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User-item bipartite graph. LightGCN. PinSage. Message passing for recommendations. PyG implementation.

Recommendation Systems: From Basic to Production

Part 3: Advanced RecSys — Knowledge Graph, Multi-task & GNN

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Introduction

User-item bipartite graph. LightGCN. PinSage. Message passing for recommendations. PyG implementation.

1. Overview

Key concepts

Graph Neural Networks for Recommendation is an important topic in the field of modern AI.

2. Architecture & Principles

Core Architecture

# Example implementation
import torch
import torch.nn as nn

class ExampleModel(nn.Module):
    def __init__(self, input_dim, output_dim):
        super().__init__()
        self.net = nn.Sequential(
            nn.Linear(input_dim, 256),
            nn.ReLU(),
            nn.Dropout(0.2),
            nn.Linear(256, 128),
            nn.ReLU(),
            nn.Linear(128, output_dim),
        )
    
    def forward(self, x):
        return self.net(x)

3. Practice

Setup

pip install torch transformers datasets

Training Pipeline

# Training loop
model = ExampleModel(input_dim=768, output_dim=10)
optimizer = torch.optim.AdamW(model.parameters(), lr=1e-4)
criterion = nn.CrossEntropyLoss()

for epoch in range(10):
    for batch in train_loader:
        optimizer.zero_grad()
        outputs = model(batch["input"])
        loss = criterion(outputs, batch["label"])
        loss.backward()
        optimizer.step()

4. Best Practices

Aspect	Recommendation
Data	Quality over quantity
Model	Start simple, scale up
Training	Monitor loss curves
Evaluation	Use appropriate metrics

Summary

Concepts	Key Takeaway
Architecture	Suitable for the problem
Training	Careful hyperparameter tuning
Evaluation	Multiple metrics

Lesson 8: Graph Neural Networks for Recommendation