[R] Selecting rows that are the same in separate data frames

bartjoosen bartjoosen at hotmail.com
Tue Dec 9 16:23:53 CET 2008


I'm not sure what you want, but take a look at ?merge and %in%


ppaarrkk wrote:
> 
> I want to compare two matrices or data frames and select or get an index
> for those rows which are the same in both. I have tried the following :
> 
> 
> 
> 
> 
> 
> a = matrix ( 1:10, ncol = 2 )
> a
> 
> b = matrix ( c ( 2,3,4,7,8,9 ), ncol = 2 )
> b
> 
> a[a==b]
> 
> 
> 
> 
> 
> 
> a = as.data.frame ( matrix ( 1:10, ncol = 2 ) )
> a
> 
> b = as.data.frame ( matrix ( c ( 2,3,4,7,8,9 ), ncol = 2 ) )
> b
> 
> a[a==b]
> 
> 
> 
> 
> 
> 
> 
> 
> Any ideas please.
> 
> 
> Thanks.
> 
> 
> Simon Parker
> Imperial College
> 
> 

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