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dcast's subset argument could behave more like base::subset than reshape2::dcast #4325
Description
Being more used to base::subset, I was surprised when the following didn't work:
x = data.table(a = rep(1:5, 3), b = rep(1:3, each = 5), v = rnorm(15))
dcast(x, a ~ b, value.var = 'v', subset = a > 1)
Error in which(eval(subset, data, parent.frame())) :
argument to 'which' is not logical
That's because dcast.data.table is modelled after reshape2::dcast, where the following is expected:
x = data.table(a = rep(1:5, 3), b = rep(1:3, each = 5), v = rnorm(15))
# works
dcast(x, a ~ b, value.var = 'v', subset = .(a > 1))
Am I missing something? Can't we just drop the .()?
We could also support both -- should be easy to peel off .() if we see it.
Reacted by Jan Gorecki, Cole Miller and g3o2
Activity
venom1204 commentedon May 27, 2026
hi @MichaelChirico @joshhwuu
i have analyzed the issue and i plan to update the
dcast.data.tableto allowsubsetargument to behave like standarddata.tableindexing- the plan is tosubsetexpression without immediate evaluation to support bare logical statements.are there any suggestions or if this sounds good i will happy to proceed with the pr.