Source code for monai.networks.layers.gmm

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# Licensed under the Apache License, Version 2.0 (the "License");
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import torch

from monai._extensions.loader import load_module

__all__ = ["GaussianMixtureModel"]

[docs]class GaussianMixtureModel: """ Takes an initial labeling and uses a mixture of Gaussians to approximate each classes distribution in the feature space. Each unlabeled element is then assigned a probability of belonging to each class based on it's fit to each classes approximated distribution. See: """ def __init__(self, channel_count: int, mixture_count: int, mixture_size: int, verbose_build: bool = False): """ Args: channel_count: The number of features per element. mixture_count: The number of class distributions. mixture_size: The number Gaussian components per class distribution. verbose_build: If ``True``, turns on verbose logging of load steps. """ if not torch.cuda.is_available(): raise NotImplementedError("GaussianMixtureModel is currently implemented for CUDA.") self.channel_count = channel_count self.mixture_count = mixture_count self.mixture_size = mixture_size self.compiled_extension = load_module( "gmm", {"CHANNEL_COUNT": channel_count, "MIXTURE_COUNT": mixture_count, "MIXTURE_SIZE": mixture_size}, verbose_build=verbose_build, ) self.params, self.scratch = self.compiled_extension.init() def reset(self): """ Resets the parameters of the model. """ self.params, self.scratch = self.compiled_extension.init() def learn(self, features, labels): """ Learns, from scratch, the distribution of each class from the provided labels. Args: features (torch.Tensor): features for each element. labels (torch.Tensor): initial labeling for each element. """ self.compiled_extension.learn(self.params, self.scratch, features, labels) def apply(self, features): """ Applies the current model to a set of feature vectors. Args: features (torch.Tensor): feature vectors for each element. Returns: output (torch.Tensor): class assignment probabilities for each element. """ return _ApplyFunc.apply(self.params, features, self.compiled_extension)
class _ApplyFunc(torch.autograd.Function): @staticmethod def forward(ctx, params, features, compiled_extension): return compiled_extension.apply(params, features) @staticmethod def backward(ctx, grad_output): raise NotImplementedError("GMM does not support backpropagation")