Source code for torch_geometric.nn.models.deep_graph_infomax

import torch
from torch.nn import Parameter

from ..inits import reset, uniform

EPS = 1e-15

[docs]class DeepGraphInfomax(torch.nn.Module): r"""The Deep Graph Infomax model from the `"Deep Graph Infomax" <>`_ paper based on user-defined encoder and summary model :math:`\mathcal{E}` and :math:`\mathcal{R}` respectively, and a corruption function :math:`\mathcal{C}`. Args: hidden_channels (int): The latent space dimensionality. encoder (Module): The encoder module :math:`\mathcal{E}`. summary (callable): The readout function :math:`\mathcal{R}`. corruption (callable): The corruption function :math:`\mathcal{C}`. """ def __init__(self, hidden_channels, encoder, summary, corruption): super().__init__() self.hidden_channels = hidden_channels self.encoder = encoder self.summary = summary self.corruption = corruption self.weight = Parameter(torch.Tensor(hidden_channels, hidden_channels)) self.reset_parameters()
[docs] def reset_parameters(self): reset(self.encoder) reset(self.summary) uniform(self.hidden_channels, self.weight)
[docs] def forward(self, *args, **kwargs): """Returns the latent space for the input arguments, their corruptions and their summary representation.""" pos_z = self.encoder(*args, **kwargs) cor = self.corruption(*args, **kwargs) cor = cor if isinstance(cor, tuple) else (cor, ) neg_z = self.encoder(*cor) summary = self.summary(pos_z, *args, **kwargs) return pos_z, neg_z, summary
[docs] def discriminate(self, z, summary, sigmoid=True): r"""Given the patch-summary pair :obj:`z` and :obj:`summary`, computes the probability scores assigned to this patch-summary pair. Args: z (Tensor): The latent space. summary (Tensor): The summary vector. sigmoid (bool, optional): If set to :obj:`False`, does not apply the logistic sigmoid function to the output. (default: :obj:`True`) """ summary = summary.t() if summary.dim() > 1 else summary value = torch.matmul(z, torch.matmul(self.weight, summary)) return torch.sigmoid(value) if sigmoid else value
[docs] def loss(self, pos_z, neg_z, summary): r"""Computes the mutual information maximization objective.""" pos_loss = -torch.log( self.discriminate(pos_z, summary, sigmoid=True) + EPS).mean() neg_loss = -torch.log(1 - self.discriminate(neg_z, summary, sigmoid=True) + EPS).mean() return pos_loss + neg_loss
[docs] def test(self, train_z, train_y, test_z, test_y, solver='lbfgs', multi_class='auto', *args, **kwargs): r"""Evaluates latent space quality via a logistic regression downstream task.""" from sklearn.linear_model import LogisticRegression clf = LogisticRegression(solver=solver, multi_class=multi_class, *args, **kwargs).fit(train_z.detach().cpu().numpy(), train_y.detach().cpu().numpy()) return clf.score(test_z.detach().cpu().numpy(), test_y.detach().cpu().numpy())
def __repr__(self) -> str: return f'{self.__class__.__name__}({self.hidden_channels})'