If True, saves the applied parameters of each transform. Default is False.

Examples:

Python
>>> import albumentations as A
>>> transform = A.Compose([
...     A.RandomCrop(width=256, height=256),
...     A.HorizontalFlip(p=0.5),
...     A.RandomBrightnessContrast(p=0.2),
... ])
>>> transformed = transform(image=image)

Note

  • The class checks the validity of input data and shapes if is_check_args and is_check_shapes are True.
  • When bbox_params or keypoint_params are provided, it sets up the corresponding processors.
  • The transform can handle additional targets specified in the additional_targets dictionary.

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Source code in albumentations/core/composition.py
Python
class Compose(BaseCompose, HubMixin):
    """Compose multiple transforms together and apply them sequentially to input data.

    This class allows you to chain multiple image augmentation transforms and apply them
    in a specified order. It also handles bounding box and keypoint transformations if
    the appropriate parameters are provided.

    Args:
        transforms (List[Union[BasicTransform, BaseCompose]]): A list of transforms to apply.
        bbox_params (Union[dict, BboxParams, None]): Parameters for bounding box transforms.
            Can be a dict of params or a BboxParams object. Default is None.
        keypoint_params (Union[dict, KeypointParams, None]): Parameters for keypoint transforms.
            Can be a dict of params or a KeypointParams object. Default is None.
        additional_targets (Dict[str, str], optional): A dictionary mapping additional target names
            to their types. For example, {'image2': 'image'}. Default is None.
        p (float): Probability of applying all transforms. Should be in range [0, 1]. Default is 1.0.
        is_check_shapes (bool): If True, checks consistency of shapes for image/mask/masks on each call.
            Disable only if you are sure about your data consistency. Default is True.
        strict (bool): If True, raises an error on unknown input keys. If False, ignores them. Default is True.
        mask_interpolation (int, optional): Interpolation method for mask transforms. When defined,
            it overrides the interpolation method specified in individual transforms. Default is None.
        seed (int, optional): Random seed. Default is None.
        save_applied_params (bool): If True, saves the applied parameters of each transform. Default is False.

    Example:
        >>> import albumentations as A
        >>> transform = A.Compose([
        ...     A.RandomCrop(width=256, height=256),
        ...     A.HorizontalFlip(p=0.5),
        ...     A.RandomBrightnessContrast(p=0.2),
        ... ])
        >>> transformed = transform(image=image)

    Note:
        - The class checks the validity of input data and shapes if is_check_args and is_check_shapes are True.
        - When bbox_params or keypoint_params are provided, it sets up the corresponding processors.
        - The transform can handle additional targets specified in the additional_targets dictionary.
    """

    def __init__(
        self,
        transforms: TransformsSeqType,
        bbox_params: dict[str, Any] | BboxParams | None = None,
        keypoint_params: dict[str, Any] | KeypointParams | None = None,
        additional_targets: dict[str, str] | None = None,
        p: float = 1.0,
        is_check_shapes: bool = True,
        strict: bool = True,
        mask_interpolation: int | None = None,
        seed: int | None = None,
        save_applied_params: bool = False,
    ):
        super().__init__(
            transforms=transforms,
            p=p,
            mask_interpolation=mask_interpolation,
            seed=seed,
            save_applied_params=save_applied_params,
        )

        if bbox_params:
            if isinstance(bbox_params, dict):
                b_params = BboxParams(**bbox_params)
            elif isinstance(bbox_params, BboxParams):
                b_params = bbox_params
            else:
                msg = "unknown format of bbox_params, please use `dict` or `BboxParams`"
                raise ValueError(msg)
            self.processors["bboxes"] = BboxProcessor(b_params)

        if keypoint_params:
            if isinstance(keypoint_params, dict):
                k_params = KeypointParams(**keypoint_params)
            elif isinstance(keypoint_params, KeypointParams):
                k_params = keypoint_params
            else:
                msg = "unknown format of keypoint_params, please use `dict` or `KeypointParams`"
                raise ValueError(msg)
            self.processors["keypoints"] = KeypointsProcessor(k_params)

        for proc in self.processors.values():
            proc.ensure_transforms_valid(self.transforms)

        self.add_targets(additional_targets)
        if not self.transforms:  # if no transforms -> do nothing, all keys will be available
            self._available_keys.update(AVAILABLE_KEYS)

