To reframe the problem ... the issue is not with the function nchar() (or whatever), it's with the input value rz being null. I suggest you build into the loop whatever actions/outputs you want when rz is NULL.
for (i in 1:10){ if (is.null(rz)) { # do something here } else { if (nchar(rz)>6) { # ... } if (nchar(a[i])+nchar(rz))<6) { # ... } if (nchar(rz)+nchar(a[i+1]>6) { # ... } } } Jean On Fri, Mar 11, 2016 at 8:55 AM, Jan Kacaba <jan.kac...@gmail.com> wrote: > Hello, I have following problem in loops. It occurred to me multiple times > bellow is an example. Inside if() I have sometimes function f(x) which may > return integer(0). If I test f(x)>1 and f(x)=integer(0) I get error. Maybe > it can be solved more eloquently without loop or swithces. I don't know. > > Example: > > a=c("ab","abc","abcd","abcde","abcdefghjk") # vector from which new strings > will be constructed > svec=NULL # vector of string > rz=NULL # string > > for (i in 1:10){ > if (nchar(rz)>6){ > svec[i]=rz > rz=NULL > } > > if (nchar(a[i])+nchar(rz))<6){ > rz=paste(rz,a[i]) > } > > if (nchar(rz)+nchar(a[i+1]>6){ > svec[i]=rz > rz=NULL > } > } > > I'm not interested how to treat nchar() function in particular but general > function. One solution which comes to mind is to redefine function for > example nchar() function like this: > > new.nchar=function(x){ > if (length(nchar(rz))==0){z=0} > if (length(nchar(rz))>0){z=nchar(rz)} > return(z) > } > > Is it correct way of doing this or is there a better way without the need > of redefining new function? > <derek> > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.