[R] Unique Values of a Matrix

[Todd DeWees]

I found that using 

Sort(unique(c(X)) also works to remove NA....  if you don't mind the unique values being sorted....

Todd DeWees, PhD
Statistician
University of Dundee
Mackenzie Building
Kirsty Semple Way
Dundee DD2 4BF
Scotland UK
PH: 01382-420119


-----Original Message-----
From: David Winsemius [mailto:dwinsemius at comcast.net] 
Sent: 26 February 2010 1:49 PM
To: Henrique Dallazuanna
Cc: Todd DeWees; r-help at r-project.org
Subject: Re: [R] Unique Values of a Matrix


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