[R] How to merge two strings

[Prof Brian Ripley]

On Tue, 16 Aug 2005, Barry Rowlingson wrote:

> 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?

That's actually the reason we have the enhanced sprintf that we do 
nowadays: to enable readable (and translatable) error messages to be 
written via gettextf.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595