我已经构建了一个函数,该函数可以获取网址并在抓取网页后返回所需的结果。该功能如下所述:
library(httr)
library(curl)
library(rvest)
library(dplyr)
sd_cat <- function(url){
cat <- curl(url, handle = new_handle("useragent" = "myua")) %>%
read_html() %>%
html_nodes("#breadCrumbWrapper") %>%
html_text()
x <- cat[1]
#y <- gsub(pattern = "\n", x=x, replacement = " ")
y <- gsub(pattern = "\t", x=x, replacement = " ")
y <- gsub("\\d|,|\t", x=y, replacement = "")
y <- gsub("^ *|(?<= ) | *$", "", y, perl=T)
z <- gsub("\n*{2,}","",y)
z <- gsub(" {2,}",">",z)
final <- substring(z,2)
final <- substring(final,1,nchar(final)-1)
final
#sample discontinued url: "http://www.snapdeal.com//product/givenchy-xeryus-rouge-g-edt/1978028261"
#sample working url: "http://www.snapdeal.com//product/davidoff-cool-water-game-100ml/1339014133"
}
在包含多个网址的字符向量上使用sapply时,此函数可以正常工作,但是如果中断了单个网址,则该函数将抛出
open.connection(x,“rb”)中的错误:HTTP错误404。
我需要一种方法来跳过不连续的URL,以使该功能正常工作。
最佳答案
更好的解决方案是使用httr并在响应不正确时故意采取措施:
library(httr)
library(rvest)
sd_cat <- function(url){
r <- GET(url, user_agent("myua"))
if (status_code(r) >= 300)
return(NA_character_)
r %>%
read_html() %>%
html_nodes("#breadCrumbWrapper") %>%
.[[1]] %>%
html_nodes("span") %>%
html_text()
}
sd_cat("http://www.snapdeal.com//product/givenchy-xeryus-rouge-g-edt/1978028261")
sd_cat("http://www.snapdeal.com//product/davidoff-cool-water-game-100ml/1339014133")
(我还用更好的rvest替换了您的正则表达式)
关于r - 使用RVest(R)进行网页抓取时,URL停止使用,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/34311626/