[R] Unique Values of a Matrix

[David Winsemius]

On Feb 26, 2010, at 8:17 AM, Henrique Dallazuanna wrote:

> Try this:
>
> unique(c(X))

I did but it returned NA as did:    unique(as.vector(X)).

To get rid of the NA's I needed to do:

X[!duplicated(as.vector(X)) & !is.na(X)]

(Logical indexing and does need as.vector() , or c() , to "straighten  
out" the index expression.)

Not sure why applying the straightening to the second logical term is  
not equivalent:
 > X[!duplicated(X) & !is.na(as.vector(X))]
[1] 1 2 4 3 1 7 2

This also:
 > unique(c(X))[!is.na(unique(c(X)))]
[1] 1 2 4 3 7

>
> On Fri, Feb 26, 2010 at 10:06 AM, Todd DeWees
> <T.DeWees at cpse.dundee.ac.uk> wrote:
>> I have a 280,000 x 11 matrix with various values and many NA  
>> values.  What I would like to do is get a vector of every unique  
>> value in the matrix.
>>
>> For example:
>>
>> X =     [ 1    2    NA
>>          4    3      1
>>          7  NA  2 ]
>>
>> Returns:
>> Unique_X = [ 1, 2, 3, 4, 7]
>>
>> Thanks,
>> Todd
>>
>>
>>        [[alternative HTML version deleted]]
>>
>> ______________________________________________
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>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
> -- 
> Henrique Dallazuanna
> Curitiba-Paraná-Brasil
> 25° 25' 40" S 49° 16' 22" O
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
Heritage Laboratories
West Hartford, CT