2014-06-01 15:18 GMT+02:00 Michael Brand <michael.ch.brand@gmail.com>:

> Hi Cecil
>
> On Sun, Jun 1, 2014 at 2:24 PM, Cecil Westerhof <cldwesterhof@gmail.com>
> wrote:
> > But what if I would want to know the
> > difference between the previous filled one, divided by the distance?
> >
> > For example:
> > |-------+------------|
> > | value | difference |
> > |-------+------------|
> > |    12 |            |
> > |    15 |          3 |
> > |       |            |
> > |    83 |         34 |
> > |       |            |
> > |       |            |
> > |       |            |
> > |    87 |          1 |
> > |       |            |
> > |       |            |
> > |       |            |
> > |    85 |       -0.5 |
> > |       |            |
> > |-------+------------|
>
> More as a demonstration of what Calc can do, divided up into some
> intermediate steps:
>
> |-------+---------------------------------------------------------|
> | value | difference                                              |
> |-------+---------------------------------------------------------|
> |    12 |                                                         |
> |    15 | [15, 12]                                                |
> |       |                                                         |
> |    83 | [83, nan, 15, 12]                                       |
> |       |                                                         |
> |       |                                                         |
> |       |                                                         |
> |    87 | [87, nan, nan, nan, 83, nan, 15, 12]                    |
> |       |                                                         |
> |       |                                                         |
> |       |                                                         |
> |    85 | [85, nan, nan, nan, 87, nan, nan, nan, 83, nan, 15, 12] |
> |       |                                                         |
> |-------+---------------------------------------------------------|
> #+TBLFM: $2 = if(vlen(@-I$1..@0$1) == 1 || "$1" == "nan", string(""),
> rev(@-I$1..@0$1)); E
>
> |-------+----------------------------------------------------|
> | value | difference                                         |
> |-------+----------------------------------------------------|
> |    12 |                                                    |
> |    15 | [0, 0]                                             |
> |       |                                                    |
> |    83 | [0, nan, 0, 0]                                     |
> |       |                                                    |
> |       |                                                    |
> |       |                                                    |
> |    87 | [0, nan, nan, nan, 0, nan, 0, 0]                   |
> |       |                                                    |
> |       |                                                    |
> |       |                                                    |
> |    85 | [0, nan, nan, nan, 0, nan, nan, nan, 0, nan, 0, 0] |
> |       |                                                    |
> |-------+----------------------------------------------------|
> #+TBLFM: $2 = if(vlen(@-I$1..@0$1) == 1 || "$1" == "nan", string(""),
> 0 * rev(@-I$1..@0$1)); E
>
> Distance to previous element:
>
> |-------+------------|
> | value | difference |
> |-------+------------|
> |    12 |            |
> |    15 |          1 |
> |       |            |
> |    83 |          2 |
> |       |            |
> |       |            |
> |       |            |
> |    87 |          4 |
> |       |            |
> |       |            |
> |       |            |
> |    85 |          4 |
> |       |            |
> |-------+------------|
> #+TBLFM: $2 = if(vlen(@-I$1..@0$1) == 1 || "$1" == "nan", string(""),
> find(0 * rev(@-I$1..@0$1), 0, 2) - 1); E
>
> Previous element:
>
> |-------+------------|
> | value | difference |
> |-------+------------|
> |    12 |            |
> |    15 |         12 |
> |       |            |
> |    83 |         15 |
> |       |            |
> |       |            |
> |       |            |
> |    87 |         83 |
> |       |            |
> |       |            |
> |       |            |
> |    85 |         87 |
> |       |            |
> |-------+------------|
> #+TBLFM: $2 = if(vlen(@-I$1..@0$1) == 1 || "$1" == "nan", string(""),
> subscr(rev(@-I$1..@0$1), find(0 * rev(@-I$1..@0$1), 0, 2)); E
>
> Combined:
>
> |-------+------------|
> | value | difference |
> |-------+------------|
> |    12 |            |
> |    15 |          3 |
> |       |            |
> |    83 |         34 |
> |       |            |
> |       |            |
> |       |            |
> |    87 |          1 |
> |       |            |
> |       |            |
> |       |            |
> |    85 |       -0.5 |
> |       |            |
> |-------+------------|
> #+TBLFM: $2 = if(vlen(@-I$1..@0$1) == 1 || "$1" == "nan", string(""),
> ($1 - subscr(rev(@-I$1..@0$1), find(0 * rev(@-I$1..@0$1), 0, 2))) /
> (find(0 * rev(@-I$1..@0$1), 0, 2) - 1)); E
>
 ​
​Looks very interesting. I have to evaluate this.


> For many here on the list it would probably be easier and more
> interesting to write a TBLFM in Lisp.
>

​I will look into that later. Would it then also be possible to fill
several fields at the same time? At the moment I use the same checks for
several fields. That is not really DRY.

-- 
Cecil Westerhof