转载:R语言rvest包使用
R中有好几个包都可以抓取网页数据，但是rvest + CSS Selector最方便。
通过查看器立刻知道表格数据都在td:nth-child(1),td:nth-child(3)之类的节点中，直接代码提取就行了。
library(rvest)
先看看都有什么
freak <- html_session("http://torrentfreak.com/top-10-most-pirated-movies-of-the-week-130304/")
freak
<session> http://torrentfreak.com/top-10-most-pirated-movies-of-the-week-130304/
Status: 200
Type: text/html; charset=UTF-8
Size: 24983
freak %>% html_nodes("td:nth-child(3)") %>% html_text() %>% .[1:10]
[1] "Silver Linings Playbook "
[2] "The Hobbit: An Unexpected Journey "
[3] "Life of Pi (DVDscr/DVDrip)"
[4] "Argo (DVDscr)"
[5] "Identity Thief "
[6] "Red Dawn "
[7] "Rise Of The Guardians (DVDscr)"
[8] "Django Unchained (DVDscr)"
[9] "Lincoln (DVDscr)"
[10] "Zero Dark Thirty "
freak %>% html_nodes("td:nth-child(1)") %>% html_text() %>% .[2:11]
[1] "1" "2" "3" "4" "5" "6" "7" "8" "9" "10"
freak %>% html_nodes("td:nth-child(4)") %>% html_text() %>% .[1:10]
[1] "7.4 / trailer" "8.2 / trailer" "8.3 / trailer" "8.2 / trailer"
[5] "8.2 / trailer" "5.3 / trailer" "7.5 / trailer" "8.8 / trailer"
[9] "8.2 / trailer" "7.6 / trailer"
freak %>% html_nodes("td:nth-child(4) a[href*='imdb']") %>% html_attr("href") %>% .[1:10]
[1] "http://www.imdb.com/title/tt1045658/"
[2] "http://www.imdb.com/title/tt0903624/"
[3] "http://www.imdb.com/title/tt0454876/"
[4] "http://www.imdb.com/title/tt1024648/"
[5] "http://www.imdb.com/title/tt2024432/"
[6] "http://www.imdb.com/title/tt1234719/"
[7] "http://www.imdb.com/title/tt1446192/"
[8] "http://www.imdb.com/title/tt1853728/"
[9] "http://www.imdb.com/title/tt0443272/"
[10] "http://www.imdb.com/title/tt1790885/?"
#构建数据框
data.frame(movie=freak %>% html_nodes("td:nth-child(3)") %>% html_text() %>% .[1:10],
rank=freak %>% html_nodes("td:nth-child(1)") %>% html_text() %>% .[2:11],
rating=freak %>% html_nodes("td:nth-child(4)") %>% html_text() %>% .[1:10],
imdb.url=freak %>% html_nodes("td:nth child(4) a[href*='imdb']") %>% html_attr("href") %>% .[1:10],stringsAsFactors=FALSE)
movie rank rating imdb.url
1 Silver Linings Playbook 1 7.4 / trailer http://www.imdb.com/title/tt1045658/
2 The Hobbit: An Unexpected Journey 2 8.2 / trailer http://www.imdb.com/title/tt0903624/
3 Life of Pi (DVDscr/DVDrip) 3 8.3 / trailer http://www.imdb.com/title/tt0454876/
4 Argo (DVDscr) 4 8.2 / trailer http://www.imdb.com/title/tt1024648/
5 Identity Thief 5 8.2 / trailer http://www.imdb.com/title/tt2024432/
6 Red Dawn 6 5.3 / trailer http://www.imdb.com/title/tt1234719/
7 Rise Of The Guardians (DVDscr) 7 7.5 / trailer http://www.imdb.com/title/tt1446192/
8 Django Unchained (DVDscr) 8 8.8 / trailer http://www.imdb.com/title/tt1853728/
9 Lincoln (DVDscr) 9 8.2 / trailer http://www.imdb.com/title/tt0443272/
10 Zero Dark Thirty 10 7.6 / trailer http://www.imdb.com/title/tt1790885/?
如果不考虑网址，还有更简单的方式：
freak %>% html_nodes("table") %>% html_table()
[[1]]
Ranking (last week) Movie IMDb Rating / Trailer
1 torrentfreak.com <NA> <NA> <NA>
2 1 (5) Silver Linings Playbook 7.4 / trailer
3 2 (back) The Hobbit: An Unexpected Journey 8.2 / trailer
4 3 (9) Life of Pi (DVDscr/DVDrip) 8.3 / trailer
5 4 (back) Argo (DVDscr) 8.2 / trailer
6 5 (…) Identity Thief 8.2 / trailer
7 6 (1) Red Dawn 5.3 / trailer
8 7 (2) Rise Of The Guardians (DVDscr) 7.5 / trailer
9 8 (4) Django Unchained (DVDscr) 8.8 / trailer
10 9 (6) Lincoln (DVDscr) 8.2 / trailer
11 10 (back) Zero Dark Thirty 7.6 / trailer
