# [R] Algebraic operation on the missing values

Joanna Procelewska jprocelewska at yahoo.com
Mon Jul 31 14:37:33 CEST 2006

```Thanks for the answer.

The problem is I have to perform a forward selection on the set and in every
step construct an orthonormal base for the subspace spanned on the selected
vectors. This means that I can use only the "full" vectors for the constructing
a base, or?

Joanna

--- Petr Pikal <petr.pikal at precheza.cz> schrieb:

> 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
>
> > 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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