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    )AnyLiteralOptionalUnion)Tensornn)_LPIPS)GeneratorType*_perceptual_path_length_validate_arguments_validate_generator_modelperceptual_path_length)Metric)_TORCHVISION_AVAILABLEPerceptualPathLengthc                       s   e Zd ZU dZdZeed< dZee ed< dZ	eed< e
jed< dZeed< 				
						d&dedededed dedee dee dee dee
jed f deddf fdd Zd!eddfd"d#Zdeeeef fd$d%Z  ZS )'r   a  Computes the perceptual path length (`PPL`_) of a generator model.

    The perceptual path length can be used to measure the consistency of interpolation in latent-space models. It is
    defined as

    .. math::
        PPL = \mathbb{E}\left[\frac{1}{\epsilon^2} D(G(I(z_1, z_2, t)), G(I(z_1, z_2, t+\epsilon)))\right]

    where :math:`G` is the generator, :math:`I` is the interpolation function, :math:`D` is a similarity metric,
    :math:`z_1` and :math:`z_2` are two sets of latent points, and :math:`t` is a parameter between 0 and 1. The metric
    thus works by interpolating between two sets of latent points, and measuring the similarity between the generated
    images. The expectation is approximated by sampling :math:`z_1` and :math:`z_2` from the generator, and averaging
    the calculated distanced. The similarity metric :math:`D` is by default the `LPIPS`_ metric, but can be changed by
    setting the `sim_net` argument.

    The provided generator model must have a `sample` method with signature `sample(num_samples: int) -> Tensor` where
    the returned tensor has shape `(num_samples, z_size)`. If the generator is conditional, it must also have a
    `num_classes` attribute. The `forward` method of the generator must have signature `forward(z: Tensor) -> Tensor`
    if `conditional=False`, and `forward(z: Tensor, labels: Tensor) -> Tensor` if `conditional=True`. The returned
    tensor should have shape `(num_samples, C, H, W)` and be scaled to the range [0, 255].

    .. hint::
        Using this metric with the default feature extractor requires that ``torchvision`` is installed.
        Either install as ``pip install torchmetrics[image]`` or ``pip install torchvision``

    As input to ``forward`` and ``update`` the metric accepts the following input

    - ``generator`` (:class:`~torch.nn.Module`):  Generator model, with specific requirements. See above.

    As output of `forward` and `compute` the metric returns the following output

    - ``ppl_mean`` (:class:`~torch.Tensor`): float scalar tensor with mean PPL value over distances
    - ``ppl_std`` (:class:`~torch.Tensor`): float scalar tensor with std PPL value over distances
    - ``ppl_raw`` (:class:`~torch.Tensor`): float scalar tensor with raw PPL distances

    Args:
        num_samples: Number of samples to use for the PPL computation.
        conditional: Whether the generator is conditional or not (i.e. whether it takes labels as input).
        batch_size: Batch size to use for the PPL computation.
        interpolation_method: Interpolation method to use. Choose from 'lerp', 'slerp_any', 'slerp_unit'.
        epsilon: Spacing between the points on the path between latent points.
        resize: Resize images to this size before computing the similarity between generated images.
        lower_discard: Lower quantile to discard from the distances, before computing the mean and standard deviation.
        upper_discard: Upper quantile to discard from the distances, before computing the mean and standard deviation.
        sim_net: Similarity network to use. Can be a `nn.Module` or one of 'alex', 'vgg', 'squeeze', where the three
            latter options correspond to the pretrained networks from the `LPIPS`_ paper.
        kwargs: Additional keyword arguments, see :ref:`Metric kwargs` for more info.

    Raises:
        ModuleNotFoundError:
            If ``torch-fidelity`` is not installed.
        ValueError:
            If ``num_samples`` is not a positive integer.
        ValueError:
            If `conditional` is not a boolean.
        ValueError:
            If ``batch_size`` is not a positive integer.
        ValueError:
            If ``interpolation_method`` is not one of 'lerp', 'slerp_any', 'slerp_unit'.
        ValueError:
            If ``epsilon`` is not a positive float.
        ValueError:
            If ``resize`` is not a positive integer.
        ValueError:
            If ``lower_discard`` is not a float between 0 and 1 or None.
        ValueError:
            If ``upper_discard`` is not a float between 0 and 1 or None.

    Example::
        >>> import torch
        >>> class DummyGenerator(torch.nn.Module):
        ...    def __init__(self, z_size) -> None:
        ...       super().__init__()
        ...       self.z_size = z_size
        ...       self.model = torch.nn.Sequential(torch.nn.Linear(z_size, 3*128*128), torch.nn.Sigmoid())
        ...    def forward(self, z):
        ...       return 255 * (self.model(z).reshape(-1, 3, 128, 128) + 1)
        ...    def sample(self, num_samples):
        ...      return torch.randn(num_samples, self.z_size)
        >>> generator = DummyGenerator(2)
        >>> ppl = PerceptualPathLength(num_samples=10)
        >>> ppl(generator)
        (tensor(...), tensor(...), tensor([...]))

    Fis_differentiableThigher_is_betterfull_state_updatenetfeature_network'     lerp-C6?@   {Gz?Gz?vggnum_samplesconditional
batch_sizeinterpolation_method)r   	slerp_any
slerp_unitepsilonresizelower_discardupper_discardsim_netalexr   squeezekwargsreturnNc
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 tstdt|||||||| || _|| _|| _|| _|| _	|| _
|| _|| _t|	tjr=|	| _d S |	dv rKtd|	|d| _d S td|	 )NzMetric `PerceptualPathLength` requires torchvision which is not installed.Install with `pip install torchvision` or `pip install torchmetrics[image]`r(   T)
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zPerceptualPathLength.__init__	generatorc                 C   s   t || j || _dS )zUpdate the generator model.N)r   r   r9   )r5   r9   r.   r.   r8   update   s   
zPerceptualPathLength.updatec                 C   s0   t | j| j| j| j| j| j| j| j| j	| j
d
S )z#Compute the perceptual path length.)
r9   r   r   r    r#   r$   r%   r&   r'   device)r   r9   r   r   r    r#   r$   r%   r&   r   r;   )r5   r.   r.   r8   compute   s   zPerceptualPathLength.compute)	r   Fr   r   r   r   r   r   r   )__name__
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& N)typingr   r   r   r   torchr   r   #torchmetrics.functional.image.lpipsr   4torchmetrics.functional.image.perceptual_path_lengthr	   r
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