用R爬取奥克兰大学的R语言教程

请帮忙看看, 只能抓到第一个pdf, 显示如下:
Warning messages:
1: In if (grepl("^https?://", url)) { :
  the condition has length > 1 and only the first element will be used
2: In if (grepl("^https?://", url)) { :
  the condition has length > 1 and only the first element will be used
3: In if (grepl("^https?://", url)) { :
  the condition has length > 1 and only the first element will be used
我也是这样

沁舞怜 发表于 2019-5-19 00:26
请帮忙看看, 只能抓到第一个pdf, 显示如下:
Warning messages:
1: In if (grepl("^https?://", url)) { ...

download(link,paste("E:/R/",numb,sep = ""), mode = "wb")
把download行代码加两个i就好了

给一个简略版，请参考

1. library(rvest)
   
2. obj <- (read_html('https://www.stat.auckland.ac.nz/~ihaka/120/Lectures/')%>%
   
3.           html_nodes('td:nth-child(2) > a')%>%
   
4.           html_attr('href'))[-1]
   
5. dir.create('C:\\z\\R_lectures')
   
6. setwd('c:/z/R_lectures/')
   
7. lapply(obj, function(x) paste0(url,x)%>%
   
8.          download.file(destfile=x, mode = "wb"))

复制代码

lyfyb99 发表于 2019-5-14 10:48
请帮忙看看, 只能抓到第一个pdf, 显示如下:
Warning messages:
1: In if (grepl("^https?://", url)) { : ...

可以看一下10楼的回复

wind2599 发表于 2019-5-19 00:20
download(link,paste("E:/R/",numb,sep = ""), mode = "wb")
应该是这样吧？

可以了，多谢指教！