        self.is_check_args = True
        self.strict = strict

        self.is_check_shapes = is_check_shapes
        self.check_each_transform = tuple(  # processors that checks after each transform
            proc for proc in self.processors.values() if getattr(proc.params, "check_each_transform", False)
        )
        self._set_check_args_for_transforms(self.transforms)

        self._set_processors_for_transforms(self.transforms)

        self.save_applied_params = save_applied_params

    def _set_processors_for_transforms(self, transforms: TransformsSeqType) -> None:
        for transform in transforms:
            if isinstance(transform, BasicTransform):
                if hasattr(transform, "set_processors"):
                    transform.set_processors(self.processors)
            elif isinstance(transform, BaseCompose):
                self._set_processors_for_transforms(transform.transforms)

    def _set_check_args_for_transforms(self, transforms: TransformsSeqType) -> None:
        for transform in transforms:
            if isinstance(transform, BaseCompose):
                self._set_check_args_for_transforms(transform.transforms)
                transform.check_each_transform = self.check_each_transform
                transform.processors = self.processors
            if isinstance(transform, Compose):
                transform.disable_check_args_private()

    def disable_check_args_private(self) -> None:
        self.is_check_args = False
        self.strict = False
        self.main_compose = False

    def __call__(self, *args: Any, force_apply: bool = False, **data: Any) -> dict[str, Any]:
        if args:
            msg = "You have to pass data to augmentations as named arguments, for example: aug(image=image)"
            raise KeyError(msg)

        if not isinstance(force_apply, (bool, int)):
            msg = "force_apply must have bool or int type"
            raise TypeError(msg)

        # Initialize applied_transforms only in top-level Compose if requested
        if self.save_applied_params and self.main_compose:
            data["applied_transforms"] = []

        need_to_run = force_apply or self.py_random.random() < self.p
        if not need_to_run:
            return data

        self.preprocess(data)

        for t in self.transforms:
            data = t(**data)
            self._track_transform_params(t, data)
            data = self.check_data_post_transform(data)

        return self.postprocess(data)

    def preprocess(self, data: Any) -> None:
        if self.strict:
            for data_name in data:
                if (
                    data_name not in self._available_keys
                    and data_name not in MASK_KEYS
                    and data_name not in IMAGE_KEYS
                    and data_name != "applied_transforms"
                ):
                    msg = f"Key {data_name} is not in available keys."
                    raise ValueError(msg)
        if self.is_check_args:
            self._check_args(**data)
        if self.main_compose:
            for p in self.processors.values():
                p.ensure_data_valid(data)
            for p in self.processors.values():
                p.preprocess(data)

    def postprocess(self, data: dict[str, Any]) -> dict[str, Any]:
        if self.main_compose:
            for p in self.processors.values():
                p.postprocess(data)
        return data

    def to_dict_private(self) -> dict[str, Any]:
        dictionary = super().to_dict_private()
        bbox_processor = self.processors.get("bboxes")
        keypoints_processor = self.processors.get("keypoints")
        dictionary.update(
            {
                "bbox_params": bbox_processor.params.to_dict_private() if bbox_processor else None,
                "keypoint_params": (keypoints_processor.params.to_dict_private() if keypoints_processor else None),
                "additional_targets": self.additional_targets,
                "is_check_shapes": self.is_check_shapes,
            },
        )
        return dictionary

    def get_dict_with_id(self) -> dict[str, Any]:
        dictionary = super().get_dict_with_id()
        bbox_processor = self.processors.get("bboxes")
        keypoints_processor = self.processors.get("keypoints")
        dictionary.update(
            {
                "bbox_params": bbox_processor.params.to_dict_private() if bbox_processor else None,
                "keypoint_params": (keypoints_processor.params.to_dict_private() if keypoints_processor else None),
                "additional_targets": self.additional_targets,
                "params": None,
                "is_check_shapes": self.is_check_shapes,
            },
        )
        return dictionary

    @staticmethod
    def _check_single_data(data_name: str, data: Any) -> tuple[int, int]:
        if not isinstance(data, np.ndarray):
            raise TypeError(f"{data_name} must be numpy array type")
        return data.shape[:2]

