Thursday, August 25, 2011

String functions in R

Here's a quick cheat-sheet on string manipulation functions in R, mostly cribbed from Quick-R's list of String Functions with a few additional links.

  • substr(x, start=n1, stop=n2)
  • grep(pattern,x, value=FALSE, ignore.case=FALSE, fixed=FALSE)
  • gsub(pattern, replacement, x, ignore.case=FALSE, fixed=FALSE)
  • gregexpr(pattern, text, ignore.case=FALSE, perl=FALSE, fixed=FALSE)
  • strsplit(x, split)
  • paste(..., sep="", collapse=NULL)
  • sprintf(fmt, ...)
  • toupper/tolower(x)
  • nchar(x)

Also see Regular Expressions as used in R and R String processing.

Note: Just to be clear, R is far from an ideal platform for processing text. For anything where that's the major concern, you're better off going to Python or Ruby.