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)

Importing Excel files

The read_excel method of the pandas library can be used to import data from an Excel file and load it into memory as a pandas data frame. In this recipe, we import an Excel file and handle some common issues when working with Excel files: extraneous header and footer information, selecting specific columns, removing rows with no data, and connecting to particular sheets.

Despite the tabular structure of Excel, which invites the organization of data into rows and columns, spreadsheets are not datasets and do not require people to store data in that way. Even when some data conforms to those expectations, there is often additional information in rows or columns before or after the data to be imported. Data types are not always as clear as they are to the person who created the spreadsheet. This will be all too familiar to anyone who has ever battled with importing leading zeros. Moreover, Excel does not insist that all data in a column be of the same type, or...