Book Image

Practical Data Wrangling

By : Allan Visochek
Book Image

Practical Data Wrangling

By: Allan Visochek

Overview of this book

Around 80% of time in data analysis is spent on cleaning and preparing data for analysis. This is, however, an important task, and is a prerequisite to the rest of the data analysis workflow, including visualization, analysis and reporting. Python and R are considered a popular choice of tool for data analysis, and have packages that can be best used to manipulate different kinds of data, as per your requirements. This book will show you the different data wrangling techniques, and how you can leverage the power of Python and R packages to implement them. You’ll start by understanding the data wrangling process and get a solid foundation to work with different types of data. You’ll work with different data structures and acquire and parse data from various locations. You’ll also see how to reshape the layout of data and manipulate, summarize, and join data sets. Finally, we conclude with a quick primer on accessing and processing data from databases, conducting data exploration, and storing and retrieving data quickly using databases. The book includes practical examples on each of these points using simple and real-world data sets to give you an easier understanding. By the end of the book, you’ll have a thorough understanding of all the data wrangling concepts and how to implement them in the best possible way.
Table of Contents (16 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Using the CSV module to read CSV data


In this first demonstration, you will read the artificial_roads_by_region.csv file and get an estimate of the total length of roads as of 2011.

The first step to using the CSV module is to import the module, as shown in the following example:

import csv

The next step, similar to the process use in Chapter 3Reading, Exploring, and Modifying Data - Part I, is to open the file containing the data. Recall that for this chapter, the code is one directory up from the base directory. This means that in the path to the data, you will first need to go back one directory using ../ in macOS and Linux or ..\\ in Windows. In the following demonstration, I've created a Python script called csv_intro.py in which the open() function is used to open artificial_roads_by_region.csv with read permission:

import csv

## open the file containing the data
fin = open("../data/input_data/artificial_roads_by_region.csv","r",newline="")

Note

You may have noticed that a new parameter...