AI Lesson 28 – Support Vector Machines(SVM) | Dataplexa

Support Vector Machines (SVM)

Support Vector Machines, commonly called SVMs, are powerful supervised machine learning algorithms used mainly for classification problems. They are known for their strong mathematical foundation and their ability to handle complex decision boundaries.

In this lesson, you will understand how SVM works, why it is effective, where it is used in real-world applications, and how to implement it using code.

Why Support Vector Machines?

Some classification problems cannot be solved well with simple linear boundaries. Data points may overlap or form complex patterns.

SVM is designed to find the best possible boundary that separates classes with maximum margin.

  • Works well with high-dimensional data
  • Effective even when data is not perfectly separable
  • Strong theoretical guarantees

What Is an SVM?

An SVM is a classifier that finds a hyperplane that best separates data points into different classes.

The goal is not just to separate classes, but to do so in a way that maximizes the distance between the nearest points of each class and the boundary.

Real-World Example

Imagine a bank deciding whether to approve or reject a loan. Customer data points belong to two classes: approved and rejected.

SVM finds the safest boundary that separates these two groups so future decisions are made with higher confidence.

Key Concepts in SVM

  • Hyperplane: The decision boundary separating classes
  • Margin: Distance between the hyperplane and nearest data points
  • Support Vectors: Data points closest to the boundary

Only support vectors influence the position of the boundary, which makes SVM efficient.

Linear vs Non-Linear SVM

When data can be separated using a straight line, linear SVM is used.

For complex patterns, SVM uses the kernel trick to transform data into higher dimensions where separation becomes possible.

Common Kernels

  • Linear Kernel
  • Polynomial Kernel
  • Radial Basis Function (RBF)
  • Sigmoid Kernel

Simple SVM Example (Conceptual)

The following code demonstrates how an SVM classifier can be trained using Python.


from sklearn import svm

# Sample data
X = [[1,2],[2,3],[3,3],[6,5],[7,7],[8,6]]
y = [0,0,0,1,1,1]

# Create SVM model
model = svm.SVC(kernel='linear')

# Train model
model.fit(X, y)

# Predict
prediction = model.predict([[4,4]])
print(prediction)
  
[1]

The model predicts that the new data point belongs to class 1. This decision is based on the optimal boundary learned from the data.

How SVM Makes Decisions

SVM evaluates where a new data point lies relative to the decision boundary.

If the point lies on one side, it belongs to class 0; if on the other side, it belongs to class 1.

Advantages of SVM

  • Effective in high-dimensional spaces
  • Robust against overfitting
  • Works well with small datasets

Limitations of SVM

  • Not suitable for very large datasets
  • Kernel selection can be tricky
  • Less interpretable compared to simpler models

Practice Questions

Practice 1: Which data points define the SVM boundary?



Practice 2: What does SVM try to maximize?



Practice 3: What technique allows SVM to handle non-linear data?



Quick Quiz

Quiz 1: What is the SVM decision boundary called?





Quiz 2: Which kernel is commonly used for non-linear SVM?





Quiz 3: SVM is mainly used for?





Coming up next: Decision Trees — intuitive models that make decisions using tree-like rules.