使用id从div抓取时的na值

Question

我想在www.apptrace.com中抓取应用程序的id，但是当我执行这段代码时，我得到了一个NA值列表

library(rvest)

URL <- read_html("https://www.apptrace.com")
Identifiant=html_nodes(URL, "#playstore_topchart.topcharts.table .cell.linked.app_cell ") %>% html_attr('id')

​

Answer 1

您正在读取的特定节点没有名为id的属性。它们包含一些带有class = "id"的div，并且它们具有id属性。

您可以使用xpath获取节点，如下所示：

html_nodes(URL, xpath = "//div[@class='id']") %>% html_attr("id")
#>  [1] "363590051"                     "479516143"                    
#>  [3] "544007664"                     "586447913"                    
#>  [5] "1330123889"                    "1105855019"                   
#>  [7] "284882215"                     "553834731"                    
#>  [9] "835599320"                     "507874739"                    
#> [11] "333710667"                     "587366035"                    
#> [13] "525818839"                     "1261357853"                   
#> [15] "664575829"                     "com.facebook.orca"            
#> [17] "com.facebook.katana"           "com.zhiliaoapp.musically"     
#> [19] "ch.threema.app"                "com.instagram.android"        
#> [21] "com.whatsapp"                  "com.google.android.play.games"
#> [23] "com.viber.voip"                "video.like"                   
#> [25] "com.tocaboca.tocahairsalon3"   "com.maxmpz.audioplayer.unlock"
#> [27] "us.zoom.videomeetings"         "org.prowl.torque"             
#> [29] "org.telegram.messenger"        "com.picsart.studio"