Lesson Introduction

Hello! In this lesson, we're diving into a powerful technique in machine learning called Bagging. Bagging stands for Bootstrap Aggregating. Imagine making important decisions by averaging the opinions of a large group rather than relying on just one individual. This collaborative approach generally leads to better and more stable decisions. The idea behind all ensemble methods is to combine predictions from multiple models to produce a single prediction. Our goal is to understand Bagging, how it works, and how to implement it using Python's scikit-learn library.

Bagging is an ensemble method. It improves the stability and accuracy of machine learning models by training multiple copies of a dataset and combining their results. Think of it as working with a panel of experts rather than a single adviser.

How Bagging Works: An Example

Let's break it down with a simple example:

Suppose you have a dataset of different types of flowers and you want to classify them. Instead of training just one decision tree which might overfit to your training data, you can train multiple decision trees on different subsets of your data. Each subset is created by randomly selecting samples from the original dataset (with replacement) and has the same size as the original dataset. Then, you aggregate the predictions from all the trees. This process reduces overfitting and leads to a more robust model.

It is important to note that a decision tree is just an example. You can use any model with bagging.

Loading a Dataset and Splitting the Data

Let's start by loading a dataset. Think of it as a table of data where each row is an example we're learning from, and each column is a feature or quality about the examples. For today, we'll use a dataset about wine. This dataset comes with scikit-learn, so it's easy to load.

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