    @staticmethod
    def _check_masks_data(data_name: str, data: Any) -> tuple[int, int]:
        if isinstance(data, np.ndarray):
            if data.ndim not in [3, 4]:
                raise TypeError(f"{data_name} must be a 3D or 4D numpy array")
            return data.shape[1:3] if data.ndim == NUM_MULTI_CHANNEL_DIMENSIONS else data.shape[:2]
        if isinstance(data, Sequence):
            if not all(isinstance(m, np.ndarray) for m in data):
                raise TypeError(f"All elements in {data_name} must be numpy arrays")
            if any(m.ndim not in [2, 3] for m in data):
                raise TypeError(f"All masks in {data_name} must be 2D or 3D numpy arrays")
            return data[0].shape[:2]

        raise TypeError(f"{data_name} must be either a numpy array or a sequence of numpy arrays")

    @staticmethod
    def _check_multi_data(data_name: str, data: Any) -> tuple[int, int]:
        if not isinstance(data, Sequence) or not isinstance(data[0], np.ndarray):
            raise TypeError(f"{data_name} must be list of numpy arrays")
        return data[0].shape[:2]

    @staticmethod
    def _check_bbox_keypoint_params(internal_data_name: str, processors: dict[str, Any]) -> None:
        if internal_data_name in CHECK_BBOX_PARAM and processors.get("bboxes") is None:
            raise ValueError("bbox_params must be specified for bbox transformations")
        if internal_data_name in CHECK_KEYPOINTS_PARAM and processors.get("keypoints") is None:
            raise ValueError("keypoints_params must be specified for keypoint transformations")

    @staticmethod
    def _check_shapes(shapes: list[tuple[int, int]], is_check_shapes: bool) -> None:
        if is_check_shapes and shapes and shapes.count(shapes[0]) != len(shapes):
            raise ValueError(
                "Height and Width of image, mask or masks should be equal. You can disable shapes check "
                "by setting a parameter is_check_shapes=False of Compose class (do it only if you are sure "
                "about your data consistency).",
            )

    def _check_args(self, **kwargs: Any) -> None:
        shapes = []

        for data_name, data in kwargs.items():
            internal_data_name = self._additional_targets.get(data_name, data_name)

            if internal_data_name in CHECKED_SINGLE:
                shapes.append(self._check_single_data(data_name, data))

            if internal_data_name in CHECKED_MULTI and data is not None and len(data):
                if internal_data_name == "masks":
                    shapes.append(self._check_masks_data(data_name, data))
                else:
                    shapes.append(self._check_multi_data(data_name, data))

            self._check_bbox_keypoint_params(internal_data_name, self.processors)

        self._check_shapes(shapes, self.is_check_shapes)

class OneOf (transforms, p=0.5) [view source on GitHub]

Select one of transforms to apply. Selected transform will be called with force_apply=True. Transforms probabilities will be normalized to one 1, so in this case transforms probabilities works as weights.

Parameters:

Name Type Description
transforms list

list of transformations to compose.

p float

probability of applying selected transform. Default: 0.5.

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Source code in albumentations/core/composition.py
Python
class OneOf(BaseCompose):
    """Select one of transforms to apply. Selected transform will be called with `force_apply=True`.
    Transforms probabilities will be normalized to one 1, so in this case transforms probabilities works as weights.

    Args:
        transforms (list): list of transformations to compose.
        p (float): probability of applying selected transform. Default: 0.5.

    """

    def __init__(self, transforms: TransformsSeqType, p: float = 0.5):
        super().__init__(transforms=transforms, p=p)
        transforms_ps = [t.p for t in self.transforms]
        s = sum(transforms_ps)
        self.transforms_ps = [t / s for t in transforms_ps]

    def __call__(self, *args: Any, force_apply: bool = False, **data: Any) -> dict[str, Any]:
        if self.replay_mode:
            for t in self.transforms:
                data = t(**data)
            return data

        if self.transforms_ps and (force_apply or self.py_random.random() < self.p):
            idx: int = self.random_generator.choice(len(self.transforms), p=self.transforms_ps)
            t = self.transforms[idx]
            data = t(force_apply=True, **data)
            self._track_transform_params(t, data)
        return data

class OneOrOther (first=None, second=None, transforms=None, p=0.5) [view source on GitHub]

Select one or another transform to apply. Selected transform will be called with force_apply=True.

