Re: [R] How to merge two strings

From: Barry Rowlingson <B.Rowlingson_at_lancaster.ac.uk>
Date: Tue 16 Aug 2005 - 21:58:52 EST

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



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