Let say I have a data table,

```
dt = data.table(matrix(1:50, nrow = 5));
colnames(dt) = letters[1:10];

> dt
   a  b  c  d  e  f  g  h  i  j
1: 1  6 11 16 21 26 31 36 41 46
2: 2  7 12 17 22 27 32 37 42 47
3: 3  8 13 18 23 28 33 38 43 48
4: 4  9 14 19 24 29 34 39 44 49
5: 5 10 15 20 25 30 35 40 45 50

```

I want to select several discontinuous ranges of columns like: `a`, `c:d`, `f:h` and `j`. This can be done easily via **dplyr's** `select()`:

`dt %>% select(a, c:d, f:h, j)`

I am looking for a **`data.table`** way of achieving the same.

Right now, I can either select columns individually in any order: `dt[ , .(a, c)]` or giving just *one* sequence of column names on the form `startcol:endcol`:

`dt[ , c:f]`

However, I can't combine the above two methods to select *several* column ranges in one shot in `.SDcols`, like I did in `dplyr::select`