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Source code in albumentations/core/composition.py
Python
class OneOrOther(BaseCompose):
    """Select one or another transform to apply. Selected transform will be called with `force_apply=True`."""

    def __init__(
        self,
        first: TransformType | None = None,
        second: TransformType | None = None,
        transforms: TransformsSeqType | None = None,
        p: float = 0.5,
    ):
        if transforms is None:
            if first is None or second is None:
                msg = "You must set both first and second or set transforms argument."
                raise ValueError(msg)
            transforms = [first, second]
        super().__init__(transforms, p)
        if len(self.transforms) != NUM_ONEOF_TRANSFORMS:
            warnings.warn("Length of transforms is not equal to 2.", stacklevel=2)

    def __call__(self, *args: Any, force_apply: bool = False, **data: Any) -> dict[str, Any]:
        if self.replay_mode:
            for t in self.transforms:
                data = t(**data)
                self._track_transform_params(t, data)
            return data

        if self.py_random.random() < self.p:
            return self.transforms[0](force_apply=True, **data)

        return self.transforms[-1](force_apply=True, **data)

class RandomOrder (transforms, n=1, replace=False, p=1) [view source on GitHub]

Apply a random subset of transforms from the given list in a random order.

The RandomOrder class allows you to select a specified number of transforms from a list and apply them to the input data in a random order. This is useful for creating more diverse augmentation pipelines where the order of transformations can vary, potentially leading to different results.

Attributes:

Name Type Description
transforms TransformsSeqType

A list of transformations to choose from.

n int

The number of transforms to apply. If n is greater than the number of available transforms and replace is False, n will be set to the number of available transforms.

replace bool

Whether to sample transforms with replacement. If True, the same transform can be selected multiple times. Default is False.

p float

Probability of applying the selected transforms. Should be in the range [0, 1]. Default is 1.0.

Examples:

Python
>>> import albumentations as A
>>> transform = A.RandomOrder([
...     A.HorizontalFlip(p=1),
...     A.VerticalFlip(p=1),
...     A.RandomBrightnessContrast(p=1),
... ], n=2, replace=False, p=0.5)
>>> # This will apply 2 out of the 3 transforms in a random order with 50% probability

Note

  • The probabilities of individual transforms are used as weights for sampling.
  • When replace is True, the same transform can be selected multiple times.
  • The random order of transforms will not be replayed in ReplayCompose.

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Source code in albumentations/core/composition.py
Python
class RandomOrder(SomeOf):
    """Apply a random subset of transforms from the given list in a random order.

    The `RandomOrder` class allows you to select a specified number of transforms from a list and apply them
    to the input data in a random order. This is useful for creating more diverse augmentation pipelines
    where the order of transformations can vary, potentially leading to different results.

    Attributes:
        transforms (TransformsSeqType): A list of transformations to choose from.
        n (int): The number of transforms to apply. If `n` is greater than the number of available transforms
                 and `replace` is False, `n` will be set to the number of available transforms.
        replace (bool): Whether to sample transforms with replacement. If True, the same transform can be
                        selected multiple times. Default is False.
        p (float): Probability of applying the selected transforms. Should be in the range [0, 1]. Default is 1.0.

    Example:
        >>> import albumentations as A
        >>> transform = A.RandomOrder([
        ...     A.HorizontalFlip(p=1),
        ...     A.VerticalFlip(p=1),
        ...     A.RandomBrightnessContrast(p=1),
        ... ], n=2, replace=False, p=0.5)
        >>> # This will apply 2 out of the 3 transforms in a random order with 50% probability

    Note:
        - The probabilities of individual transforms are used as weights for sampling.
        - When `replace` is True, the same transform can be selected multiple times.
        - The random order of transforms will not be replayed in `ReplayCompose`.
    """

    def __init__(self, transforms: TransformsSeqType, n: int = 1, replace: bool = False, p: float = 1):
        super().__init__(transforms=transforms, n=n, replace=replace, p=p)

    def _get_idx(self) -> np.ndarray[np.int_]:
        return self.random_generator.choice(
            len(self.transforms),
            size=self.n,
            replace=self.replace,
            p=self.transforms_ps,
        )

class SelectiveChannelTransform (transforms, channels=(0, 1, 2), p=1.0) [view source on GitHub]

A transformation class to apply specified transforms to selected channels of an image.

This class extends BaseCompose to allow selective application of transformations to specified image channels. It extracts the selected channels, applies the transformations, and then reinserts the transformed channels back into their original positions in the image.

Parameters:

Name Type Description
transforms TransformsSeqType

A sequence of transformations (from Albumentations) to be applied to the specified channels.

channels Sequence[int]

A sequence of integers specifying the indices of the channels to which the transforms should be applied.

p float

Probability that the transform will be applied; the default is 1.0 (always apply).

