In this chapter, you'll be introduced to Hyper Text Markup Language (HTML), a declarative language used to structure modern websites. Using the rvest library, you'll learn how to query simple HTML elements and scrape your first table.

Introduction to HTML

Read in HTML

Beware of syntax errors!

Navigating HTML

Select all children of a list

Parse hyperlinks into a data frame

Scrape your first table

The right order of table elements

Turn a table into a data frame with html_table()

Introduction to HTML and Web Scraping

Cascading Style Sheets (CSS) describe how HTML elements are displayed on a web page, including colors, fonts, and general layout. In this chapter, you'll learn why CSS selectors and combinators are a crucial ingredient for web scraping.

Introduction to CSS

Select multiple HTML types

Order CSS selectors by the number of results

CSS classes and IDs

Identify the correct selector types

Leverage the uniqueness of IDs

Select the last child with a pseudo-class

CSS combinators

Select direct descendants with the child combinator

How many elements get returned?

Simply the best!

Not every sibling is the same

Navigation and Selection with CSS

The CSS selectors you got to know in the last chapter are powerful but have their limitations. For example, if you want to select nodes based on the properties of their descendants. XPath to the rescue! Using this query language, you can navigate and scrape even the most hideous HTML.

Introduction to XPATH

Find the correct CSS equivalent

Select by class and ID with XPATH

Use predicates to select nodes based on their children

XPATH functions and advanced predicates

Find a more elegant XPATH alternative

Get to know the position() function

Extract nodes based on the number of their children

The XPATH text() function

The shortcomings of html_table() with badly structured tables

Select directly from a parent element with XPATH's text()

Combine extracted data into a data frame

Scrape an element based on its text

Advanced Selection with XPATH

Now that you know how to extract content from web pages, it's time to look behind the curtains. In this final chapter, you’ll learn why HTTP requests are the foundation of every scraping action and how they can be customized to comply with best practices in web scraping.

Hakikat permintaan HTTP

Manakah pernyataan tentang HTTP berikut yang salah?

Lakukan dengan cara httr

Houston, kita mendapat 404!

Menyatakan identitas Anda dengan user agent kustom

Lihat user agent Anda

Tambahkan user agent kustom

Cara bersikap santun dan memperlambat permintaan Anda

Argumen kustom untuk fungsi yang ditahan lajunya

Terapkan throttling pada perayap multi-halaman

Rekap: Web Scraping di R

Scraping Best Practices

Pernahkah Anda menemukan situs web yang menampilkan banyak data seperti statistik, ulasan produk, atau harga dalam format yang tidak siap untuk analisis data? Sering kali, otoritas dan penyedia data lainnya menerbitkan data mereka dalam tabel yang tertata rapi. Namun, tidak semua situs tersebut menyertakan tombol unduh—jangan khawatir. Dalam kursus ini, Anda akan belajar cara mengumpulkan dan mengunduh data dari situs web mana pun dengan efisien menggunakan R. Anda akan mempelajari cara mengotomatiskan scraping dan parsing Wikipedia menggunakan paket rvest dan httr. Melalui latihan praktik, Anda juga akan memperluas pemahaman tentang HTML dan CSS, fondasi halaman web, sambil membuat alur kerja pengambilan data Anda lebih andal dan efisien.

Intermediate R

Introduction to the Tidyverse

Pelajari cara menggunakan R untuk mengumpulkan data dari situs web dan mengotomatisasi parsing Wikipedia.

Web Scraping di R

Pelajari cara mengumpulkan dan mengunduh data secara efisien dari situs web mana pun menggunakan R.

Manakah pernyataan tentang HTTP berikut yang salah?

Web Scraping di R

Latihan interaktif praktis