Hi, Since we can’t access Google Groups here in China, so please forgive me if anyone has asked this question before.
Sincerely Xiaobo Gu ______________________________________________ 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.
