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Pull Request — master (#258)
by Fernando
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torchio.data.image.Image.__init__()   C

Complexity

Conditions 10

Size

Total Lines 48
Code Lines 37

Duplication

Lines 0
Ratio 0 %

Importance

Changes 0
Metric Value
cc 10
eloc 37
nop 9
dl 0
loc 48
rs 5.9999
c 0
b 0
f 0

How to fix   Complexity    Many Parameters   

Complexity

Complex classes like torchio.data.image.Image.__init__() often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes.

Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.

Many Parameters

Methods with many parameters are not only hard to understand, but their parameters also often become inconsistent when you need more, or different data.

There are several approaches to avoid long parameter lists:

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import warnings
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from pathlib import Path
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from typing import Any, Dict, Tuple, Optional
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import torch
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import humanize
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import numpy as np
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import nibabel as nib
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import SimpleITK as sitk
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from ..utils import (
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    nib_to_sitk,
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    get_rotation_and_spacing_from_affine,
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    get_stem,
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    ensure_4d,
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)
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from ..torchio import (
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    TypeData,
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    TypePath,
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    TypeTripletInt,
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    TypeTripletFloat,
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    DATA,
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    TYPE,
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    AFFINE,
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    PATH,
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    STEM,
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    INTENSITY,
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    LABEL,
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)
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from .io import read_image, write_image
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PROTECTED_KEYS = DATA, AFFINE, TYPE, PATH, STEM
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class Image(dict):
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    r"""TorchIO image.
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    For information about medical image orientation, check out `NiBabel docs`_,
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    the `3D Slicer wiki`_, `Graham Wideman's website`_, `FSL docs`_ or
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    `SimpleITK docs`_.
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    Args:
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        path: Path to a file that can be read by
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            :mod:`SimpleITK` or :mod:`nibabel`, or to a directory containing
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            DICOM files. If :py:attr:`tensor` is given, the data in
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            :py:attr:`path` will not be read. The data is expected to be 2D or
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            3D, and may have multiple channels (see :attr:`num_spatial_dims` and
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            :attr:`channels_last`).
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        type: Type of image, such as :attr:`torchio.INTENSITY` or
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            :attr:`torchio.LABEL`. This will be used by the transforms to
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            decide whether to apply an operation, or which interpolation to use
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            when resampling. For example, `preprocessing`_ and `augmentation`_
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            intensity transforms will only be applied to images with type
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            :attr:`torchio.INTENSITY`. Spatial transforms will be applied to
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            all types, and nearest neighbor interpolation is always used to
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            resample images with type :attr:`torchio.LABEL`.
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            The type :attr:`torchio.SAMPLING_MAP` may be used with instances of
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            :py:class:`~torchio.data.sampler.weighted.WeightedSampler`.
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        tensor: If :py:attr:`path` is not given, :attr:`tensor` must be a 4D
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            :py:class:`torch.Tensor` or NumPy array with dimensions
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            :math:`(C, D, H, W)`. If it is not 4D, TorchIO will try to guess
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            the dimensions meanings. If 2D, the shape will be interpreted as
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            :math:`(H, W)`. If 3D, the number of spatial dimensions should be
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            determined in :attr:`num_spatial_dims`. If :attr:`num_spatial_dims`
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            is not given and the shape is 3 along the first or last dimensions,
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            it will be interpreted as a multichannel 2D image. Otherwise, it
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            be interpreted as a 3D image with a single channel.
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        affine: If :attr:`path` is not given, :attr:`affine` must be a
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            :math:`4 \times 4` NumPy array. If ``None``, :attr:`affine` is an
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            identity matrix.
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        check_nans: If ``True``, issues a warning if NaNs are found
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            in the image. If ``False``, images will not be checked for the
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            presence of NaNs.
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        num_spatial_dims: If ``2`` and the input tensor has 3 dimensions, it
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            will be interpreted as a multichannel 2D image. If ``3`` and the
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            input has 3 dimensions, it will be interpreted as a
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            single-channel 3D volume.
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        channels_last: If ``True``, the last dimension of the input will be
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            interpreted as the channels. Defaults to ``True`` if :attr:`path` is
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            given and ``False`` otherwise.
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        **kwargs: Items that will be added to the image dictionary, e.g.
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            acquisition parameters.
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    Example:
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        >>> import torch
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        >>> import torchio
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        >>> # Loading from a file
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        >>> t1_image = torchio.Image('t1.nii.gz', type=torchio.INTENSITY)
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        >>> label_image = torchio.Image('t1_seg.nii.gz', type=torchio.LABEL)
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        >>> image = torchio.Image(tensor=torch.rand(3, 4, 5))
