Source code for monai.transforms.inverse_batch_transform

# Copyright 2020 - 2021 MONAI Consortium
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#     http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
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import warnings
from typing import Any, Callable, Dict, Optional, Sequence

from torch.utils.data import Dataset
from torch.utils.data.dataloader import DataLoader as TorchDataLoader

from monai.data.dataloader import DataLoader
from monai.data.utils import decollate_batch, no_collation, pad_list_data_collate
from monai.transforms.croppad.batch import PadListDataCollate
from monai.transforms.inverse import InvertibleTransform
from monai.transforms.transform import Transform
from monai.utils import first

__all__ = ["BatchInverseTransform"]


class _BatchInverseDataset(Dataset):
    def __init__(
        self,
        data: Sequence[Any],
        transform: InvertibleTransform,
        pad_collation_used: bool,
    ) -> None:
        self.data = data
        self.invertible_transform = transform
        self.pad_collation_used = pad_collation_used

    def __getitem__(self, index: int):
        data = dict(self.data[index])
        # If pad collation was used, then we need to undo this first
        if self.pad_collation_used:
            data = PadListDataCollate.inverse(data)

        if not isinstance(self.invertible_transform, InvertibleTransform):
            warnings.warn("transform is not invertible, can't invert transform for the input data.")
            return data
        return self.invertible_transform.inverse(data)

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


[docs]class BatchInverseTransform(Transform): """ Perform inverse on a batch of data. This is useful if you have inferred a batch of images and want to invert them all. """ def __init__( self, transform: InvertibleTransform, loader: TorchDataLoader, collate_fn: Optional[Callable] = no_collation, num_workers: Optional[int] = 0, detach: bool = True, ) -> None: """ Args: transform: a callable data transform on input data. loader: data loader used to run `transforms` and generate the batch of data. collate_fn: how to collate data after inverse transformations. default won't do any collation, so the output will be a list of size batch size. num_workers: number of workers when run data loader for inverse transforms, default to 0 as only run 1 iteration and multi-processing may be even slower. if the transforms are really slow, set num_workers for multi-processing. if set to `None`, use the `num_workers` of the transform data loader. detach: whether to detach the tensors. Scalars tensors will be detached into number types instead of torch tensors. """ self.transform = transform self.batch_size = loader.batch_size self.num_workers = loader.num_workers if num_workers is None else num_workers self.collate_fn = collate_fn self.detach = detach self.pad_collation_used = loader.collate_fn.__doc__ == pad_list_data_collate.__doc__ def __call__(self, data: Dict[str, Any]) -> Any: decollated_data = decollate_batch(data, detach=self.detach) inv_ds = _BatchInverseDataset(decollated_data, self.transform, self.pad_collation_used) inv_loader = DataLoader( inv_ds, batch_size=self.batch_size, num_workers=self.num_workers, collate_fn=self.collate_fn ) try: return first(inv_loader) except RuntimeError as re: re_str = str(re) if "equal size" in re_str: re_str += "\nMONAI hint: try creating `BatchInverseTransform` with `collate_fn=lambda x: x`." raise RuntimeError(re_str)