[R] How to merge two strings

[Barry Rowlingson]

Claus Hindsgaul wrote:
> Thank you all!
> Paste() was just the function I needed to know!

  Or sprintf:

  > s1 <- "R-"
  > s2 <- "project"
  > sprintf("%s%s",s1,s2)
  [1] "R-project"

  It seems to be much faster:

  > unix.time(for(i in 1:100000){junk=sprintf("%s%s",s1,s2)})
  [1] 1.12 0.00 1.12 0.00 0.00
  > unix.time(for(i in 1:100000){junk=paste(s1,s2,sep='')})
  [1] 5.90 0.01 5.92 0.00 0.00

  Not that I imagine string concatenation will ever be a bottleneck 
worth optimising but there it is. A well-constructed sprintf() call may 
be more readable than a pastey mess though, with all its fiddly commas 
and quotes - contrived example:

  > sprintf("%s://%s%s/%s",scheme,host,dir,file)
  [1] "http://www.foo.com/foo/bar/baz.txt"

  > paste(scheme,'://',host,dir,'/',file,sep='')
  [1] "http://www.foo.com/foo/bar/baz.txt"

  which do you prefer?

Barry