[R] Algebraic operation on the missing values

[Petr Pikal]

Hi

see
?complete.cases and/or ?is.na for evaluating non missing entries. 

However in any operation in which you use NA value, result shall be 
NA as you do not know what actually is NA.

HTH
Petr





On 31 Jul 2006 at 11:44, Joanna Procelewska wrote:

Date sent:      	Mon, 31 Jul 2006 11:44:25 +0200 (CEST)
From:           	Joanna Procelewska <jprocelewska at yahoo.com>
To:             	r-help at stat.math.ethz.ch
Subject:        	[R] Algebraic operation on the missing values

> Hi all,
> 
> I have a large set of descriptors, which are stored as the vectors,
> each one containing about 450 elements. Now I have to perform some
> algebraical operations on this set to eliminate the redundant ones.
> The problem is, that not all vales in the vectors are known. Are there
> any norm defined how should I process such vectors? Simple example:
> having two vectors:
> 
> a      b
> 3      4
> 2      null
> 3      6
> 
> I can imagine that a+b is [7 null 9]', but what about scalar product?
> Is it null or have it a value? I don't want to replace missing values
> with the concrete ones, but they significantly complicate my
> computations. 
> 
> Does anyone know whether there are any ways to solve this problem?
> Please share some experience. Really appreciate the help!
> 
> Sincerely,
> 
> Joanna
> 
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Petr Pikal
petr.pikal at precheza.cz