I know we can select columns with a character vector in data.table with "..":
col = c("X1", "X2", "X3")
dt[, ..col]
However, it only works when we only use one character vector to select variables. What if I have multiple character vectors and wish to use all of them to select variables from data.table? Can I do it without merging the two vectors?
IV = c("X1", "X2", "X3")
DV = c("Y1", "Y2", "Y3")
dt[, ..(IV+DV)] gives an error "function .. doesn’t exist"
>Solution :
Use c(.).
library(data.table)
MT <- as.data.table(mtcars)
var1 <- c("cyl", "disp")
var2 <- c("gear")
MT[,c(..var1, ..var2)][1:3,]
# cyl disp gear
# <num> <num> <num>
# 1: 6 160 4
# 2: 6 160 4
# 3: 4 108 4