One of the easiest things we can do is count the members of the R Foundation—the organization coordinating the development of the core R program. As the ordinary members of the Foundation include only the R Development Core Team, we had better check the supporting members. Anyone can become a supporting member of the Foundation by paying a nominal yearly fee— I highly suggest you do this, by the way. The list is available on the http://r-project.org site, and we will use the XML package (for more detail, see Chapter 2, Getting Data from the Web) to parse the HTML page:

> library(XML)
> page <- htmlParse('http://r-project.org/foundation/donors.html')

Now that we have the HTML page loaded into R, we can use the XML Path Language to extract the list of the supporting members of the Foundation, by reading the list after the Supporting members header:

> list <- unlist(xpathApply(page,
+     "//h3[@id='supporting-members']/following-sibling::ul[1]/li", 
+  ...