> What are the values of > > length((Ht_cm[type=='SD'][from_treeline=='above'])[1])
I suspect the error is in the subsetting - the following seems more plausible: Ht_cm[type=='SD' && from_treeline=='above'] Hadley -- http://had.co.nz/ ______________________________________________ R-help@r-project.org mailing list 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.
