Book Image

Hands-On Data Preprocessing in Python

By : Roy Jafari
5 (2)
Book Image

Hands-On Data Preprocessing in Python

5 (2)
By: Roy Jafari

Overview of this book

Hands-On Data Preprocessing is a primer on the best data cleaning and preprocessing techniques, written by an expert who’s developed college-level courses on data preprocessing and related subjects. With this book, you’ll be equipped with the optimum data preprocessing techniques from multiple perspectives, ensuring that you get the best possible insights from your data. You'll learn about different technical and analytical aspects of data preprocessing – data collection, data cleaning, data integration, data reduction, and data transformation – and get to grips with implementing them using the open source Python programming environment. The hands-on examples and easy-to-follow chapters will help you gain a comprehensive articulation of data preprocessing, its whys and hows, and identify opportunities where data analytics could lead to more effective decision making. As you progress through the chapters, you’ll also understand the role of data management systems and technologies for effective analytics and how to use APIs to pull data. By the end of this Python data preprocessing book, you'll be able to use Python to read, manipulate, and analyze data; perform data cleaning, integration, reduction, and transformation techniques, and handle outliers or missing values to effectively prepare data for analytic tools.
Table of Contents (24 chapters)
1
Part 1:Technical Needs
6
Part 2: Analytic Goals
11
Part 3: The Preprocessing
18
Part 4: Case Studies

K-Means algorithm

K-Means is a random-based heuristic clustering algorithm. Random-based means that the output of the algorithm on the same data may be different on every run, while heuristic means that the algorithm does not reach the optimal solution. However, from experience, we know that it reaches a good solution.

K-Means clusters the data objects using a simple loop. The following diagram shows the steps that the algorithm performs, as well as the loop that heuristically finds the clusters in the data:

Figure 8.4 – K-Means flowchart

As we can see, the algorithm starts by randomly selecting k data objects as the cluster centroids. Then, the data objects are assigned to the cluster that is closest to its centroid. Next, the centroids are updated via the mean of all the data objects in the clusters. As the centroids are updated, the data objects are reassigned to the cluster that is closest to its centroid. Now, as the clusters are updated, the...