如何修复 R 中的以下错误消息：“data.frame 参数中的错误意味着行数不同”？

Question

我是非常在 R 中编码的新手，我被分配了一项网络抓取任务。当我尝试创建数据框时（感谢 youtube！），我不断收到上面标题中列出的错误消息。您是否在下面的代码中发现任何明显的错误，或者您有任何解决问题的建议？谢谢！

link = "http://www.hockeycentral.co.uk/nhl/records/alltimegoal.php"
page = read_html(link)
rank = page %>% html_nodes('#example :nth-child(1)') %>% html_text()
player = page %>% html_nodes('.text-left:nth-child(2)') %>% html_text()
teams = page %>% html_nodes('.text-left:nth-child(3)') %>% html_text()
goals = page %>% html_nodes(':nth-child(4)') %>% html_text()
games = page %>% html_nodes(':nth-child(5)') %>% html_text()
assists = page %>% html_nodes(':nth-child(6)') %>% html_text()
points = page %>% html_nodes(':nth-child(7)') %>% html_text()
PPG = page %>% html_nodes(':nth-child(8)') %>% html_text()
SHG = page %>% html_nodes(':nth-child(9)') %>% html_text()

nhlcareer = data.frame(rank, player, teams, goals, games, assists, points, PPG, SHG, stringsAsFactors 
= FALSE)

Answer 1

你可以使用html_table:

library(rvest)

link = "http://www.hockeycentral.co.uk/nhl/records/alltimegoal.php"
page = read_html(link)
table <- page %>% html_table() 
table <- table[[1]]
head(table)

  Rank        Player                                 Team(s) Goals Games Assists Points PPG SHG
1    1 Wayne Gretzky                      EDM, LAK, STL, NYR   894  1487    1963   2857 204  73
2    2   Gordie Howe                               DET, HFD.   801  1767    1049   1850 211  24
3    3  Jaromir Jagr Pit, WSH, NYR, PHI, DAL, BOS, NJD, FLA.   766  1733    1155   1921 217  11
4    4    Brett Hull                 CGY, STL, DAL, DET, PHX   741  1269     650   1391 265  20
5    5 Marcel Dionne                           DET, LAK, NYR   731  1348    1040   1771 234  19
6    6 Phil Esposito                           CHI, BOS, NYR   717  1282     873   1590 246  23

您所做的逐列提取返回不同的列长度，例如：

> length(player)
[1] 201
> length(rank)
[1] 204

由于 R 不知道如何将列放在一起，它会返回一条错误消息。