Thank you very much for the help, that's what I was looking for! Also my apologies for sending an html, I thought I turned it off (hopefully this time works).
Best regards, Nicola ______________________________________________ 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.