Book Image

R Web Scraping Quick Start Guide

By : Olgun Aydin
Book Image

R Web Scraping Quick Start Guide

By: Olgun Aydin

Overview of this book

Web scraping is a technique to extract data from websites. It simulates the behavior of a website user to turn the website itself into a web service to retrieve or introduce new data. This book gives you all you need to get started with scraping web pages using R programming. You will learn about the rules of RegEx and Xpath, key components for scraping website data. We will show you web scraping techniques, methodologies, and frameworks. With this book's guidance, you will become comfortable with the tools to write and test RegEx and XPath rules. We will focus on examples of dynamic websites for scraping data and how to implement the techniques learned. You will learn how to collect URLs and then create XPath rules for your first web scraping script using rvest library. From the data you collect, you will be able to calculate the statistics and create R plots to visualize them. Finally, you will discover how to use Selenium drivers with R for more sophisticated scraping. You will create AWS instances and use R to connect a PostgreSQL database hosted on AWS. By the end of the book, you will be sufficiently confident to create end-to-end web scraping systems using R.
Table of Contents (7 chapters)

Exercises on RegEx and XPath

In this part, we are going to do some exercises that will be about writing XPaths and RegEx rules. For this purpose, we will use some open source tools.

One of the best open source platforms for practising writing RegEx rules is https://regex101.com/:

Regular expressions on regex101.com

As you see from the screenshot of regex101.com, the following is true:

  • You can add some text strings to the Test String part and you can add your regular expressions to the Regular Expression part.
  • On the Test String part, you will be able to see the matched strings.
  • For testing your XPath rules, you can use Google Chrome's developer tools.
  • You can reach this menu through the More Tools section; click on those three dots on your Chrome browser, as shown in the following screenshot:
Developer tools option on the web page
  • When you click Developer tools, you...