The following seems to me to be at least a perverse trap, if not an = outright bug:
> is.numeric(unit(1,"npc")) [1] TRUE > is.numeric(1*unit(1,"npc")) [1] FALSE > is.numeric(unit(0,"npc") +unit(1,"npc")) [1] FALSE ...etc. i.e. is.numeric() appears to be TRUE for class "unit" but false for = class ("unit.arithmetic" "unit" ). Seems to me it ought to b the same for = both. Bert Gunter Genentech Nonclinical Biostatistics (FWIW, I think grid graphics is brilliant!) This was R version 2.11.0dev for Windows btw (not that it makes a difference): sessionInfo() R version 2.11.0 Under development (unstable) (2010-02-15 r51142)=20 i386-pc-mingw32=20 locale: [1] LC_COLLATE=3DEnglish_United States.1252=20 [2] LC_CTYPE=3DEnglish_United States.1252 =20 [3] LC_MONETARY=3DEnglish_United States.1252 [4] LC_NUMERIC=3DC =20 [5] LC_TIME=3DEnglish_United States.1252 =20 attached base packages: [1] datasets splines grid tcltk stats graphics = grDevices [8] utils methods base =20 other attached packages: [1] TinnR_1.0.3 R2HTML_1.59-1 Hmisc_3.7-0 survival_2.35-8 [5] svSocket_0.9-48 lattice_0.18-3 MASS_7.3-5 =20 loaded via a namespace (and not attached): [1] cluster_1.12.1 svMisc_0.9-56 =A0 =A0 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel