converting two column data table to data table with colnames from one column and values from the other

Question

Any more elegant way to do tdt as shown in the following example using base or data.table functions and operations only?

library(data.table)
dt <- data.table(a = letters[1:5], b = 1:5)
dt
# a b
# 1: a 1
# 2: b 2
# 3: c 3
# 4: d 4
# 5: e 5
tdt <- data.table(t(matrix(dt$b, dimnames = list(dt$a, NULL))))
tdt
# a b c d e
# 1: 1 2 3 4 5

Answer 1

We can use dcast

dcast(dt[, rn := 1], rn~a, value.var = "b")[, rn := NULL][]
#   a b c d e
#1: 1 2 3 4 5

Or

setDT(setNames(as.list(dt$b), dt$a))[]
#   a b c d e
#1: 1 2 3 4 5

Or

dt[, setNames(as.list(b),a )]