[R] Extract from matrix

[John Kane]

?which 

Does something like this help?

which(aa==29)
aa[ -which(aa==29)]

--- _Fede_ <r_stat_solutions at hotmail.es> wrote:

> 
> Hi all.
> 
> I have certain problem with the extraction of data
> from matrices. I know how
> extract elements from a matrix, but what I would
> like to do is to extract a
> concrete number, not an element. For example if I
> have this matrix X:
> 
>      [,1] [,2] [,3] [,4]
> [1,]    3   13   23   33
> [2,]    9   19   29   39
> [3,]   10   20   30   40
> 
> I can do X[-2] or X[2] in order to eliminate the
> element of the matrix or to
> extract it, respectively.
> 
> But, what I need is to extract or to eliminate a
> value of the matrix. For
> example the 29.
> 
> Can I do this? How?
> 
> Thanks for the help.
> -- 
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>
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