stack() seems to drop empty levels. Perhaps there could be a drop=FALSE argument if one wanted all the original levels. In the example below, we may wish to retain level "b" in s$ind even though component LL$b has length 0.
> LL <- list(a = 1:3, b = list()) > s <- stack(LL) > str(s) 'data.frame': 3 obs. of 2 variables: $ values: int 1 2 3 $ ind : Factor w/ 1 level "a": 1 1 1 -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
