See ?duplicated
On Tue, Jul 13, 2010 at 7:42 PM, david hilton shanabrook <
davidshanabr...@me.com> wrote:
> I wrote something to check for duplicate rows in a data frame, but it is
> too inefficient. Is there a way to do this without the nested loops?
>
> This code correctly indicates rows 1-7, 1-8, 2-9 and 7-8 are duplicates.
>
> > m <- matrix(c(1,1,1,1,1, 2,2,2,2,2, 6,6,6,6,6, 3,3,3,3,3, 4,4,4,4,4,
> 5,5,5,5,5, 1,1,1,1,1, 1,1,1,1,1, 2,2,2,2,2, 7,7,7,7,7), ncol=5, byrow=TRUE)
> > df <- data.frame(m)
> > df
> X1 X2 X3 X4 X5
> 1 1 1 1 1 1
> 2 2 2 2 2 2
> 3 6 6 6 6 6
> 4 3 3 3 3 3
> 5 4 4 4 4 4
> 6 5 5 5 5 5
> 7 1 1 1 1 1
> 8 1 1 1 1 1
> 9 2 2 2 2 2
> 10 7 7 7 7 7
> >
> > compareTwoRows <- function(row1, row2){
> + numCol <- 5
> + logicalRow <- row1==row2
> + duplicate <- sum(logicalRow)==numCol
> + return(as.numeric(duplicate))}
> >
> > same <- matrix(0, byrow=TRUE, ncol=10,nrow=10)
> >
> > for (j in 1:9)
> + for (k in (j+1):10)
> + same[j,k] <- compareTwoRows(df[j,],df[k,])
> >
> > same
> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
> [1,] 0 0 0 0 0 0 1 1 0 0
> [2,] 0 0 0 0 0 0 0 0 1 0
> [3,] 0 0 0 0 0 0 0 0 0 0
> [4,] 0 0 0 0 0 0 0 0 0 0
> [5,] 0 0 0 0 0 0 0 0 0 0
> [6,] 0 0 0 0 0 0 0 0 0 0
> [7,] 0 0 0 0 0 0 0 1 0 0
> [8,] 0 0 0 0 0 0 0 0 0 0
> [9,] 0 0 0 0 0 0 0 0 0 0
> [10,] 0 0 0 0 0 0 0 0 0 0
> [[alternative HTML version deleted]]
>
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>
--
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O
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