Multiple functions on multiple columns by group, and create informative column names

Question

How to adjust a data table manipulation so that, besides sum per category of several colums, it would also calculate other functions at the same time such as <

Answer 1

Here's a data.table answer:

funs_list <- lapply(FunChoice, as.symbol)
dcast(dt, category~1, fun=eval(funs_list), value.var = Colchoice)

It's super fast and does what you want.