Methods

call(args, *kwargs): Applies the transforms to the image according to the specified channels. The input data should include 'image' key with the image array.

Returns:

Type Description
dict[str, Any]

The transformed data dictionary, which includes the transformed 'image' key.

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Source code in albumentations/core/composition.py
Python
class SelectiveChannelTransform(BaseCompose):
    """A transformation class to apply specified transforms to selected channels of an image.

    This class extends BaseCompose to allow selective application of transformations to
    specified image channels. It extracts the selected channels, applies the transformations,
    and then reinserts the transformed channels back into their original positions in the image.

    Parameters:
        transforms (TransformsSeqType):
            A sequence of transformations (from Albumentations) to be applied to the specified channels.
        channels (Sequence[int]):
            A sequence of integers specifying the indices of the channels to which the transforms should be applied.
        p (float):
            Probability that the transform will be applied; the default is 1.0 (always apply).

    Methods:
        __call__(*args, **kwargs):
            Applies the transforms to the image according to the specified channels.
            The input data should include 'image' key with the image array.

    Returns:
        dict[str, Any]: The transformed data dictionary, which includes the transformed 'image' key.
    """

    def __init__(
        self,
        transforms: TransformsSeqType,
        channels: Sequence[int] = (0, 1, 2),
        p: float = 1.0,
    ) -> None:
        super().__init__(transforms, p)
        self.channels = channels

    def __call__(self, *args: Any, force_apply: bool = False, **data: Any) -> dict[str, Any]:
        if force_apply or self.py_random.random() < self.p:
            image = data["image"]

            selected_channels = image[:, :, self.channels]
            sub_image = np.ascontiguousarray(selected_channels)

            for t in self.transforms:
                sub_image = t(image=sub_image)["image"]
                self._track_transform_params(t, sub_image)

            transformed_channels = cv2.split(sub_image)
            output_img = image.copy()

            for idx, channel in zip(self.channels, transformed_channels):
                output_img[:, :, idx] = channel

            data["image"] = np.ascontiguousarray(output_img)

        return data

class Sequential (transforms, p=0.5) [view source on GitHub]

Sequentially applies all transforms to targets.

Note

This transform is not intended to be a replacement for Compose. Instead, it should be used inside Compose the same way OneOf or OneOrOther are used. For instance, you can combine OneOf with Sequential to create an augmentation pipeline that contains multiple sequences of augmentations and applies one randomly chose sequence to input data (see the Example section for an example definition of such pipeline).

Examples:

Python
>>> import albumentations as A
>>> transform = A.Compose([
>>>    A.OneOf([
>>>        A.Sequential([
>>>            A.HorizontalFlip(p=0.5),
>>>            A.ShiftScaleRotate(p=0.5),
>>>        ]),
>>>        A.Sequential([
>>>            A.VerticalFlip(p=0.5),
>>>            A.RandomBrightnessContrast(p=0.5),
>>>        ]),
>>>    ], p=1)
>>> ])

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Source code in albumentations/core/composition.py
Python
class Sequential(BaseCompose):
    """Sequentially applies all transforms to targets.

    Note:
        This transform is not intended to be a replacement for `Compose`. Instead, it should be used inside `Compose`
        the same way `OneOf` or `OneOrOther` are used. For instance, you can combine `OneOf` with `Sequential` to
        create an augmentation pipeline that contains multiple sequences of augmentations and applies one randomly
        chose sequence to input data (see the `Example` section for an example definition of such pipeline).

    Example:
        >>> import albumentations as A
        >>> transform = A.Compose([
        >>>    A.OneOf([
        >>>        A.Sequential([
        >>>            A.HorizontalFlip(p=0.5),
        >>>            A.ShiftScaleRotate(p=0.5),
        >>>        ]),
        >>>        A.Sequential([
        >>>            A.VerticalFlip(p=0.5),
        >>>            A.RandomBrightnessContrast(p=0.5),
        >>>        ]),
        >>>    ], p=1)
        >>> ])

    """

    def __init__(self, transforms: TransformsSeqType, p: float = 0.5):
        super().__init__(transforms, p)

    def __call__(self, *args: Any, force_apply: bool = False, **data: Any) -> dict[str, Any]:
        if self.replay_mode or force_apply or self.py_random.random() < self.p:
            for t in self.transforms:
                data = t(**data)
                self._track_transform_params(t, data)
                data = self.check_data_post_transform(data)
        return data

class SomeOf (transforms, n=1, replace=False, p=1) [view source on GitHub]

Apply a random subset of transforms from the given list.

