From: Carsten Dominik <carsten.dominik@gmail.com>
To: Carsten Dominik <dominik@uva.nl>
Cc: emacs-orgmode@gnu.org
Subject: Re: Spreadsheet and weighted means
Date: Mon, 29 Sep 2008 10:44:10 +0200 [thread overview]
Message-ID: <28508EE0-1CAF-4624-8304-456670929C8B@gmail.com> (raw)
In-Reply-To: <9136F031-BBCD-4A80-A117-6047C5D3F777@uva.nl>
On Sep 29, 2008, at 10:43 AM, Carsten Dominik wrote:
>
> On Sep 20, 2008, at 9:00 AM, Nicolas Goaziou wrote:
>
>> Hello,
>>
>> I stumbled upon this problem : I'd like to compute the weighted
>> mean of
>> some values, even though cells might be empty. In fact, I'm aiming at
>> something like this :
>>
>> | | Coeff. | 0.2 | 0.5 | 1 |
>> |-----------+--------+--------+--------+--------|
>> | Name | Mean | Test 1 | Test 2 | Test 3 |
>> |-----------+--------+--------+--------+--------|
>> | Student A | 10 | 15 | 12 | 8 |
>> | Student B | 12 | | 16 | 10 |
>>
>> where 10=(15*0.2+12*0.5+8*1)/(0.2+0.5+1) and 12=(16*0.5+10*1)/(0.5+1)
>>
>> I just can't guess what has to be put in @3$2 as a column formula to
>> calculate those mean means… I perhaps have overlooked something
>> simple.
>> Anyway, if anyone has a clue here, I will be pleased to hear it.
>
> Hi Nicolas, there s no builtin way to deal with this, in particular
> with the fact that you want to treat empty fields as non-existing,
> and therefore also to ignore the corresponding weight.
>
> You cou write a Lisp function to do this, though:
>
> (defun my-wmean (values weights)
> (let ((vsum 0) (wsum 0))
> (while (and values weights)
> (setq v (pop values) w (pop weights))
> (unless (equal "" v)
> (setq vsum (+ vsum (* (string-to-number w) (string-to-number v)))
> wsum (+ wsum (string-to-number w)))))
> (/ vsum wsum)))
>
>
> The you could use this as your equation:
>
> | | Coeff. | 0.2 | 0.5 | 1 |
> |-----------+--------+--------+--------+--------|
> | Name | 0 | Test 1 | Test 2 | Test 3 |
> |-----------+--------+--------+--------+--------|
> | Student A | 10 | 15 | 12 | 8 |
> | Student B | 12 | | 16 | 10 |
> #+TBLFM: $2='(wmean '($3..$5) '(@1$3..@1$5));E%d
Typo: the function call must be `my-wmean', not just `wmean'.
- CarstenG
next prev parent reply other threads:[~2008-09-29 8:44 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-20 7:00 Spreadsheet and weighted means Nicolas Goaziou
2008-09-29 8:43 ` Carsten Dominik
2008-09-29 8:44 ` Carsten Dominik [this message]
2008-10-01 16:46 ` Nicolas Goaziou
2008-10-01 19:26 ` Carsten Dominik
2008-10-01 19:45 ` Embedded elisp formulas, was: " Eric Schulte
2008-10-01 20:29 ` Paul R
2008-10-02 0:03 ` Eric Schulte
2008-10-02 11:44 ` Carsten Dominik
2008-10-08 23:12 ` ANN: org-eval-light.el was: " Eric Schulte
2008-11-06 1:19 ` Eric Schulte
2008-11-09 7:02 ` Carsten Dominik
2008-11-10 19:51 ` Daniel Clemente
2008-10-04 8:49 ` Nicolas Goaziou
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