Referring to data.table columns by names saved in variables

Question

data.table is a fantastic R package and I am using it in a library I am developing. So far all is going very well, except for one complication. It seems to be m

Answer 1

eval is definitely not a recommended approach to subset a data.table using dynamically saved variables. The following example will help:

# Toy data.table example
DT = data.table(a = c(1,2,3), b = c(4,5,6))

# Saved variable
mVar <- "a"

# Subset
DT[DT[[mVar]] < 2]

eval is very sensitive to complex character expressions and generally not recommended for production code.