Submitted by: Malcolm Cook; Assigned to: Nobody; R-Forge link
I find that the data.table does NOT behave like data.frame in the case of with=FALSE and selecting no columns.
data.frame will retain empty columns whereas data.table will drop them.
viz:
data.frame(x=1:10)
x
1   1
2   2
3   3
4   4
5   5
6   6
7   7
8   8
9   9
10 10
data.frame(x=1:10)[,-1]
data frame with 0 columns and 10 rows
data.table(x=1:10)
x
1:  1
2:  2
3:  3
4:  4
5:  5
6:  6
7:  7
8:  8
9:  9
10: 10
data.table(x=1:10)[,-1,with=FALSE]
Null data.table (0 rows and 0 cols)