In R 2.7.2, if argument 'exclude' is not specified and input is already a factor, function 'table' uses the input as is. In R 2.15.2, in the same case, function 'table' always applies function 'factor' to the input. The time spent by 'factor' is not long, but is not negligible.
I suggest to change 'table' so that 'factor' is not called for input that is already a factor when it is known that the resulting levels is as in the input. This is diff against https://svn.r-project.org/R/trunk/src/library/base/R/table.R. 85c85,88 < a <- factor(a, levels = ll[!(ll %in% exclude)], --- > llexcl <- ll %in% exclude > if (any(llexcl) || > (useNA == "no" && any(is.na(ll)))) > factor(a, levels = ll[!llexcl], 86a90,91 > else > a Function 'table' calls function 'addNA' in some cases. I suggest to change 'addNA', too. This is diff against https://svn.r-project.org/R/trunk/src/library/base/R/factor.R. 336d335 < if (ifany & !any(is.na(x))) return(x) 338c337,339 < if (!any(is.na(ll))) ll <- c(ll, NA) --- > hasNAlev <- any(is.na(ll)) > if ((ifany || hasNAlev) && !any(is.na(x))) return(x) > if (!hasNAlev) ll <- c(ll, NA) Instead of calling 'factor', 'addNA' can also change "levels" attribute and accordingly fill missing value in internal code of the factor. ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
