使用rvest从可折叠内容的网站中提取信息

Question

网站https://www.moe.gov.sg/schoolfinder/schooldetail?schoolname=ZHONGHUA-SECONDARY-SCHOOL

我只想在DSA talent areas offered in 2021下提取信息

但是，当我使用选择器小工具时，获取路径.is--open:nth-child(4) .moe-collapsible__content

dsa <- html_node(listpage,".is--open:nth-child(4) .moe-collapsible__content") %>% html_text() %>% unlist()
dsa

输出为NA

是否有任何方法从可折叠内容中获取信息？

Answer 1

一种方法是，

library(rvest)
library(dplyr)
library(stringr)

  'https://www.moe.gov.sg/schoolfinder/schooldetail?schoolname=ZHONGHUA-SECONDARY-SCHOOL' %>% 
  read_html() %>% html_nodes('.moe-collapsible__content') %>% html_nodes('.moe-list') %>% html_text() %>% nth(3) %>% str_split('\n')
[[1]]
 [1] "Leadership and Character (Girls and Boys)\r"                                 
 [2] "                                        Chinese Orchestra (Girls and Boys)\r"
 [3] "                                        Choir (Girls and Boys)\r"            
 [4] "                                        Concert Band (Girls and Boys)\r"     
 [5] "                                        Guzheng Ensemble (Girls and Boys)\r" 
 [6] "                                        Badminton (Girls)\r"                 
 [7] "                                        Basketball (Girls)\r"                
 [8] "                                        Table Tennis (Boys)\r"               
 [9] "                                        Volleyball (Boys)\r"   

Answer 2

您可以更精确地使用:contains类来针对正确的父div，然后使用子代选择器移动到子li元素。通过使用部分字符串，您可能可以为2022年提供一些未来的校对。

library(magrittr)
library(rvest)

read_html("https://www.moe.gov.sg/schoolfinder/schooldetail?schoolname=ZHONGHUA-SECONDARY-SCHOOL") %>%
  html_elements('.moe-collapsible:contains("DSA talent areas") li') %>% html_text()