Book Image

The Data Wrangling Workshop - Second Edition

By : Brian Lipp, Shubhadeep Roychowdhury, Dr. Tirthajyoti Sarkar
Book Image

The Data Wrangling Workshop - Second Edition

By: Brian Lipp, Shubhadeep Roychowdhury, Dr. Tirthajyoti Sarkar

Overview of this book

While a huge amount of data is readily available to us, it is not useful in its raw form. For data to be meaningful, it must be curated and refined. If you’re a beginner, then The Data Wrangling Workshop will help to break down the process for you. You’ll start with the basics and build your knowledge, progressing from the core aspects behind data wrangling, to using the most popular tools and techniques. This book starts by showing you how to work with data structures using Python. Through examples and activities, you’ll understand why you should stay away from traditional methods of data cleaning used in other languages and take advantage of the specialized pre-built routines in Python. Later, you’ll learn how to use the same Python backend to extract and transform data from an array of sources, including the internet, large database vaults, and Excel financial tables. To help you prepare for more challenging scenarios, the book teaches you how to handle missing or incorrect data, and reformat it based on the requirements from your downstream analytics tool. By the end of this book, you will have developed a solid understanding of how to perform data wrangling with Python, and learned several techniques and best practices to extract, clean, transform, and format your data efficiently, from a diverse array of sources.
Table of Contents (11 chapters)

Useful Methods of Pandas

In this section, we will discuss some small utility functions that are offered by pandas so that we can work efficiently with DataFrames. They don't fall under any particular group of functions, so they are mentioned here under the Miscellaneous category. Let's discuss these miscellaneous methods in detail.

Randomized Sampling

In this section, we will discuss random sampling data from our DataFrames. This is a very common task in a variety of pipelines, one of which is machine learning. Sampling is often used in machine learning data-wrangling pipelines when choosing which data to train and which data to test against. Sampling a random fraction of a big DataFrame is often very useful so that we can practice other methods on them and test our ideas. If you have a database table of 1 million records, then it is not computationally effective to run your test scripts on the full table.

However, you may also not want to extract only the first...