decagon-pytorch/src/decagon_pytorch/convolve.py

import torch
from .dropout import dropout_sparse
from .weights import init_glorot


class SparseGraphConv(torch.nn.Module):
    """Convolution layer for sparse inputs."""
    def __init__(self, in_channels, out_channels,
        adjacency_matrix, **kwargs):
        super().__init__(**kwargs)
        self.in_channels = in_channels
        self.out_channels = out_channels
        self.weight = init_glorot(in_channels, out_channels)
        self.adjacency_matrix = adjacency_matrix


    def forward(self, x):
        x = torch.sparse.mm(x, self.weight)
        x = torch.sparse.mm(self.adjacency_matrix, x)
        return x


class SparseDropoutGraphConvActivation(torch.nn.Module):
    def __init__(self, input_dim, output_dim,
        adjacency_matrix, keep_prob=1.,
        activation=torch.nn.functional.relu,
        **kwargs):
        super().__init__(**kwargs)
        self.sparse_graph_conv = SparseGraphConv(input_dim, output_dim)
        self.keep_prob = keep_prob
        self.activation = activation

    def forward(self, x):
        x = dropout_sparse(x, self.keep_prob)
        x = self.sparse_graph_conv(x)
        x = self.activation(x)
        return x


class SparseMultiDGCA(torch.nn.Module):
    def __init__(self, input_dim, output_dim,
        adjacency_matrices, keep_prob=1.,
        activation=torch.nn.functional.relu,
        **kwargs):
        super().__init__(**kwargs)
        self.sparse_dgca =  [ SparseDropoutGraphConvActivation(input_dim, output_dim, adj_mat, keep_prob, activation) for adj_mat in adjacency_matrices ]

    def forward(self, x):
        out = torch.zeros(len(x), output_dim, dtype=x.dtype)
        for f in self.sparse_dgca:
            out += f(x)
        out = torch.nn.functional.normalize(out, p=2, dim=1)
        return out