在问答论坛中抓取日期

Question

在此线程中

https://www.healthboards.com/boards/aspergers-syndrome/949512-im-lost.html

我正在尝试查找每个 post

的日期

我能找到这个

css="td.thead:first-child"

所以当我运行这个

html_text(html_nodes(read_html("https://www.healthboards.com/boards/aspergers-syndrome/949512-im-lost.html"), css="td.thead:first-child"))

我得到日期

[1] "  \r\n\t\t\t05-13-2013, 11:06 AM\r\n\t\t\t\r\n\t\t\t " "Sponsors "                                    "  \r\n\t\t\t07-26-2013, 08:15 AM\r\n\t\t\t\r\n\t\t\t "
 [4] "  \r\n\t\t\t04-26-2014, 06:28 PM\r\n\t\t\t\r\n\t\t\t " "  \r\n\t\t\t05-07-2014, 02:43 AM\r\n\t\t\t\r\n\t\t\t " "  \r\n\t\t\t09-19-2014, 07:28 AM\r\n\t\t\t\r\n\t\t\t "
 [7] "  \r\n\t\t\t09-19-2014, 07:29 AM\r\n\t\t\t\r\n\t\t\t " "Thread Tools"                                 " \r\n\t\tPosting Rules\r\n\t"                   
[10] "LinkBack"                                     "Bookmark & Share"

我得到了日期，还有 "Thread tools"、"Posting Rules" 和 "Bookmark & Share"..我做错了什么？

Answer 1

您用来匹配日期的 CSS 样式似乎也可以在页面的其他地方找到，从而返回那些其他条目。您可以使用 CSS Selector 只查看 ID 以 'post' 开头的表。选择器是 table[id^='post']，完整的解决方案是：

html_text(html_nodes(read_html("https://www.healthboards.com/boards/aspergers-syndrome/949512-im-lost.html"), css="table[id^='post'] td.thead:first-child"))

[1] "  \r\n\t\t\t05-13-2013, 11:06 AM\r\n\t\t\t\r\n\t\t\t " "  \r\n\t\t\t07-26-2013, 08:15 AM\r\n\t\t\t\r\n\t\t\t "
[3] "  \r\n\t\t\t04-26-2014, 06:28 PM\r\n\t\t\t\r\n\t\t\t " "  \r\n\t\t\t05-07-2014, 02:43 AM\r\n\t\t\t\r\n\t\t\t "
[5] "  \r\n\t\t\t09-19-2014, 07:28 AM\r\n\t\t\t\r\n\t\t\t " "  \r\n\t\t\t09-19-2014, 07:29 AM\r\n\t\t\t\r\n\t\t\t "

在问答论坛中抓取日期

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