R: Extract words from a website - r

Question

I am attempting to extract all words that start with a particular phrase from a website. The website I am using is:
http://docs.ggplot2.org/current/
I want to extract all the words that start with "stat_". I should get 21 names like "stat_identity" in return. I have the following code:
stats <- readLines("http://docs.ggplot2.org/current/")
head(stats)
grep("stat_{1[a-z]", stats, value=TRUE)
I am returned every line containing the phrase "stat_". I just want to extract the "stat_" words. So I tried something else:
gsub("\b^stat_[a-z]+ ", "", stats)
I think the output I got was an empty string, " ", where a "stat_" phrase would be? So now I'm trying to think of ways to extract all the text and set everything that is not a "stat_" phrase to empty strings. Does anyone have any ideas on how to get my desired output?

Answer 1

rvest & stringr to the rescue:
library(xml2)
library(rvest)
library(stringr)
pg <- read_html("http://docs.ggplot2.org/current/")
unique(str_match_all(html_text(html_nodes(pg, "body")),
"(stat_[[:alnum:]_]+)")[[1]][,2])
## [1] "stat_bin" "stat_bin2dCount"
## [3] "stat_bindot" "stat_binhexBin"
## [5] "stat_boxplot" "stat_contour"
## [7] "stat_density" "stat_density2d"
## [9] "stat_ecdf" "stat_functionSuperimpose"
## [11] "stat_identity" "stat_qqCalculation"
## [13] "stat_quantile" "stat_smooth"
## [15] "stat_spokeConvert" "stat_sum"
## [17] "stat_summarySummarise" "stat_summary_hexApply"
## [19] "stat_summary2dApply" "stat_uniqueRemove"
## [21] "stat_ydensity" "stat_defaults"
Unless you need the links (then you can use other rvest functions), this removes all the markup for you and just gives you the text of the website.