Convert a factor column to multiple boolean columns

Question

Given data that looks like:

library(data.table)
DT <- data.table(x=rep(1:5, 2))

I would like to split this data into 5 boolean columns t

Answer 1

library(data.table)
DT <- data.table(x=rep(1:5, 2))

# add column with id
DT[, id := seq.int(nrow(DT))]

# cast long table into wide
DT.wide <- dcast(DT, id ~ x, value.var = "x", fill = 0, fun = function(x) 1)