Question

由于某些网页缺少标记，我很难提取价值：结果猫

我已经访问了这个问题here，但我仍然无法抓取数据。

HTML ：

<div class="result ">
    <span class="result-txt">

        <span class="result-name">
            <a href="/some/value/">COMPANY_NAME</a>
            <a class="result-icons" href="/some/value/COMPANY_NAME_/">
                <span title="Info" class="sprite sprite-info">Info</span>
                <span title="Phone" class="sprite sprite-phone">Phone</span>
            </a>
        </span>

        <em>
            <a href="/some/value/">LOCATION</a>
            <span> ADDRESS </span>
        </em>

        <span class="result-cats">
            <a href="/some/value/" title="CAT1">CAT1</a>
            <a href="/some/value/" title="CAT2">CAT2</a>
        </span>

    </span>
</div>

我正在尝试以下代码，但是由于某些网页没有 results-cats 标记，因此它会给我错误。因此，数据帧具有矢量长度不匹配

码

library(rvest)
library(XML)
library(stringi)

df <- data.frame(CompanyName = NULL, CompanyLink = NULL, Address = NULL, cats = NULL)

for(i in 1:100 ){

  print(paste("Page: ", i, sep = ""))

  url <- "url.com"
  page <- read_html(url)

  CompanyNameNode <- html_nodes(page,'.result-name a:nth-child(1)')
  CompanyName <- html_text(CompanyNameNode)
  CompanyLink <- html_attr(CompanyNameNode, 'href')

  Address <- html_text(html_nodes(page,'.result-txt em'))
  Address <- gsub("[\r\n]", "", Address)

  cats <- html_text(html_nodes(page,'.result-cats'))
  cats <- stri_trim(cats)
  cats <- gsub("[\r\n]", ", ", cats)

  df <- rbind(df, data.frame(CompanyName = CompanyName, 
                             CompanyLink = CompanyLink, 
                             Address = Address, 
                             cats = cats))

}

更新：使用以下代码解决问题

pg <- html_nodes(page,'.result-txt')
cats <- NULL

for(j in 1:length(pg)){
  cats[j] <- ifelse(length(html_text(html_nodes(pg[j],'.result-cats')))==0, 
                   NA, 
                   html_text(html_nodes(pg[j],'.result-cats')))
}

cats <- stri_trim(cats)
cats <- gsub("[\r\n]", ", ", cats)

Answer 1

使用以下代码

解决了这个问题

pg <- html_nodes(page,'.result-txt')
cats <- NULL

for(j in 1:length(pg)){
  cats[j] <- ifelse(length(html_text(html_nodes(pg[j],'.result-cats')))==0, 
                   NA, 
                   html_text(html_nodes(pg[j],'.result-cats')))
}

cats <- stri_trim(cats)
cats <- gsub("[\r\n]", ", ", cats)

Rvest：当元素不存在时抓取数据

1 个答案: