rvest 表抓取，包括链接

Question

我想从 Wikipedia 上抓取一些表格数据。一些表格列包含指向我想保留的其他文章的链接。我试过this approach，它没有保留 URL。查看 html_table() 函数描述，我没有找到任何包含这些选项的选项。是否有其他软件包或方法可以做到这一点？

library("rvest")

url <- "http://en.wikipedia.org/wiki/List_of_The_Simpsons_episodes"

simp <- url %>%
        html() %>%
        html_nodes(xpath='//*[@id="mw-content-text"]/table[3]') %>%
        html_table()

simp <- simp[[1]]

Answer 1

试试这个

library(XML)
library(httr)
url <- "http://en.wikipedia.org/wiki/List_of_The_Simpsons_episodes"
doc <- content(GET(url))
getHrefs <- function(node, encoding) {  
  x <- xmlChildren(node)$a 
  if (!is.null(x)) paste0("http://", parseURI(url)$server, xmlGetAttr(x, "href"), " | ", xmlValue(x) ) else xmlValue(xmlChildren(node)$text) 
}
tab <- readHTMLTable(doc, which = 3, elFun = getHrefs)
head(tab[, 1:4])
# No. in\nseries No. in\nseason                                                                                              Title                                                               Directed by
# 1              1              1 http://en.wikipedia.org/wiki/Simpsons_Roasting_on_an_Open_Fire | Simpsons Roasting on an Open Fire http://en.wikipedia.org/wiki/David_Silverman_(animator) | David Silverman
# 2              2              2                                     http://en.wikipedia.org/wiki/Bart_the_Genius | Bart the Genius                                                           David Silverman
# 3              3              3                    http://en.wikipedia.org/wiki/Homer%27s_Odyssey_(The_Simpsons) | Homer's Odyssey                      http://en.wikipedia.org/wiki/Wes_Archer | Wes Archer
# 4              4              4       http://en.wikipedia.org/wiki/There%27s_No_Disgrace_Like_Home | There's No Disgrace Like Home                    http://en.wikipedia.org/wiki/Gregg_Vanzo | Gregg Vanzo
# 5              5              5                                   http://en.wikipedia.org/wiki/Bart_the_General | Bart the General                                                           David Silverman
# 6              6              6                                           http://en.wikipedia.org/wiki/Moaning_Lisa | Moaning Lisa                                                                Wes Archer

URL 被保留并由文本中的竖线 (|) 分隔。因此，您可以使用strsplit(as.character(tab[, 3]), split = " | ", fixed = TRUE) 将其拆分。