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By Tatev Aslanyan
"In God we trust; all others bring data." – W. Edwards Deming
This famous quote from Edwards Deming perfectly captures the essence of modern Data Science and AI.
Data is the lifeblood of Data Science and AI fields – Machine Learning, Deep Learning, Generative AI and much more. And understanding how to analyze and manipulate data it is key to unlocking its full potential.
The key to understanding all these concepts is linear algebra – the unsung hero behind many powerful algorithms and techniques.
If you've ever felt a disconnect between the linear algebra you learned in school and its practical use in your career, you're not alone. If you believe you should study and work your way through an entire book of Introduction to Linear Algebra, then you are again not alone.
Many aspiring data science and AI professionals struggle to bridge this gap and think they need to spend countless hours to master mathematics for Data Science and AI. But don't worry, this guide is here to help.
I'll show you how linear algebra isn't just a theoretical concept or old fashioned forgotten area of expertise. You'll learn how it's a practical tool that you can use to solve real-world problems in your field.
Linear Algebra combined with Mathematical Analysis (called Calculus I and II in many undergrad studies) form the backbone of Machine Learning, Deep Learning, Computer Vision, and Generative AI. From building recommendation systems and training Neural Networks to analyzing medical images, understanding linear algebra opens up a world of possibilities.
In this guide, you'll discover:
Whether you're a student, a recent graduate, or an experienced professional aspiring to become technical professional, this guide will equip you with the knowledge and skills to learn and leverage linear algebra effectively in your work. And you won't have to spend all your time on endless browsing and searching.
"Mathematics is like the producer of the movies: you don't see them but they are actually running the show." – Tatev Aslanyan
Let's dive into the heart of linear algebra and explore the core concepts that you will leverage daily in your Data Science, Machine Learning, or AI journey.
Think of vectors as lists of numbers (like NumPy arrays), and matrices as tables of numbers (multiple arrays stacked next to each other). In the world of data science and AI, vectors and matrices are your bread and butter.
Vectors can represent anything from customer characteristics (salary, age, height, income, purchase history) to word embeddings (numerical representations of words, text, and strings in general in natural language processing [NLP]). These vectors in datasets are commonly referred to as features – or, if used as response variables, as labels, dependent variables, and so on.
Matrices are powerful data structures that store datasets, with each row representing a data point and each column representing a feature. When you load your data and store it in a dataframe, all the rows of your data are basically the rows of your matrix, while all the features and response variables combined are the columns in your matrix.
Simple vector or matrix operations like addition, subtraction, multiplication of vectors and matrices are tools for data manipulation and transformation. These tools are used to normalize or standardize features, scale the data, combine different datasets or even perform forward pass/backward pass when training neural networks.
Linear algebra operations all power these common and daily tasks in Data Science and Machine Learning.
In the world of data, transformations are the key. You need transformations to rotate an image and resize it.
These are also common ways to perform data augmentation in Computer Vision. Maybe you want to adjust the colors or contrast. These tasks are all done through linear transformations, which are essentially functions that map one set of data points to another.
In the world of linear algebra, multiplying a matrix by a vector (or another matrix), transposing the matrix and inverting it, is like applying a specific transformation to your data. This is incredibly powerful for:
Think of eigenvalues and eigenvectors as the DNA of your data matrix. These sets of important values reveal the fundamental characteristics and directions, respectively, of largest variation (information).
Once you know the eigenvalues and eigenvectors, you can quickly figure out which features in your data contain the most variation (that is information). This is basically your golden ticket for feature selection.
Eigenvalues and eigenvectors are essential in linear algebra, as they offer insights into matrix properties. They are particularly useful across various disciplines such as engineering, physics, data science and AI.
Eigenvalues and Eigenvectors are essential for:
Don't be intimidated by the names – eigenvalues and eigenvectors are simply numbers and vectors that describe the inherent structure of your data. Understanding them gives you a powerful lens through which to analyze and interpret complex datasets.
Imagine a massive table of article ratings from thousands of users. Hidden within this data are patterns that reveal user preferences and article similarities.