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        >>> image = torchio.Image('safe_image.nrrd', check_nans=False)
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        >>> data, affine = image.data, image.affine
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        >>> affine.shape
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        (4, 4)
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        >>> image.data is image[torchio.DATA]
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        True
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        >>> image.data is image.tensor
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        True
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        >>> type(image.data)
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        torch.Tensor
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    TorchIO images are `lazy loaders`_, i.e. the data is only loaded from disk
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    when needed.
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    Example:
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        >>> import torchio
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        >>> image = torchio.Image('t1.nii.gz')
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        >>> image  # not loaded yet
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        Image(path: t1.nii.gz; type: intensity)
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        >>> times_two = 2 * image.data  # data is loaded and cached here
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        >>> image
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        Image(shape: (1, 256, 256, 176); spacing: (1.00, 1.00, 1.00); orientation: PIR+; memory: 44.0 MiB; type: intensity)
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        >>> image.save('doubled_image.nii.gz')
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    .. _lazy loaders: https://en.wikipedia.org/wiki/Lazy_loading
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    .. _preprocessing: https://torchio.readthedocs.io/transforms/preprocessing.html#intensity
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    .. _augmentation: https://torchio.readthedocs.io/transforms/augmentation.html#intensity
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    .. _NiBabel docs: https://nipy.org/nibabel/image_orientation.html
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    .. _3D Slicer wiki: https://www.slicer.org/wiki/Coordinate_systems
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    .. _FSL docs: https://fsl.fmrib.ox.ac.uk/fsl/fslwiki/Orientation%20Explained
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    .. _SimpleITK docs: https://simpleitk.readthedocs.io/en/master/fundamentalConcepts.html
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    .. _Graham Wideman's website: http://www.grahamwideman.com/gw/brain/orientation/orientterms.htm
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    """
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    def __init__(
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            self,
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            path: Optional[TypePath] = None,
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            type: str = None,
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            tensor: Optional[TypeData] = None,
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            affine: Optional[TypeData] = None,
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            check_nans: bool = True,
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            num_spatial_dims: Optional[int] = None,
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            channels_last: Optional[bool] = None,
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            **kwargs: Dict[str, Any],
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            ):
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        self.check_nans = check_nans
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        self.num_spatial_dims = num_spatial_dims
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        if type is None:
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            warnings.warn(
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                'Not specifying the image type is deprecated and will be'
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                ' mandatory in the future. You can probably use ScalarImage or'
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                ' LabelMap instead'
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            )
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            type = INTENSITY
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        if path is None and tensor is None:
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            raise ValueError('A value for path or tensor must be given')
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        self._loaded = False
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        # Number of channels are typically stored in the last dimensions in disk
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        # But if a tensor is given, the channels should be in the first dim
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        if channels_last is None:
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            channels_last = path is not None
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        self.channels_last = channels_last
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        tensor = self.parse_tensor(tensor)
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        affine = self.parse_affine(affine)
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        if tensor is not None:
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            self[DATA] = tensor
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            self[AFFINE] = affine
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            self._loaded = True
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        for key in PROTECTED_KEYS:
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            if key in kwargs:
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                message = f'Key "{key}" is reserved. Use a different one'
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                raise ValueError(message)
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        super().__init__(**kwargs)
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        self.path = self._parse_path(path)
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        self[PATH] = '' if self.path is None else str(self.path)
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        self[STEM] = '' if self.path is None else get_stem(self.path)
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        self[TYPE] = type
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    def __repr__(self):
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        properties = []
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        if self._loaded:
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            properties.extend([
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                f'shape: {self.shape}',
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                f'spacing: {self.get_spacing_string()}',
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                f'orientation: {"".join(self.orientation)}+',
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                f'memory: {humanize.naturalsize(self.memory, binary=True)}',
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            ])
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        else:
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            properties.append(f'path: "{self.path}"')
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        properties.append(f'type: {self.type}')
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        properties = '; '.join(properties)
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        string = f'{self.__class__.__name__}({properties})'
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        return string
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    def __getitem__(self, item):
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        if item in (DATA, AFFINE):
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            if item not in self:
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                self._load()
