by Joseph Rickert

Quite a few times over the past few years I have highlighted presentations posted by R user groups on their websites and recommended these sites as a source for interesting material, but I have never thought to see what the user groups were doing on GitHub. As you might expect, many people who make presentations at R user group meetings make their code available on GitHub. However as best as I can tell, only a few R user groups are maintaining GitHub sites under the user group name.

The Indy UseR Group is one that seems to be making very good use of their GitHub Site. Here is the link to a very nice tutorial from Shankar Vaidyaraman on using the rvest package to do some web scraping with R. The following code which scrapes the first page from Springer's Use R! series to produce a short list of books comes form Shankar's simple example. 

# load libraries
library(rvest)
library(dplyr)
library(stringr)
 
# link to Use R! titles at Springer site
useRlink = "http://www.springer.com/?SGWID=0-102-24-0-0&series=Use+R&sortOrder=relevance&searchType=ADVANCED_CDA&searchScope=editions&queryText=Use+R"
 
# Read the page
userPg = useRlink %>% read_html()
 
## Get info of books displayed on the page
booktitles = userPg %>% html_nodes(".productGraphic img") %>% html_attr("alt")
bookyr = userPg %>% html_nodes(xpath = "//span[contains(@class,'renditionDescription')]") %>% html_text()
bookauth = userPg %>% html_nodes("span[class = 'displayBlock']") %>% html_text()
bookprice = userPg %>% html_nodes(xpath = "//div[@class = 'bookListPriceContainer']//span[2]") %>% html_text()
pgdf = data.frame(title = booktitles, pubyr = bookyr, auth = bookauth, price = bookprice)
pgdf

 This plot,which shows a list of books ranked by number of downloads, comes from Shankar's extended recommender example.

The Ann Arbor R User Group meetup site has done an exceptional job of creating an aesthetically pleasing and informative web property on their GitHub site.

I am particularly impressed with the way they have integrated news, content and commentary into their “News” section. Scroll down the page and have look at the care taken to describe and document the presentations made to the group. I found the introduction and slides for Bob Carpenter's RStan presentation very well done.

Other RUGs active on GitHub include:

• Cambridge R User Group: meetup site and GitHub site
• Inland Northwest R User Group: GitHub only
• Twin Cities R User Group: meetup site and GitHub site
• UVa R Users Group: meetup site and GitHub site

If your R user group is on GitHub and I have not included you in my short list please let me know about it. I think RUG GitHub sites have the potential for creating a rich code sharing experience among user groups. If you would like some help getting started with GItHub have a look at tutorials on the Murdoch University R User Group webpage.