## Form a combined factor to split
data(Oats.dat)
tmp <- within(Oats.dat, Trts <- fac.combine(list(Variety, Nitrogen), combine.levels = TRUE))
##Variety levels sorted into alphabetical order
trts.dat <- fac.split(combined.factor = tmp$Trts,
factor.names = list(Variety = NULL, Nitrogen = NULL))
##Variety levels order from Oats.dat retained
trts.dat <- fac.split(combined.factor = tmp$Trts,
factor.names = list(Variety = levels(tmp$Variety), Nitrogen = NULL))
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