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

Missing values

Missing values, as the name suggests, are values we expect to have but we don't. In the simplest terms, missing values are empty cells in a dataset that we want to use for analytic goals. For example, the following screenshot shows an example of a dataset with missing values—the first and third students' grade point average (GPA) is missing, the fifth student's height is missing, and the sixth student's personality type is missing:

Figure 11.1 – A dataset example with missing values

In Python, missing values are not presented with emptiness—they are presented via NaN, which is short for Not a Number. While the literal meaning of Not a Number does not completely capture all the possible situations for which we have missing values, NaN is used in Python whenever we have missing values.

The following screenshot shows a pandas DataFrame that has read and presented the table represented in Figure 11.1...