[datatable-help] Subsetting that behaves right for both data frames and data.tables?

[Chris Neff]

I have a function where I pass a data frame and some variable names to
calculate statistics on. However, I am at a loss as to how to write it
correctly so that both data.frame and data.table work with it. If I have:

DF = data.frame(x=1:10,y=2:11,z=3:12)

DT = data.table(DF)

var.names = c("x","y")


I can do the following things to subset:

DT[,var.names,with=FALSE]
DF[,var.names]


but of course DT[,var.names] won't give me back what I want, and
DF[,var.names,with=FALSE] returns an error because with doesn't exist there.
So how do I do this?

Thanks,
-Chris
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