The following code should suffice to document the problem. Things work properly in the following:
x <- unit.c(unit(5,"mm"),unit(3,"npc")) x
[1] 5mm 3npc
rep(x,2)
[1] 5mm 3npc 5mm 3npc
rep(x, e=2)
[1] 5mm 5npc 3mm 3npc
rep(x,c(2,2))
[1] 5mm 5npc 3mm 3npc However, not so for:
x <- x - unit(1,"mm") x
[1] 5mm-1mm 3npc-1mm
rep(x,2)
[1] 5mm-1mm 3npc-1mm 5mm-1mm 3npc-1mm
rep(x, e=2)
[1] 5mm-1mm 3npc-1mm ##ERROR
rep(x,c(2,2))
Error in rep(unclass(x), ...) : invalid 'times' argument
sessionInfo()
R version 2.10.0 (2009-10-26) i386-pc-mingw32 locale: [1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United States.1252 [3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C [5] LC_TIME=English_United States.1252 attached base packages: [1] datasets splines grid tcltk stats graphics grDevices utils methods base other attached packages: [1] TinnR_1.0.3 R2HTML_1.59-1 Hmisc_3.7-0 survival_2.35-7 svSocket_0.9-48 lattice_0.17-26 MASS_7.3-3 loaded via a namespace (and not attached): [1] cluster_1.12.1 svMisc_0.9-56 tools_2.10.0 Best regards and Happy New Year to All, Bert Gunter Genentech Nonclinical Biostatistics