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        return super().__getitem__(item)
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    def __array__(self):
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        return self[DATA].numpy()
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    def __copy__(self):
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        kwargs = dict(
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            tensor=self.data,
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            affine=self.affine,
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            type=self.type,
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            path=self.path,
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            channels_last=False,
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        )
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        for key, value in self.items():
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            if key in PROTECTED_KEYS: continue
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            kwargs[key] = value  # should I copy? deepcopy?
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        return self.__class__(**kwargs)
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    @property
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    def data(self):
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        return self[DATA]
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    @property
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    def tensor(self):
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        return self.data
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    @property
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    def affine(self):
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        return self[AFFINE]
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    @property
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    def type(self):
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        return self[TYPE]
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    @property
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    def shape(self) -> Tuple[int, int, int, int]:
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        return tuple(self.data.shape)
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    @property
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    def spatial_shape(self) -> TypeTripletInt:
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        return self.shape[1:]
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    @property
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    def orientation(self):
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        return nib.aff2axcodes(self.affine)
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    @property
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    def spacing(self):
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        _, spacing = get_rotation_and_spacing_from_affine(self.affine)
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        return tuple(spacing)
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    @property
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    def memory(self):
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        return np.prod(self.shape) * 4  # float32, i.e. 4 bytes per voxel
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    def get_spacing_string(self):
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        strings = [f'{n:.2f}' for n in self.spacing]
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        string = f'({", ".join(strings)})'
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        return string
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    @staticmethod
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    def _parse_path(path: TypePath) -> Path:
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        if path is None:
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            return None
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        try:
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            path = Path(path).expanduser()
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        except TypeError:
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            message = f'Conversion to path not possible for variable: {path}'
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            raise TypeError(message)
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        if not (path.is_file() or path.is_dir()):  # might be a dir with DICOM
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            raise FileNotFoundError(f'File not found: {path}')
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        return path
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    def parse_tensor(self, tensor: TypeData) -> torch.Tensor:
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        if tensor is None:
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            return None
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        if isinstance(tensor, np.ndarray):
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            tensor = torch.from_numpy(tensor.astype(np.float32))
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        elif isinstance(tensor, torch.Tensor):
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            tensor = tensor.float()
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        tensor = self.parse_tensor_shape(tensor)
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        if self.check_nans and torch.isnan(tensor).any():
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            warnings.warn(f'NaNs found in tensor')
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        return tensor
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    def parse_tensor_shape(self, tensor: torch.Tensor) -> torch.Tensor:
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        return ensure_4d(tensor, self.channels_last, self.num_spatial_dims)
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    @staticmethod
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    def parse_affine(affine: np.ndarray) -> np.ndarray:
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        if affine is None:
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            return np.eye(4)
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        if not isinstance(affine, np.ndarray):
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            raise TypeError(f'Affine must be a NumPy array, not {type(affine)}')
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        if affine.shape != (4, 4):
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            raise ValueError(f'Affine shape must be (4, 4), not {affine.shape}')
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        return affine
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    def _load(self) -> Tuple[torch.Tensor, np.ndarray]:
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        r"""Load the image from disk.
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        Returns:
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            Tuple containing a 4D tensor of size :math:`(C, D, H, W)` and a 2D
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            :math:`4 \times 4` affine matrix to convert voxel indices to world
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            coordinates.
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        """
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        if self._loaded:
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            return
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        tensor, affine = read_image(self.path)
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        tensor = self.parse_tensor_shape(tensor)
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        if self.check_nans and torch.isnan(tensor).any():
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            warnings.warn(f'NaNs found in file "{self.path}"')
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        self[DATA] = tensor
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        self[AFFINE] = affine
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        self._loaded = True
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    def save(self, path, squeeze=True, channels_last=True):
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        """Save image to disk.
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        Args:
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            path: String or instance of :py:class:`pathlib.Path`.
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            squeeze: If ``True``, the singleton dimensions will be removed
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                before saving.
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            channels_last: If ``True``, the channels will be saved in the last
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                dimension.
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        """
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        write_image(
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            self[DATA],
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            self[AFFINE],
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            path,
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            squeeze=squeeze,
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            channels_last=channels_last,
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        )
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    def is_2d(self) -> bool:
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        return self.shape[-3] == 1
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    def numpy(self) -> np.ndarray:
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        """Get a NumPy array containing the image data."""
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        return np.asarray(self)
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    def as_sitk(self) -> sitk.Image:
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        """Get the image as an instance of :py:class:`sitk.Image`."""
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        return nib_to_sitk(self[DATA], self[AFFINE])
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    def get_center(self, lps: bool = False) -> TypeTripletFloat:
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        """Get image center in RAS+ or LPS+ coordinates.
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        Args:
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            lps: If ``True``, the coordinates will be in LPS+ orientation, i.e.
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                the first dimension grows towards the left, etc. Otherwise, the
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                coordinates will be in RAS+ orientation.
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        """
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        size = np.array(self.spatial_shape)
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        center_index = (size - 1) / 2
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        r, a, s = nib.affines.apply_affine(self.affine, center_index)
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        if lps:
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            return (-r, -a, s)
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        else:
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            return (r, a, s)
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    def set_check_nans(self, check_nans: bool):
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        self.check_nans = check_nans
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    def crop(self, index_ini: TypeTripletInt, index_fin: TypeTripletInt):
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        new_origin = nib.affines.apply_affine(self.affine, index_ini)
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        new_affine = self.affine.copy()
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        new_affine[:3, 3] = new_origin
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        i0, j0, k0 = index_ini
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        i1, j1, k1 = index_fin
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        patch = self.data[:, i0:i1, j0:j1, k0:k1].clone()
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        kwargs = dict(
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            tensor=patch,
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            affine=new_affine,
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            type=self.type,
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            path=self.path,
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            channels_last=False,
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        )
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        for key, value in self.items():
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            if key in PROTECTED_KEYS: continue
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            kwargs[key] = value  # should I copy? deepcopy?
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        return self.__class__(**kwargs)
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class ScalarImage(Image):
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    """Alias for :py:class:`~torchio.Image` of type :py:attr:`torchio.INTENSITY`.
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    Example:
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        >>> import torch
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        >>> import torchio
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        >>> image = torchio.ScalarImage('t1.nii.gz')  # loading from a file
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        >>> image = torchio.ScalarImage(tensor=torch.rand(128, 128, 68))  # from tensor
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        >>> data, affine = image.data, image.affine
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        >>> affine.shape
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        (4, 4)
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        >>> image.data is image[torchio.DATA]
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        True
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        >>> image.data is image.tensor
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        True
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        >>> type(image.data)
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        torch.Tensor
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    See :py:class:`~torchio.Image` for more information.
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    Raises:
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        ValueError: A :py:attr:`type` is used for instantiation.
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    """
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    def __init__(self, *args, **kwargs):
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        if 'type' in kwargs and kwargs['type'] != INTENSITY:
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            raise ValueError('Type of ScalarImage is always torchio.INTENSITY')
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        kwargs.update({'type': INTENSITY})
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        super().__init__(*args, **kwargs)
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class LabelMap(Image):
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    """Alias for :py:class:`~torchio.Image` of type :py:attr:`torchio.LABEL`.
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    Example:
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        >>> import torch
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        >>> import torchio
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        >>> labels = torchio.LabelMap(tensor=torch.rand(128, 128, 68) > 0.5)
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        >>> labels = torchio.LabelMap('t1_seg.nii.gz')  # loading from a file
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    See :py:class:`~torchio.data.image.Image` for more information.
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    Raises:
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        ValueError: If a value for :py:attr:`type` is given.
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    """
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    def __init__(self, *args, **kwargs):
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        if 'type' in kwargs and kwargs['type'] != LABEL:
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            raise ValueError('Type of LabelMap is always torchio.LABEL')
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        kwargs.update({'type': LABEL})
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        super().__init__(*args, **kwargs)
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