Prof Brian Ripley
ripley at stats.ox.ac.uk
Sat Aug 19 14:30:04 CEST 2006
On Sat, 19 Aug 2006, Marc Schwartz wrote:
> On Sat, 2006-08-19 at 07:58 -0400, Charles Annis, P.E. wrote:
> > Greetings, Amigos:
> > I have been trying without success to convert a character string,
> > > repeated.measures.columns
> >  "3,6,10"
> > into c(3,6,10) for subsequent use.
> > as.numeric(repeated.measures.columns) doesn't work (likely because of the
> > commas)
> >  NA
> > Warning message:
> > NAs introduced by coercion
> > I've tried many things including
> > strsplit(repeated.measures.columns, split = ",")
> > which produces a list with only one element, viz:
> > []
> >  "3" "6" "10"
> > as.numeric() doesn't like that either.
> > Clearly: 1) I cannot be the first person to attempt this, and 2) I've made
> > this WAY harder than it is.
> > Would some kind soul please instruct me (and perhaps subsequent searchers)
> > how to convert the elements of a string into numbers?
> > Thank you.
> One more step:
> > as.numeric(unlist(strsplit(repeated.measures.columns, ",")))
>  3 6 10
> Use unlist() to take the output of strsplit() and convert it to a
> vector, before coercing to numeric.
Or, more simply, use [] as in
eval(parse(text=paste("c(", repeated.measures.columns, ")")))
looks competitive, and is quite a bit more general (e.g. allows spaces,
works with complex numbers), or you can use scan() from an anonymous file
or a textConnection.
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
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