Deep Learning with PyTorch (9-Day Mini-Course)

Deep learning is an intriguing field that yields impressive results across various complex machine learning challenges. However, getting started can be daunting. Questions often arise about which library to choose and which techniques to focus on.

In this 9-part crash course, you will explore applied deep learning using Python and the powerful PyTorch library. This mini-course is designed for practitioners who are already comfortable programming in Python and have a basic understanding of machine learning concepts. Let’s get started!

Overview

This mini-course consists of 9 lessons, each designed to take approximately 30 minutes to complete. You can progress through the material at your own pace—it’s recommended to tackle one lesson each day over the course of nine days.

The topics covered in this mini-course include:

1. Introduction to PyTorch.
2. Building Your First Multilayer Perceptron Model.
3. Training a PyTorch Model.
4. Using a PyTorch Model for Inference.
5. Loading Data from Torchvision.
6. Utilizing PyTorch DataLoader.
7. Convolutional Neural Networks (CNNs).
8. Training an Image Classifier.
9. Training with GPU support.

Prepare for an engaging and informative experience, as some reading, research, and programming are involved. This will help you effectively learn deep learning.

Who Is This Mini-Course For?

To ensure this course is right for you, check the following guidelines:

• You should be familiar with Python coding—basic installation of packages and script writing should be second nature to you. You don’t need to be an expert coder, but you should be comfortable navigating an experimental coding environment.
• You should have a foundational understanding of machine learning concepts, such as cross-validation, algorithms, and the bias-variance trade-off. You do not need to be a PhD in machine learning but should know where to find information if needed.

This mini-course isn’t intended to serve as a textbook on deep learning. Instead, it will take you from basic knowledge of machine learning in Python to effectively utilizing the power of deep learning in your projects.

Mini-Course Content

The mini-course is structured into the following parts:

1. How to Install PyTorch

In this section, you will learn about what PyTorch is, how to install it, and how to confirm the installation is successful.

What Are Torch and PyTorch?
PyTorch is an open-source Python library developed by Facebook for deep learning applications. It originated from the earlier Torch 7 library, which was primarily written in C and utilized through a Lua interface. PyTorch brings this framework into the Python ecosystem, making it accessible and user-friendly.

The PyTorch API is flexible and straightforward, appealing to both academics and practitioners alike. It is widely used across various domains, including text processing, computer vision, and audio data.

How to Install PyTorch:
To install PyTorch, ensure you have Python 3.6 or higher. If not, consider using Anaconda. The easiest way to install PyTorch on your system is through the pip command. You can use the following command:

pip install torch torchvision

For guidance tailored to your operating system, refer to the PyTorch Installation Guide.

Confirming Installation:
Once installed, it’s important to check if PyTorch is properly set up. Create a file named check_pytorch.py and add:

import torch
print(torch.__version__)

Run the script using:

python check_pytorch.py

Successful installation will display the installed version.

2. Preparing Your Data

This step involves loading and preparing your dataset for training. Deep learning models require numerical input, so you may need to preprocess your data using libraries like Pandas.

Example of a custom dataset class in PyTorch:

from torch.utils.data import Dataset

class CSVDataset(Dataset):
    def __init__(self, path):
        df = read_csv(path, header=None)
        self.X = df.values[:, :-1]
        self.y = df.values[:, -1]
        self.X = self.X.astype('float32')
        self.y = LabelEncoder().fit_transform(self.y).astype('float32')

    def __len__(self):
        return len(self.X)

    def __getitem__(self, idx):
        return [self.X[idx], self.y[idx]]

After creating your dataset class, you can use PyTorch’s DataLoader for efficient data handling.

3. Defining the Model

The next step is to define your neural network model, which can be accomplished by creating a class that extends nn.Module. Here is an example of a simple Multilayer Perceptron (MLP):

import torch.nn as nn

class MLP(nn.Module):
    def __init__(self, input_size):
        super(MLP, self).__init__()
        self.hidden1 = nn.Linear(input_size, 10)
        self.activation1 = nn.ReLU()
        self.hidden2 = nn.Linear(10, 1)
        self.activation2 = nn.Sigmoid()

    def forward(self, x):
        x = self.activation1(self.hidden1(x))
        x = self.activation2(self.hidden2(x))
        return x

4. Training the Model

In this phase, you will set the loss function and optimization algorithm. Common loss functions include:

• BCELoss for binary classification.
• CrossEntropyLoss for multi-class classification.

For optimization, you can use stochastic gradient descent or variants like Adam.

Example training loop:

for epoch in range(num_epochs):
    model.train()
    for inputs, targets in train_loader:
        optimizer.zero_grad()
        predictions = model(inputs)
        loss = criterion(predictions, targets)
        loss.backward()
        optimizer.step()

5. Evaluate the Model

Once trained, use the test dataset to evaluate the model’s performance:

model.eval()
with torch.no_grad():
    for inputs, targets in test_loader:
        predictions = model(inputs)
        # Calculate metrics

Conclusion

In this mini-course, you have gained foundational insights into deep learning with PyTorch. You learned how to install PyTorch, prepare your data, define models, and carry out training and evaluation. The concepts discussed will empower you to effectively develop and implement deep learning solutions in your projects.

Summary

This tutorial provided a comprehensive guide to developing deep learning models using PyTorch. Specifically, you learned:

• The differences between Torch and PyTorch.
• Steps to install and validate your PyTorch installation.
• The life cycle of a deep learning model in PyTorch, including data preparation, model definition, training, evaluation, and prediction.

By practicing these skills, you will be better equipped to undertake projects in deep learning using Python and PyTorch.