On Fri, 20 Aug 2010, Bert Gunter wrote:
Given the string (entered, say, at a readline prompt):
"1 2 -5, 3- 6 4 8 5-7 10" ## only integers will be entered
Presumably only non-negative integers
(Special note to Thomas Lumley: This seems one of the few instances
where eval(parse..)) may actually be appropriate.)
Yes, implementing a new minilanguage is a valid use. It isn't necessary, and
the following could probably be improved on
s<-"1 2 -5, 3- 6 4 8 5-7 10"
npos<-gregexpr("[0-9]+",s)[[1]]
numbers<-as.numeric(substring(s,npos,attr(npos,"match.length")+npos-1))
hyphens<-findInterval(gregexpr("-",s)[[1]],npos)
nn<-as.list(numbers)
nn[hyphens+1]<-mapply(seq,numbers[hyphens]+1,numbers[hyphens+1])
unlist(nn)
-thomas
Thomas Lumley
Professor of Biostatistics
University of Washington, Seattle
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