On Tue, 07 Oct 2003 14:37:26 +0200, Uwe Ligges <[EMAIL PROTECTED]> wrote :
>2. Use "is.na(x) <- TRUE" instead of "x <- NA": > is.na(temp[temp[ ,"t1"] == -999.00, "t1"]) <- TRUE I hadn't heard this advice before. The online help ?is.na gives this cryptic advice: Function 'is.na<-' may provide a safer way to set missingness. It behaves differently for factors, for example. I assume it means "safer than assigning NA", and "differently than assigning NA", but how exactly is it safer, and how is it different? Duncan ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help