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Learning R Programming

You're reading from   Learning R Programming Language, tools, and practical techniques

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Product type Paperback
Published in Oct 2016
Publisher Packt
ISBN-13 9781785889776
Length 582 pages
Edition 1st Edition
Languages
Tools
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Author (1):
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Kun Ren Kun Ren
Author Profile Icon Kun Ren
Kun Ren
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Toc

Table of Contents (16) Chapters Close

Preface 1. Quick Start FREE CHAPTER 2. Basic Objects 3. Managing Your Workspace 4. Basic Expressions 5. Working with Basic Objects 6. Working with Strings 7. Working with Data 8. Inside R 9. Metaprogramming 10. Object-Oriented Programming 11. Working with Databases 12. Data Manipulation 13. High-Performance Computing 14. Web Scraping 15. Boosting Productivity

Learning XPath selectors

In the previous section, we learned about CSS selectors and how to use them as well as functions provided by the rvest package to extract contents from web pages.

CSS selectors are powerful enough to serve most needs of HTML node matching. However, sometimes an even more powerful technique is required to select nodes that meet more special conditions.

Take a look at the following web page a bit more complex than data/products.html:

Learning XPath selectors

This web page is stored as a standalone HTML file at data/new-products.html. The full source code is long we will only show the <body>. here. Please go through the source code to get an impression of its structure:

<body> 
  <h1>New Products</h1> 
  <p>The following is a list of products</p> 
  <div id="list" class="product-list"> 
    <ul> 
      <li> 
        <span class="name">Product-A</span> 
        <span class="price">$199...
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