src/model.py

import torch
import torch.nn as nn
from torch_geometric.nn import GINConv, global_add_pool, global_mean_pool
import torch.nn.functional as F
import numpy as np


class GIN(torch.nn.Module):
    def __init__(self, num_features, num_classes, dropout, hidden_dim=128, num_layers=5, add_or_mean="add"):
        super().__init__()
        self.num_layers = num_layers
        self.hidden_dim = hidden_dim
        self.add_or_mean = add_or_mean
        self.dropout = dropout

        self.conv_layers = nn.ModuleList()

        # input features → hidden_dim
        mlp = nn.Sequential(
            nn.Linear(num_features, hidden_dim),
            nn.ReLU(),
            nn.Linear(hidden_dim, hidden_dim),
            nn.BatchNorm1d(hidden_dim)
        )
        self.conv_layers.append(GINConv(mlp, train_eps=True))

        # hidden GIN layers
        for _ in range(num_layers - 1):
            mlp = nn.Sequential(
                nn.Linear(hidden_dim, hidden_dim),
                nn.ReLU(),
                nn.Linear(hidden_dim, hidden_dim),
                nn.BatchNorm1d(hidden_dim)
            )
            self.conv_layers.append(GINConv(mlp, train_eps=True))

        # Final classifier (after pooling)
        self.fc = nn.Linear(hidden_dim, num_classes)

    def forward(self, x, edge_index, batch):
        for conv in self.conv_layers:
            x = conv(x, edge_index)
            x = F.relu(x)
            x = F.dropout(x, p=self.dropout, training=self.training)
        # Pool to get graph-level representation
        if self.add_or_mean == "mean":
            x = global_mean_pool(x, batch)
        elif self.add_or_mean == "add":
            x = global_add_pool(x, batch)

        x = F.dropout(x, p=0.5, training=self.training)
        return self.fc(x)