Class CastToType

monai/transforms/utility/array.py:337–380

Cast the Numpy data to specified numpy data type, or cast the PyTorch Tensor to specified PyTorch data type. Example: >>> import numpy as np >>> import torch >>> transform = CastToType(dtype=np.float32) >>> # Example with a numpy array >>> img_n

class CastToType(Transform):
    """
    Cast the Numpy data to specified numpy data type, or cast the PyTorch Tensor to
    specified PyTorch data type.

    Example:
        >>> import numpy as np
        >>> import torch
        >>> transform = CastToType(dtype=np.float32)

        >>> # Example with a numpy array
        >>> img_np = np.array([0, 127, 255], dtype=np.uint8)
        >>> img_np_casted = transform(img_np)
        >>> img_np_casted
        array([  0. , 127. , 255. ], dtype=float32)

        >>> # Example with a PyTorch tensor
        >>> img_tensor = torch.tensor([0, 127, 255], dtype=torch.uint8)
        >>> img_tensor_casted = transform(img_tensor)
        >>> img_tensor_casted
        tensor([  0., 127., 255.])  # dtype is float32
    """

    backend = [TransformBackends.TORCH, TransformBackends.NUMPY]

    def __init__(self, dtype=np.float32) -> None:
        """
        Args:
            dtype: convert image to this data type, default is `np.float32`.
        """
        self.dtype = dtype

    def __call__(self, img: NdarrayOrTensor, dtype: DtypeLike | torch.dtype = None) -> NdarrayOrTensor:
        """
        Apply the transform to `img`, assuming `img` is a numpy array or PyTorch Tensor.

        Args:
            dtype: convert image to this data type, default is `self.dtype`.

        Raises:
            TypeError: When ``img`` type is not in ``Union[numpy.ndarray, torch.Tensor]``.

        """
        return convert_data_type(img, output_type=type(img), dtype=dtype or self.dtype)[0]


class ToTensor(Transform):