on 12/10/2008 06:54 PM Viktor Nagy wrote: > Hi, > > My next problem is that I have a data frame with an years column. This > column for some reason is recognised as factor instead of being > numeric. The years go from 1970 to 2007. When I convert it to numeric > with as.numeric then it goes from 1 to 38. Is there a way to convert > it with saving its "levels"? > > This would be actually important as I am affraid of converting my real > values that are recognised as factors as well. > > Thanks, Viktor
Viktor, I would be concerned as to why a column that presumably only contains numeric values is being coerced to a factor to begin with. That would normally only occur when a column contains non-numeric characters. read.table(), for example, uses type.convert() internally to do that and the logic for the type coercion from a character vector is pretty straight-forward. Thus, you may have corrupted year values or at least corrupted characters in that particular column. I would recommend reviewing that data to get a sense of what is going on before proceeding. In general, FAQ 1.10 "How do I convert factors to numeric?" covers the process of converting factors containing numeric characters back to their numeric values: http://cran.r-project.org/doc/FAQ/R-FAQ.html#How-do-I-convert-factors-to-numeric_003f HTH, Marc Schwartz ______________________________________________ [email protected] 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.
