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Web Scraping Using R



rvest is new package that makes it easy to scrape (or harvest) data from html web pages, inspired by libraries like beautiful soup. It is designed to work with magrittr so that you can express complex operations as elegant pipelines composed of simple, easily understood pieces. Install it with:

rvest in action

Web scraping using rpa

Feb 13, 2019 Next, I created a URL link set-up feature (propertyurl) using htmlattr (“href”) which will tell Rstudio to read the URL and proceed to the next page and continue web scraping with the ‘For. How to automatically web scrape periodically so you can analyze timely/frequently updated data.There are many blogs and tutorials that teach you how to scrap.

To see rvest in action, imagine we’d like to scrape some information about The Lego Movie from IMDB. We start by downloading and parsing the file with html():

To extract the rating, we start with selectorgadget to figure out which css selector matches the data we want: strong span. (If you haven’t heard of selectorgadget, make sure to read vignette('selectorgadget') - it’s the easiest way to determine which selector extracts the data that you’re interested in.) We use html_node() to find the first node that matches that selector, extract its contents with html_text(), and convert it to numeric with as.numeric():

Web Scraping Using Regex

We use a similar process to extract the cast, using html_nodes() to find all nodes that match the selector:

Web Scraping Using Requests

The titles and authors of recent message board postings are stored in a the third table on the page. We can use html_node() and [[ to find it, then coerce it to a data frame with html_table():

Other important functions

Web Scraping Using R

  • If you prefer, you can use xpath selectors instead of css: html_nodes(doc, xpath = '//table//td')).

  • Extract the tag names with html_tag(), text with html_text(), a single attribute with html_attr() or all attributes with html_attrs().

  • Detect and repair text encoding problems with guess_encoding() and repair_encoding().

  • Navigate around a website as if you’re in a browser with html_session(), jump_to(), follow_link(), back(), and forward(). Extract, modify and submit forms with html_form(), set_values() and submit_form(). (This is still a work in progress, so I’d love your feedback.)

Automated Web Scraping Tool

To see these functions in action, check out package demos with demo(package = 'rvest').