rvest helps you scrape information from web pages. It is designed to work with magrittr to make it easy to express common web scraping tasks, inspired by libraries like beautiful soup.
library(rvest)
lego_movie <- read_html("http://www.imdb.com/title/tt1490017/")
rating <- lego_movie %>%
html_nodes("strong span") %>%
html_text() %>%
as.numeric()
rating
#> [1] 7.8
cast <- lego_movie %>%
html_nodes("#titleCast .itemprop span") %>%
html_text()
cast
#> [1] "Will Arnett" "Elizabeth Banks" "Craig Berry"
#> [4] "Alison Brie" "David Burrows" "Anthony Daniels"
#> [7] "Charlie Day" "Amanda Farinos" "Keith Ferguson"
#> [10] "Will Ferrell" "Will Forte" "Dave Franco"
#> [13] "Morgan Freeman" "Todd Hansen" "Jonah Hill"
poster <- lego_movie %>%
html_nodes("#img_primary img") %>%
html_attr("src")
poster
#> [1] "http://ia.media-imdb.com/images/M/MV5BMTg4MDk1ODExN15BMl5BanBnXkFtZTgwNzIyNjg3MDE@._V1_SX214_AL_.jpg"
The most important functions in rvest are:
-
Create an html document from a url, a file on disk or a string containing html with
read_html()
. -
Select parts of a document using css selectors:
html_nodes(doc, "table td")
(or if you've a glutton for punishment, use xpath selectors withhtml_nodes(doc, xpath = "//table//td")
). If you haven't heard of selectorgadget, make sure to readvignette("selectorgadget")
to learn about it. -
Extract components with
html_tag()
(the name of the tag),html_text()
(all text inside the tag),html_attr()
(contents of a single attribute) andhtml_attrs()
(all attributes). -
(You can also use rvest with XML files: parse with
xml()
, then extract components usingxml_node()
,xml_attr()
,xml_attrs()
,xml_text()
andxml_tag()
.) -
Parse tables into data frames with
html_table()
. -
Extract, modify and submit forms with
html_form()
,set_values()
andsubmit_form()
. -
Detect and repair encoding problems with
guess_encoding()
andrepair_encoding()
. -
Navigate around a website as if you're in a browser with
html_session()
,jump_to()
,follow_link()
,back()
,forward()
,submit_form()
and so on. (This is still a work in progress, so I'd love your feedback.)
To see examples of these function in use, check out the demos.
Install the release version from CRAN:
install.packages("rvest")
Or the development version from github
# install.packages("devtools")
install_github("hadley/rvest")
- Python: Robobrowser, beautiful soup.