Sum columns duration/days and duration/hours

Question

In my org file I have the table:

|   | Start date             | End date               | State | Task     | Duration/days | Duration (hours) |
|---+------------------------+------------------------+-------+----------+---------------+------------------|
| # | <2018-01-02 Wed 10:30> | <2018-01-02 Wed 12:00> | Taken | some url |        0.0625 |         01:30:00 |
| # | <2018-01-02 Wed 14:00> | <2018-01-02 Wed 18:00> | Taken | some url |      0.166667 |         04:00:00 |
| # | <2018-01-03 Tue 10:30> | <2018-01-03 Wed 12:00> | Taken | some url |        0.0625 |         01:30:00 |
| # | <2018-01-03 Thu 13:30> | <2018-01-03 Thu 18:00> | Taken | some url |        0.1875 |         04:30:00 |
|---+------------------------+------------------------+-------+----------+---------------+------------------|
|   |                        |                        |       |          |               |                  |

#+TBLFM: $6=date(<$3>)-date(<$2>)::$7=60*60*24*$6;T

I have a formula to calculate duration. Nice.

But also I need formulas for total sums in columns Duration/days and Duration/hours

So result must be like this:

|   | Start date             | End date               | State | Task     | Duration/days | Duration (hours) |
|---+------------------------+------------------------+-------+----------+---------------+------------------|
| # | <2018-01-02 Wed 10:30> | <2018-01-02 Wed 12:00> | Taken | some url |        0.0625 |         01:30:00 |
| # | <2018-01-02 Wed 14:00> | <2018-01-02 Wed 18:00> | Taken | some url |      0.166667 |         04:00:00 |
| # | <2018-01-03 Tue 10:30> | <2018-01-03 Wed 12:00> | Taken | some url |        0.0625 |         01:30:00 |
| # | <2018-01-03 Thu 13:30> | <2018-01-03 Thu 18:00> | Taken | some url |        0.1875 |         04:30:00 |
|---+------------------------+------------------------+-------+----------+---------------+------------------|
|   |                        |                        |       |          |      0.479167 |         11:30:00 |

Answer 1

The following formulas work:

#+TBLFM: $6=date(<$3>)-date(<$2>)::$7=60*60*24*$6;T :: @>$6 = vsum(@I..@II) :: @>$7 = vsum(@I..@II);T

vsum is a calc function that adds the components of a 'vector' (here the contents of a column between the first and second hline separators). The last column needs a T format to tell calc that these are HMS values. @>$6 is org mode notation for the last row of column 6. See the References section in the org mode manual for more examples.