Book Image

Python Data Cleaning Cookbook

By : Michael Walker
Book Image

Python Data Cleaning Cookbook

By: Michael Walker

Overview of this book

Getting clean data to reveal insights is essential, as directly jumping into data analysis without proper data cleaning may lead to incorrect results. This book shows you tools and techniques that you can apply to clean and handle data with Python. You'll begin by getting familiar with the shape of data by using practices that can be deployed routinely with most data sources. Then, the book teaches you how to manipulate data to get it into a useful form. You'll also learn how to filter and summarize data to gain insights and better understand what makes sense and what does not, along with discovering how to operate on data to address the issues you've identified. Moving on, you'll perform key tasks, such as handling missing values, validating errors, removing duplicate data, monitoring high volumes of data, and handling outliers and invalid dates. Next, you'll cover recipes on using supervised learning and Naive Bayes analysis to identify unexpected values and classification errors, and generate visualizations for exploratory data analysis (EDA) to visualize unexpected values. Finally, you'll build functions and classes that you can reuse without modification when you have new data. By the end of this Python book, you'll be equipped with all the key skills that you need to clean data and diagnose problems within it.
Table of Contents (12 chapters)

Chapter 5: Using Visualizations for the Identification of Unexpected Values

We dipped our toes in the water with visualizations in several recipes in the previous chapter. We used histograms and QQ plots to examine the distribution of a single variable, and scatter plots to view how two variables are related. But we were just scratching the surface of the rich visualization tools available in the Matplotlib and Seaborn libraries. Getting comfortable with these tools, and their seemingly inexhaustible capabilities, can help us uncover patterns and oddities that are not obvious when we run the standard battery of descriptives.

Boxplots, for example, are a great tool for visualizing values outside of a certain range. These can be extended with grouped boxplots or violin plots that allow us to compare distributions across subsets of data. We can also do much more with scatter plots than we did in the last chapter, including getting some sense of multivariate relationships. Histograms...