Source code for pygod.nn.gaan

import math
import torch
import torch.nn.functional as F
from torch_geometric.nn import MLP
from torch_geometric.utils import to_dense_adj

from ..nn.functional import double_recon_loss

[docs]class GAANBase(torch.nn.Module): """ Generative Adversarial Attributed Network Anomaly Detection GAAN is a generative adversarial attribute network anomaly detection framework, including a generator module, an encoder module, a discriminator module, and uses anomaly evaluation measures that consider sample reconstruction error and real sample recognition confidence to make predictions. This model is transductive only. See :cite:`chen2020generative` for details. Parameters ---------- in_dim : int Input dimension of the node features. noise_dim : int, optional Input dimension of the Gaussian random noise. Defaults: ``16``. hid_dim : int, optional Hidden dimension of model. Default: ``64``. num_layers : int, optional Total number of layers in model. A half (floor) of the layers are for the generator, the other half (ceil) of the layers are for encoder. Default: ``4``. dropout : float, optional Dropout rate. Default: ``0.``. act : callable activation function or None, optional Activation function if not None. Default: ``torch.nn.functional.relu``. **kwargs Other parameters for the backbone. """ def __init__(self, in_dim, noise_dim, hid_dim=64, num_layers=4, dropout=0., act=torch.nn.functional.relu, **kwargs): super(GAANBase, self).__init__() # split the number of layers for the encoder and decoders assert num_layers >= 2, \ "Number of layers must be greater than or equal to 2." generator_layers = math.floor(num_layers / 2) encoder_layers = math.ceil(num_layers / 2) self.generator = MLP(in_channels=noise_dim, hidden_channels=hid_dim, out_channels=in_dim, num_layers=generator_layers, dropout=dropout, act=act, **kwargs) self.discriminator = MLP(in_channels=in_dim, hidden_channels=hid_dim, out_channels=hid_dim, num_layers=encoder_layers, dropout=dropout, act=act, **kwargs) self.emb = None self.score_func = double_recon_loss
[docs] def forward(self, x, noise): """ Forward computation. Parameters ---------- x : torch.Tensor Input attribute embeddings. noise : torch.Tensor Input noise. Returns ------- x_ : torch.Tensor Reconstructed node features. a : torch.Tensor Reconstructed adjacency matrix from real samples. a_ : torch.Tensor Reconstructed adjacency matrix from fake samples. """ x_ = self.generator(noise) self.emb = self.discriminator(x) z_ = self.discriminator(x_) a = torch.sigmoid((self.emb @ self.emb.T)) a_ = torch.sigmoid((z_ @ z_.T)) return x_, a, a_
@staticmethod def loss_func_g(a_): loss_g = F.binary_cross_entropy(a_, torch.ones_like(a_)) return loss_g @staticmethod def loss_func_ed(a, a_): loss_r = F.binary_cross_entropy(a, torch.ones_like(a)) loss_f = F.binary_cross_entropy(a_, torch.zeros_like(a_)) return (loss_f + loss_r) / 2
[docs] @staticmethod def process_graph(data): """ Obtain the dense adjacency matrix of the graph. Parameters ---------- data : Input graph. """ data.s = to_dense_adj(data.edge_index)[0]