Machine Learning and Deep Learning Algorithm Trading, How to Build GANs Using TensorFlow 2

1. Introduction

In recent years, advances in artificial intelligence and machine learning technologies have made significant progress, and their importance is growing in the financial market, especially in the field of algorithmic trading. In this course, we will cover how to use a model of deep learning known as Generative Adversarial Network (GAN) to generate data and establish trading strategies based on that data. We will particularly provide a step-by-step guide on how to build a GAN using TensorFlow 2.

2. Basic Concepts of GAN

A GAN consists of two neural networks, namely the Generator and the Discriminator. The Generator creates fake data that looks like real data, while the Discriminator determines whether the data is real or generated by the Generator. These two neural networks compete against each other in learning, allowing the Generator to produce data that is more similar to the real data.

2.1. Structure of GAN

The basic structure of a GAN is as follows:

  • Generator: Takes a random noise vector as input and generates fake data.
  • Discriminator: Determines whether the input data is real or fake.

2.2. Learning Process of GAN

The learning process of a GAN generally involves the following steps:

  1. The Generator generates data from random noise.
  2. The Discriminator compares real data with data generated by the Generator.
  3. The Discriminator assigns a high score to data classified as real and a low score to fake data.
  4. Each neural network learns from each other through their loss functions.

3. Implementing GAN using TensorFlow 2

Now, let’s implement GAN using TensorFlow 2. In this process, we will explain the basic components of a GAN and explore how to apply it to financial data.

3.1. Environment Setup

Install TensorFlow 2 and other necessary libraries. You can install them using the following command:

pip install tensorflow numpy matplotlib

3.2. Loading Data

To obtain stock market data, public APIs like Yahoo Finance API can be used. Below is the method for loading and preprocessing the data.

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import yfinance as yf

# Load stock data
data = yf.download("AAPL", start="2010-01-01", end="2020-01-01")
data = data['Close'].values.reshape(-1, 1)
data = (data - np.mean(data)) / np.std(data)  # Normalization

3.3. Building GAN Model

Now it’s time to build the Generator and Discriminator of the GAN. Let’s implement a simple model using TensorFlow Keras API.

import tensorflow as tf
from tensorflow.keras import layers

# Generator model
def build_generator():
    model = tf.keras.Sequential()
    model.add(layers.Dense(128, activation='relu', input_shape=(100,)))
    model.add(layers.Dense(256, activation='relu'))
    model.add(layers.Dense(512, activation='relu'))
    model.add(layers.Dense(1, activation='tanh'))  # Stock data is normalized from -1 to 1
    return model

# Discriminator model
def build_discriminator():
    model = tf.keras.Sequential()
    model.add(layers.Dense(512, activation='relu', input_shape=(1,)))
    model.add(layers.Dense(256, activation='relu'))
    model.add(layers.Dense(1, activation='sigmoid'))
    return model

generator = build_generator()
discriminator = build_discriminator()

3.4. Training GAN

We will set up the necessary loss functions and optimizers to train the GAN and structure the training loop.

loss_fn = tf.keras.losses.BinaryCrossentropy()
generator_optimizer = tf.keras.optimizers.Adam(1e-4)
discriminator_optimizer = tf.keras.optimizers.Adam(1e-4)

# GAN training loop
def train_gan(epochs, batch_size):
    for epoch in range(epochs):
        for _ in range(batch_size):
            noise = np.random.normal(0, 1, size=(batch_size, 100))
            generated_data = generator(noise)

            idx = np.random.randint(0, data.shape[0], batch_size)
            real_data = data[idx]

            with tf.GradientTape() as disc_tape:
                real_output = discriminator(real_data)
                fake_output = discriminator(generated_data)

                disc_loss = loss_fn(tf.ones_like(real_output), real_output) + \
                            loss_fn(tf.zeros_like(fake_output), fake_output)

            gradients = disc_tape.gradient(disc_loss, discriminator.trainable_variables)
            discriminator_optimizer.apply_gradients(zip(gradients, discriminator.trainable_variables))

            with tf.GradientTape() as gen_tape:
                fake_output = discriminator(generated_data)
                gen_loss = loss_fn(tf.ones_like(fake_output), fake_output)

            gradients = gen_tape.gradient(gen_loss, generator.trainable_variables)
            generator_optimizer.apply_gradients(zip(gradients, generator.trainable_variables))

        if epoch % 100 == 0:
            print(f'Epoch {epoch} - Discriminator Loss: {disc_loss.numpy()} - Generator Loss: {gen_loss.numpy()}')

train_gan(epochs=10000, batch_size=32)

4. Analysis of GAN Results

After completing the training, we will visualize and analyze how similar the generated data is to the real data.

def plot_generated_data(generator, num_samples=1000):
    noise = np.random.normal(0, 1, size=(num_samples, 100))
    generated_data = generator(noise)

    plt.figure(figsize=(10, 5))
    plt.plot(generated_data, label='Generated Data')
    plt.plot(data[0:num_samples], label='Real Data')
    plt.legend()
    plt.show()

plot_generated_data(generator)

5. Conclusion

In this course, we explored how to generate stock market data using machine learning and deep learning-based Generative Adversarial Networks and how to develop potential trading strategies based on this data. GANs are effective for various data generation tasks and can be very useful in algorithmic trading. We recommend further exploring the possibilities in this field through more advanced models and techniques.

6. References