See para 10.3.2 'Identifiers' in the R language definition (always distributed with R in the html help system), or ?make.names, for a concise statement of what constitutes a valid variable name in R.
It's actually underscores that might give trouble with older versions, not '.'. But they'd have to be a lot older by R standards (pre 1.9.0). I am not sure why there has been a recent shift away from periods and towards camelCase in some R packages; personally I find a period or underscore much more useful for making a variable name readable. And a mix of camelCase and period.breaks makes it a lot harder to guess which case-sensitive string to use. The number of different combinations of case and period I end up trying for R.Version (occasionally used, never quite often enought to be automatic) defies belief ;-). S Ellison > From: r-help-boun...@r-project.org On Behalf Of Smart Guy > Sent: 04 October 2011 05:20 > To: r-help@r-project.org > Subject: [R] The use of period in function names and variable names > > Hi, > I am looking for some guidance on whether I can use the > period(.) in function names and variable names. ******************************************************************* This email and any attachments are confidential. Any use...{{dropped:8}} ______________________________________________ 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.