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Re: [O] table formula help...


From: Thierry Banel
Subject: Re: [O] table formula help...
Date: Mon, 08 Dec 2014 22:57:38 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0

Le 08/12/2014 19:02, Michael Brand a écrit :
>
> Good. My opinion is about to replace it with what.
>
> https://github.com/tbanel/orgaggregate#empty-and-malformed-input-cells
> says:
>
>     An input cell may be empty. In this case, it is silently replaced
>     by zero. In an output cell, if the computed result is zero, it not
>     output, leaving a blank cell. This allows for empty input cells to
>     result in empty output cells.
>
> I understand the intention very well (the proof is in the references
> at the bottom ;-) ). Nevertheless I find the compromise goes too far
> when in the following example the sum and mean for a0 and b0 are
> empty. I would prefer 0 there even when for the time being it is at
> the cost of that c results in a sum and mean of 0 too.

You instantly found the weakness of the current design!

> It would mean to remove the above "In an output cell, if the computed
> result is zero, it not output, leaving a blank cell. [...]".

I'm inclined to agree with you. Dropping the /zero output becomes blank/
feature would be the best short-term compromise.

>  Or - when
> you want to bother with the implementation - to change it into "If all
> input cells of a computation are empty then the result cell is left
> empty.".

Yes, this is the correct specification. Testing that *all* inputs are blank.
Unfortunately, implementing this is a lot of work, because we need to
create new data structures to remember whether input fields are blank.

> #+TBLNAME: original
> | Item | Value |
> |------+-------|
> | a2   |     1 |
> | a2   |     1 |
> | a0   |    -1 |
> | a0   |     1 |
> | b2   |     2 |
> | b2   |       |
> | b0   |     0 |
> | b0   |       |
> | c    |       |
> | c    |       |
>
> #+BEGIN: aggregate :table original :cols "Item sum(Value) mean(Value)"
> | Item | sum(Value) | mean(Value) |
> |------+------------+-------------|
> | a2   |          2 |           1 |
> | a0   |            |             |
> | b2   |          2 |           1 |
> | b0   |            |             |
> | c    |            |             |
> #+END
>
> Could you please add this example or something in the same sense to
> the unittests.org before any other change?

Good idea. I'll do that.

> https://github.com/tbanel/orgaggregate#empty-and-malformed-input-cells
> continues:
>
>     The empty cell handling may be changed in the futur. For instance,
>     we may want to compute an average aggregation ignoring empty cells
>     (right now, empty cells contribute to the average by pulling it
>     toward zero).
>
> As I understand orgaggregate already uses Calc vectors.

Yes.

> Maybe then it
> could use and benefit from org-table-make-reference which has the
> necessary arguments and asks for a Lisp list? See
> testing/lisp/test-org-table.el:
> - The application of the mode string variations for TBLFM are in
>   test-org-table/references/mode-string-*.
> - The same variations for org-table-make-reference are in
>   test-org-table/org-table-make-reference/mode-string-*
>

Definitely interesting. Someone else has already bumped into the empty
cells thing.

> Michael

Thierry




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