Duncan Murdoch wrote: > On 4/26/2007 9:53 AM, [EMAIL PROTECTED] wrote: >> Hi! >> >> I'm puzzled by the return value of ifelse >> >> consider >> >> x<-integer(0) >> ifelse(is(x, "character"), paste(x), x) >> [1] NA > > The test evaluates to a length 1 logical vector containing FALSE. So > ifelse() tries to return the first entry of x. But x[1] doesn't exist, > so it evaluates to NA, and that's what ifelse() returns.
Thank you for the explanation! Regards, Matthias >> >> whereas >> if (is(x, "character")) return(paste(x)) else x >> [1] integer(0) > > This is quite different. It says to return the expression in the else > clause, which is x. >> >> or >> x<-integer(1) >> ifelse(is(x, "character"), paste(x), x) >> [1] 0 >> >> work as I had anticipated. Is this correct behaviour? > > Yes, this is correct. > > Duncan Murdoch > -- Matthias Burger Project Manager/ Biostatistician Epigenomics AG Kleine Praesidentenstr. 1 10178 Berlin, Germany phone:+49-30-24345-371 fax:+49-30-24345-555 http://www.epigenomics.com [EMAIL PROTECTED] -- Epigenomics AG Berlin Amtsgericht Charlottenburg HRB 75861 Vorstand: Geert Nygaard (CEO/Vorsitzender), Dr. Kurt Berlin (CSO) Oliver Schacht PhD (CFO), Christian Piepenbrock (COO) Aufsichtsrat: Prof. Dr. Dr. hc. Rolf Krebs (Chairman/Vorsitzender) ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
