From: Rainer M Krug <firstname.lastname@example.org>
To: Thorsten <email@example.com>
Subject: Re: Re: org-table formulas with missing values
Date: Sat, 5 Mar 2011 12:01:16 +0100 [thread overview]
Message-ID: <AANLkTi=NcQ-1oPxjQ14yWju2-P+=iHBTcmC7Ai3SF8AM@mail.gmail.com> (raw)
On Sat, Mar 5, 2011 at 11:55 AM, Thorsten
> Bastien <firstname.lastname@example.org> writes:
>> Hi Thorsten,
>> Thorsten <email@example.com> writes:
>>> Ok, trial and error suggests that missing values in numeric columns can
>>> be represented as 0 in formulas, in string columns as "". Is there
>>> something like NaN in calc/org-table?
>> I don't know what is NaN. Can you give an example of what you're trying
>> to achieve?
> NaN stands for NotaNumber and is usually used in statistic programs to
> denote missing numerical values
NaN ia, as you state, NotANumber, but it is NOT a missing value, for
which the abbreviation is NA (Not Vavailable). An example for NaN
would be 1/0 - the value is there, but it is not a number. And,
consequently, NaN and NA can be treated separately. In general, if you
enter values, you use NA, as you usually do not enter values which are
not a number...
> (that deserve special treatment, since
> including them in the calculations as 0 values would not be wise due to
> introduced bias or confusion with true measurements of a value=0).
> Fot example:
> | day | tel- calls | change (%) |
> | 1 | 7 | 0 |
> | 2 | 2 | -71 |
> | 3 | 3 | 50 |
> | 4 | | 0 |
> | 5 | 2 | round((2/0) 100, 0) |
> | 6 | 0 | 0 |
> | 7 | 3 | round((3/0) 100, 0) |
> #+TBLFM: $3=if(@$-1=0,0,round((((@$-1-@-1$-1) / @-1$-1) * 100),
> Here one measurement (day 4) was missed, one day had 0 tel-calls (day
> The change (%) is :
> ((calls day x) - (calls day x-1)) / (calls day x-1) * 100.
> The column-formula treats measurment and zero value the same, although
> it would be better to replace the missing value with the average (but
> how to adress it in the formula if not with 0 ?), and it treats the zero
> measurement like a missing value here. Even if there would be no zero
> value here, the missing value would cause a 'divide by zero' error.
> I could write 'nan' instead of leaving a blank, and use the string in
> the formula, but this causes errors.
> But calc does know the concept of nan: "The variables `inf', `uinf', and
> `nan' stand for infinite or indeterminate values. It's best not to use
> them as regular variables, since Calc uses special algebraic rules when
> it manipulates them. Calc displays a warning message if you store a
> value into any of these special variables."
> I'm not sure how to use that nan variable in tables and formulas - it
> seems not to be recognized.
NEW GERMAN FAX NUMBER!!!
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
Biology, UCT), Dipl. Phys. (Germany)
Centre of Excellence for Invasion Biology
Natural Sciences Building
Office Suite 2039
Main Campus, Merriman Avenue
Cell: +27 - (0)83 9479 042
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next prev parent reply other threads:[~2011-03-05 11:01 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-26 18:32 org-table formulas with missing values Thorsten
2011-02-27 0:01 ` Thorsten
2011-02-27 11:45 ` Bastien
2011-03-05 10:55 ` Thorsten
2011-03-05 11:01 ` Rainer M Krug [this message]
2011-03-06 22:44 ` Thorsten
2011-03-06 23:03 ` suvayu ali
2011-03-08 19:18 ` Thorsten
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