[R] removeing only rows/columns with "na" value from square ( symmetrical ) matrix.

[peter dalgaard]

On May 20, 2012, at 16:37 , Bert Gunter wrote:

> Your problem is not well-defined. In your example below, why not
> remove rows 1,2,6, and 10, all of which contain NA's? Is the matrix
> supposed to be symmetric? Do NA's always occur symmetrically?

...and even if they do, how do you decide whether to remove row/col 9 or row/col 10 in the example? (Or, for that matter, between (1 and 2) and 6. In that case you might chose to remove the smallest no. of row/cols but in "9 vs. 10", the situation is completely symmetric.) 

> 
> You either need to rethink what you want to do or clarify your statement of it.
> 
> -- Bert
> 
> On Sun, May 20, 2012 at 7:17 AM, Nevil Amos <nevil.amos at monash.edu> wrote:
>> I have some square matrices with na values in corresponding rows and
>> columns.
>> 
>> M<-matrix(1:2,10,10)
>> M[6,1:2]<-NA
>> M[10,9]<-NA
>> M<-as.matrix(as.dist(M))
>> print (M)
>> 
>>    1 2 3 4 5 6 7 8 9 10
>> 1   0  2 1 2 1 NA 1 2  1  2
>> 2   2  0 1 2 1 NA 1 2  1  2
>> 3   1  1 0 2 1  2 1 2  1  2
>> 4   2  2 2 0 1  2 1 2  1  2
>> 5   1  1 1 1 0  2 1 2  1  2
>> 6  NA NA 2 2 2  0 1 2  1  2
>> 7   1  1 1 1 1  1 0 2  1  2
>> 8   2  2 2 2 2  2 2 0  1  2
>> 9   1  1 1 1 1  1 1 1  0 NA
>> 10  2  2 2 2 2  2 2 2 NA  0
>> 
>> 
>> How do I remove just the row/column pair( in this trivial example row 6 and
>> 10 and column 6 and 10) containing the NA values?
>> 
>> so that I end up with all rows/ columns that are not NA - e.g.
>> 
>>  1 2 3 4 5 7 8 9
>> 1 0 2 1 2 1 1 2 1
>> 2 2 0 1 2 1 1 2 1
>> 3 1 1 0 2 1 1 2 1
>> 4 2 2 2 0 1 1 2 1
>> 5 1 1 1 1 0 1 2 1
>> 7 1 1 1 1 1 0 2 1
>> 8 2 2 2 2 2 2 0 1
>> 9 1 1 1 1 1 1 1 0
>> 
>> 
>> if i use na omit I lose rows 1,2,6, and 9
>> which is not what I want.
>> 
>> thanks
>> --
>> Nevil Amos
>> Molecular Ecology Research Group
>> Australian Centre for Biodiversity
>> Monash University
>> CLAYTON VIC 3800
>> Australia
>> 
>>        [[alternative HTML version deleted]]
>> 
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> 
> 
> 
> -- 
> 
> Bert Gunter
> Genentech Nonclinical Biostatistics
> 
> Internal Contact Info:
> Phone: 467-7374
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> 
> ______________________________________________
> R-help at r-project.org mailing list
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-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com