[R] Comparing rows of matrices with different dimensions

[Berton Gunter]

If I understand you correctly, 

## not tested

apply(cbind(a[,-3],b),1,function(x)isTRUE(all.equal(x[1:2],x[3:4])))

or something similar. The basic idea is just to drop the last column of a
and check to see whether rows are the same (possible within numeric fuzz).
This assumes order counts. If the rows must just contain the same values
(possibly replicated different numbers of times, then add calls to unique
(or maybe use setdiff if numeric fuzz is not an issue).

HTH

Cheers,
Bert

-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
 
"The business of the statistician is to catalyze the scientific learning
process."  - George E. P. Box
 
 

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Antje Döring
> Sent: Monday, November 21, 2005 7:57 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Comparing rows of matrices with different dimensions
> 
>  
> 
> Hi there,
> 
>  
> 
> I have a question, which I thought is very easy to solve, but 
> somehow I can't find a solution. Probably someone could help 
> me quickly?
> 
>  
> 
> Here it is:
> 
>  
> 
> I have two matrices:
> 
>  
> 
> a
> 
>      [,1] [,2] [,3]
> 
> [1,]    1    4    9
> 
> [2,]    2    6   10
> 
> [3,]    3    6   11
> 
> [4,]    4    8   12
> 
>  
> 
>  
> 
> b
> 
>      [,1] [,2]
> 
> [1,]    1    4
> 
> [2,]    2    5
> 
> [3,]    3    6
> 
>  
> 
> Now I want to find out which rows of b can also be found in a 
> (without its last column). So the solution must be something 
> like either "TRUE FALSE TRUE" or the rows where their is a 
> match (rows 1 and 3)
> 
>  
> 
> Till now I have tried things like b %in% a[,1:2] or so but 
> that doesn't work because I want to compare the WHOLE row of 
> b with the whole row of a without column 3.
> 
>  
> 
> Thank you very much for any help.
> 
>  
> 
> Regards, Antje
> 
> 
> 	[[alternative HTML version deleted]]
> 
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