Turn a table into a data frame with html_table()

If a table has a header row (with th elements) and no gaps, scraping it is straightforward, as with the following table (having ID "clean"):

Mountain	Height	First ascent	Country
Mount Everest	8848	1953	Nepal, China
...

Here's the same table (having ID "dirty") without a designated header row and a missing cell in the first row:

Mountain	Height	First ascent	Country
Mount Everest	8848	1953
...

For such cases, html_table() has an extra argument you can use to correctly parse the table, as shown in the video. Missing cells are automatically recognized and replaced with NA values.

Both tables are contained within the mountains_html document.