如何使用R中的readHTMLTable读取已注释掉的HTML表

Question

在过去,我已经能够在R中使用readHTMLTable来提取一些足球统计数据.当今年再次尝试这样做时,表格没有显示,即使它们在网页上可见.以下是一个示例:http://www.pro-football-reference.com/boxscores/201609080den.htm

当我查看页面的源代码时,表格都被注释掉了(我怀疑是为什么readHTMLTable没有找到它们).

示例:在源代码中搜索"team_stats"...

    <!--  
    <div class="table_outer_container">
    <div class="overthrow table_container" id="div_team_stats">
    <table class="stats_table" id="team_stats" data-cols-to-  freeze=1><caption>Team Stats Table</caption>

问题:

如何在源中注释掉表,并在浏览器中显示？

有没有办法使用readHTMLTable(或其他一些方法)读取注释掉的表？

Answer 1

事实上,如果使用XPath comment()选择器,你可以抓住它:

library(rvest)

url <- 'http://www.pro-football-reference.com/boxscores/201609080den.htm'

url %>% read_html() %>%                   # parse html
    html_nodes('#all_team_stats') %>%     # select node with comment
    html_nodes(xpath = 'comment()') %>%   # select comments within node
    html_text() %>%                       # return contents as text
    read_html() %>%                       # parse text as html
    html_node('table') %>%                # select table node
    html_table()                          # parse table and return data.frame

##                                 CAR           DEN
## 1         First Downs            21            21
## 2        Rush-Yds-TDs      32-157-1      29-148-2
## 3   Cmp-Att-Yd-TD-INT 18-33-194-1-1 18-26-178-1-2
## 4        Sacked-Yards          3-18          2-19
## 5      Net Pass Yards           176           159
## 6         Total Yards           333           307
## 7        Fumbles-Lost           0-0           1-1
## 8           Turnovers             1             3
## 9     Penalties-Yards          8-85          4-22
## 10   Third Down Conv.          9-15          5-10
## 11  Fourth Down Conv.           0-0           1-1
## 12 Time of Possession         32:19         27:41