I think this is a bug. DT.2 <- DT.1 doesn't seem to make a copy in all cases.
> DT.1 <- data.table(x=1, y=1)
> DT.2 <- DT.1
>
> # Both DT.1 and DT.2 are changed.
> DT.2[, y := NULL]
x
[1,] 1
> DT.1
x
[1,] 1
> DT.2
x
[1,] 1
>
> # Only DT.2 is changed
> DT.2[, y := x]
x y
[1,] 1 1
> DT.1
x
[1,] 1
> DT.2
x y
[1,] 1 1
_______________________________________________ datatable-help mailing list [email protected] https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