This class selects a specified number of transforms from the provided list and applies them to the input data. The selection can be done with or without replacement, allowing for the same transform to be potentially applied multiple times.

Parameters:

Name Type Description
transforms List[Union[BasicTransform, BaseCompose]]

A list of transforms to choose from.

n int

The number of transforms to apply. If greater than the number of transforms and replace=False, it will be set to the number of transforms.

replace bool

Whether to sample transforms with replacement. Default is True.

p float

Probability of applying the selected transforms. Should be in the range [0, 1]. Default is 1.0.

mask_interpolation int

Interpolation method for mask transforms. When defined, it overrides the interpolation method specified in individual transforms. Default is None.

Note

  • If n is greater than the number of transforms and replace is False, n will be set to the number of transforms with a warning.
  • The probabilities of individual transforms are used as weights for sampling.
  • When replace is True, the same transform can be selected multiple times.

Examples:

Python
>>> import albumentations as A
>>> transform = A.SomeOf([
...     A.HorizontalFlip(p=1),
...     A.VerticalFlip(p=1),
...     A.RandomBrightnessContrast(p=1),
... ], n=2, replace=False, p=0.5)
>>> # This will apply 2 out of the 3 transforms with 50% probability

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Source code in albumentations/core/composition.py
Python
class SomeOf(BaseCompose):
    """Apply a random subset of transforms from the given list.

    This class selects a specified number of transforms from the provided list
    and applies them to the input data. The selection can be done with or without
    replacement, allowing for the same transform to be potentially applied multiple times.

    Args:
        transforms (List[Union[BasicTransform, BaseCompose]]): A list of transforms to choose from.
        n (int): The number of transforms to apply. If greater than the number of
                 transforms and replace=False, it will be set to the number of transforms.
        replace (bool): Whether to sample transforms with replacement. Default is True.
        p (float): Probability of applying the selected transforms. Should be in the range [0, 1].
                   Default is 1.0.
        mask_interpolation (int, optional): Interpolation method for mask transforms.
                                            When defined, it overrides the interpolation method
                                            specified in individual transforms. Default is None.

    Note:
        - If `n` is greater than the number of transforms and `replace` is False,
          `n` will be set to the number of transforms with a warning.
        - The probabilities of individual transforms are used as weights for sampling.
        - When `replace` is True, the same transform can be selected multiple times.

    Example:
        >>> import albumentations as A
        >>> transform = A.SomeOf([
        ...     A.HorizontalFlip(p=1),
        ...     A.VerticalFlip(p=1),
        ...     A.RandomBrightnessContrast(p=1),
        ... ], n=2, replace=False, p=0.5)
        >>> # This will apply 2 out of the 3 transforms with 50% probability
    """

    def __init__(self, transforms: TransformsSeqType, n: int = 1, replace: bool = False, p: float = 1):
        super().__init__(transforms, p)
        self.n = n
        if not replace and n > len(self.transforms):
            self.n = len(self.transforms)
            warnings.warn(
                f"`n` is greater than number of transforms. `n` will be set to {self.n}.",
                UserWarning,
                stacklevel=2,
            )
        self.replace = replace
        transforms_ps = [t.p for t in self.transforms]
        s = sum(transforms_ps)
        self.transforms_ps = [t / s for t in transforms_ps]

    def __call__(self, *arg: Any, force_apply: bool = False, **data: Any) -> dict[str, Any]:
        if self.replay_mode:
            for t in self.transforms:
                data = t(**data)
                data = self.check_data_post_transform(data)
            return data

        if self.transforms_ps and (force_apply or self.py_random.random() < self.p):
            for i in self._get_idx():
                t = self.transforms[i]
                data = t(force_apply=True, **data)
                self._track_transform_params(t, data)
                data = self.check_data_post_transform(data)
        return data

    def _get_idx(self) -> np.ndarray[np.int_]:
        idx = self.random_generator.choice(
            len(self.transforms),
            size=self.n,
            replace=self.replace,
            p=self.transforms_ps,
        )
        idx.sort()
        return idx

    def to_dict_private(self) -> dict[str, Any]:
        dictionary = super().to_dict_private()
        dictionary.update({"n": self.n, "replace": self.replace})
        return dictionary