Matrix factorization, particularly a technique called Singular Value Decomposition (SVD), is the key to creating such a recommender system.
SVD breaks down large matrices into smaller, more manageable matrices that reveal what are called latent factors. These are the underlying characteristics that explain why users rate things (like movies) the way they do. This is the algorithm behind famous recommendation systems like Amazon or Netflix, which use these latent factors to suggest items and movies you'll love.
But matrix factorization isn't just for building powerful recommender systems. It's a versatile tool used for:
Now let's look at a roadmap that'll help guide you as you master Linear Algebra for Data Science and AI. It's a structured journey that builds upon foundational concepts and progressively delves into advanced topics with real-world applications.
This roadmap, from LunarTechs 25+ hour Linear Algebra Course is aligned with resources such as the Linear Algebra and Its Applications by David C. Lay, Steven R. Lay,and Judi J. McDonald (Cambridge Linear Algebra Book) and the Interactive Linear Algebra by Dan Margalit and Joseph Rabinoff (UBC Linear Algebra Book). It provides you with a solid foundation to tackle real-world problems in data science and AI.
Image Source: LunarTech - Fundamentals to Linear Algebra
Here is the YouTube tutorial, Linear Algebra Roadmap 2024, which explains in even more detail the Linear Algebra Roadmap topic by topic.
By following this roadmap, you'll gain a comprehensive understanding of linear algebra concepts, starting from the basics and gradually progressing to advanced topics, equipping you with the skills necessary to tackle real-world problems in data science and AI.
Mathematics is like producer of the movies: you don't see them but they are actually running the show.
In this section, we'll delve into specific examples that showcase the practical power of linear algebra across various cutting edge fields. You'll see how seemingly abstract concepts translate into real-world solutions that drive innovation and impact our daily lives.
Let's explore how linear algebra is revolutionizing many different industries.
Linear Regression, which is a fundamental ML algorithm, relies on linear algebra to find the best-fit line (or hyperplane) that minimizes the error between predicted and actual values.
Matrices and vectors are used to represent data and model parameters, while matrix operations like inversion and transpose are crucial for solving the regression equations.
Application - House Price Prediction: Predicting housing prices based on features like square footage, number of bedrooms, and location. You can check out a complete end-to-end case study here.
Imagine you're a real estate agent trying to predict the price of a house. You have data on various features of different houses: the square footage, the number of bedrooms, and so on.
These features are put into a table-like structure called a matrix, denoted as X. Each row of X represents a different house, and each column represents a specific feature – for instance, one column might be the square footage, another the number of bedrooms. The prices of the corresponding houses are stored in another matrix, Y.
Your goal is to predict the price (Y) of a new house based on its features (X). Linear regression uses linear algebra to find the relationship between these features and the price.
The "line of best fit" is defined by a set of coefficients called Beta (β). Each element in Beta corresponds to a particular feature in X and tells you how much that feature influences the final price. We also add an error term, epsilon (ε), to account for any random variation in house prices that can't be explained by the features we have.
Under the hood, linear regression uses matrix operations like transposes, inverses, and matrix multiplication to calculate the Beta values that give the best prediction. So, while you might not see the complex math directly, linear algebra is the engine that powers the price estimates you see on real estate websites!
This algorithm uses linear algebra to model the relationship between customer features (like tenure, usage patterns, and demographics) and the probability of churn. Coefficients learned through linear algebra determine the importance of each feature in predicting churn.
Application - Customer Churn Prediction: A telecommunications company might use logistic regression to identify customers at high risk of switching to a competitor. The model analyzes factors like call duration, data usage, customer service interactions, and billing issues.
SVM is a powerful classification algorithm that uses linear algebra to find the optimal hyperplane separating different classes of data. The concept of vector dot products is central to calculating distances and determining the margin between classes.
Application - Spam Email Identification: classifies emails as spam or not spam based on features like word frequency and email length.
Techniques like Principal Component Analysis (PCA) leverage linear algebra to extract the most important features from image data, reducing dimensionality and improving computational efficiency.
Application - Object Detection: Object detection algorithms often use PCA to reduce the complexity of image features before classification.
PCA leverages linear algebra, specifically eigenvalues and eigenvectors, to identify the directions of greatest variance in high-dimensional data. By projecting data onto these principal components, PCA reduces dimensionality while preserving the most important information.
Application - Genomics: In genomics research, PCA is used to analyze gene expression data from thousands of genes. By reducing the dimensionality of the data, researchers can more easily visualize patterns and identify relationships between genes.
The foundation of deep learning, neural networks are essentially interconnected layers of nodes (neurons) that process information using linear algebra operations. Matrices represent weights and biases, while matrix multiplication and activation functions propagate signals through the network.
Application - Image Classification with CNNs: Image classification using convolutional neural networks (CNNs), where linear algebra is used for filtering operations and feature extraction.
Linear algebra is used extensively for image manipulation, including rotation, scaling, translation, and shearing. Matrices are used to represent these transformations, and matrix multiplication is used to apply them to images.
Application in Facial Recognition: Facial recognition software uses linear transformations to align and normalize face images for comparison.
GANs, a type of generative model, use linear algebra operations within their neural networks to learn and generate new data samples, such as images or text.
Application in Generating Images: Generating realistic images of human faces or creating artwork in the style of famous painters.
These generative models use linear algebra to encode high-dimensional data into a lower-dimensional latent space. This space is structured to follow a standard distribution (usually a Gaussian), making it easier to sample new data points and generate diverse outputs. Matrix operations are crucial for encoding and decoding data between the original space and the latent space.
Application in Healthcare with VAE: A pharmaceutical company uses VAEs to generate novel molecular structures with desired properties. By encoding existing drug molecules into a latent space, the VAE can explore this space to generate new candidate molecules that potentially have therapeutic effects.
All these examples are just the tip of the iceberg. Linear algebra plays an important role in countless applications across data science and AI. By understanding its core concepts, you'll be equipped to not only use existing algorithms but also contribute to the development of new and innovative solutions.
I often get asked about the best resources for learning linear algebra and specifically what book to read to master it. My advice, as someone who's gone through the traditional academic route of textbooks and countless theoretical examples: don't feel obligated to read those massive linear algebra textbooks cover to cover.
They are valuable resources, but not the most efficient way to learn if your goal is to apply linear algebra in your data science career.
Instead, focus on a clear, guided, and time-efficient approach to learning the theory that you'll actually use. Then, prioritize practical application: learn how to implement these concepts in Python and utilize them in machine learning, deep learning, and other areas. This is a far more effective use of your time.
So, where should you start? The answer is to understand the essentials and implement these concepts with clear guidance. This will help save your time and make it easier to learn effectively.
First of all, make sure you read through the roadmap and watch the accompanying video that I included above. And then you can move on to the following:
If you're overwhelmed by dense textbooks or endless theoretical examples, you're not alone. Linear algebra can be intimidating, but it's a crucial foundation for anyone working in data science and AI.
LunarTech's concise, career-focused course will equip you with the skills you need to excel in data science and AI. Try it now – it's included in our LunarTech Max plan at the moment. You can sign up for the Fundamentals of Linear Algebra 25+h Course here.
Source: Fundamentals to Linear Algebra 25+h Course
Whether you're a student looking for a clear and concise approach to linear algebra or a professional aiming to advance your career in AI and data science, this course will equip you with the knowledge and skills you need to succeed.
This shorter, demo version of the main course is perfect for learners who need a quick yet comprehensive overview of the key concepts in linear algebra. It’s great as a refresher or for those who need to understand the basics before diving into more complex topics, and is a starting point to learn Linear Algebra.
You can also check out this free freeCodeCamp course that covers key Linear Algebra topics like Gaussian reduction, vector spaces, linear maps, determinants, and eigenvalues and eigenvectors. There are many practical examples, and the course encourages you to work through each of them to solidify your knowledge.
There's also a link to download the professor's textbook if you're interested in that.
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Thank you for choosing this guide as your learning companion. As you continue to explore the vast field of machine learning, I hope you do so with confidence, precision, and an innovative spirit. Best wishes in all your future endeavors!
