How to have the sum of a column (with computed data) in the first row?

Question

In org-mode is it possible to generate a table, where there is a column which contains a value computed from values in the other columns and which contains the sum of these values?

More specifically, at the moment I have a table with seven columns, where the last two columns contain values computed from values in the other columns using the following formula:

#+TBLFM: $6=$4-$3;t::$7=$4-$3-$2;t

I would like to include the sum of the last column. Is this possible? If yes, how can this be achieved? When I tried to do this I always got zero. Ideally I would like to have the sum somewhere outside of the table or in the last row (even if I add new rows).

Answer 1

You should use cell formulas (prefixed by := instead of =) for your results.

The example below gives the sum of the last column both at the first and the last rows.

|      |      | 8   |
| Col1 | Col2 | Sum |
|------+------+-----|
| 1    | 3    | 4   |
| 2    | 8    | 10  |
| 3    | -9   | -6  |
|------+------+-----|
|      |      | 8   |
#+TBLFM: $3=$1+$2::@1$3=vsum(@I..@II)::@6$3=vsum(@I..@II)

vsum sums a vector of numbers; @I and @II refer to the first and second hlines.

Answer 2

You may use the orgtbl-aggregate package available on http://melpa.org

The sum of Col1 and Col2 is given in the aggregated table below.

#+name: cc
| Col1 | Col2 | Sum8 |
|------+------+------|
|    1 |    3 |    4 |
|    2 |    8 |   10 |
|    3 |   -9 |   -6 |
#+TBLFM: $3=$1+$2

#+BEGIN: aggregate :table "cc" :cols "vsum(Col1+Col2)"
| vsum(Col1+Col2) |
|-----------------|
|               8 |
#+END:

Documentation here: https://github.com/tbanel/orgaggregate