NA 尝试循环通过 xpath 节点 R答案

【问题标题】：NA when trying to loop through xpath nodes RNA 尝试循环通过 xpath 节点 R
【发布时间】：2018-03-21 17:22:16
【问题描述】：

我正在尝试从该网站获取数据，其中包含来自里约热内卢的房地产广告：

https://www.zapimoveis.com.br/aluguel/imoveis/rj+rio-de-janeiro/?gclid=EAIaIQobChMIrLjc2u7m2QIVhYGRCh3w9g0GEAAYASAAEgJKdvD_BwE#{%22parametrosautosuggest%22:[{%22Bairro%22:%22%22,%22Zona%22:%22%22,%22Cidade%22:%22RIO%20DE%20JANEIRO%22,%22Agrupamento %22:%22%22,%22Estado%22:%22RJ%22}],%22pagina%22:%221%22,%22ordem%22:%22Relevancia%22,%22paginaOrigem%22:%22ResultadoBusca%22, %22semente%22:%222109841258%22,%22formato%22:%22Lista%22}

当我逐个进入节点时，我的代码工作正常，但是当我尝试循环遍历 xpath 节点时，包“rvest”中的函数 html_text() 返回 N/A。

这是我目前写的一段代码：

library(rvest)
library(httr)



Url<-"https://www.zapimoveis.com.br/aluguel/imoveis/rj+rio-de-janeiro/?gclid=EAIaIQobChMIrLjc2u7m2QIVhYGRCh3w9g0GEAAYASAAEgJKdvD_BwE#{%22parametrosautosuggest%22:[{%22Bairro%22:%22%22,%22Zona%22:%22%22,%22Cidade%22:%22RIO%20DE%20JANEIRO%22,%22Agrupamento%22:%22%22,%22Estado%22:%22RJ%22}],%22pagina%22:%221%22,%22ordem%22:%22Relevancia%22,%22paginaOrigem%22:%22ResultadoBusca%22,%22semente%22:%222109841258%22,%22formato%22:%22Lista%22}"


website<- GET(Url)


#vectors that will store the data I want to collect
condominio<-vector()
Iptu<-vector()


#loop through nodes
for (i in 1:2){
condominio[i]<- website %>%
  read_html() %>%
html_node(xpath = "/html/body/div[3]/div[2]/section/div/article[i]/section[1]/a/div/span") %>%
html_text()

Iptu[i]<- website %>%
  read_html() %>%
  html_node(xpath = "/html/body/div[3]/div[2]/section/div/article[i]/section[1]/a/div/strong") %>%
  html_text()




}

如果我将变量 i 替换为固定数字，例如 2，代码似乎可以正常工作。

谁能帮我找到从更多广告中提取数据的方法？

非常感谢！

【问题讨论】：

标签： r xpath web-scraping rvest httr

【解决方案1】：

我更喜欢指定 css 而不是 xpath。试试这样的。

library(rvest)
library(httr)

Url<-"https://www.zapimoveis.com.br/aluguel/imoveis/rj+rio-de-janeiro/?gclid=EAIaIQobChMIrLjc2u7m2QIVhYGRCh3w9g0GEAAYASAAEgJKdvD_BwE#{%22parametrosautosuggest%22:[{%22Bairro%22:%22%22,%22Zona%22:%22%22,%22Cidade%22:%22RIO%20DE%20JANEIRO%22,%22Agrupamento%22:%22%22,%22Estado%22:%22RJ%22}],%22pagina%22:%221%22,%22ordem%22:%22Relevancia%22,%22paginaOrigem%22:%22ResultadoBusca%22,%22semente%22:%222109841258%22,%22formato%22:%22Lista%22}"

website<- GET(Url)

#vectors that will store the data I want to collect
condominio<-vector()
Iptu<-vector()

condominio<- website %>%
  read_html() %>%
  html_nodes("article section a div span") %>%
  html_text()

Iptu<- website %>%
  read_html() %>%
  html_nodes("article section a div strong") %>%
  html_text()

【讨论】：