Off topic:how compare rows together?

Question

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I have data like as below:

I want to compare each row with rows below and then get number of equal value in each 2 rows.

   V1  V2  V3   V4  V5
1   3   2   2   3   3
2   2   2   0   2   3
3   2   3   2   2   0
4   0   3   2   1   3
5   2   2   2   2   3

I wrote the code below, but in output I face with NA.

library(data.table)
data=as.data.frame(read.table("data.csv",header=TRUE))

findMatch <- function(i,n){
  tmp <- colSums(t(data[-(1:i),]) == unlist(data[i,]))
  tmp <- tmp[tmp > n]
  if(length(tmp) > 0)return(data.table(sample=rownames(data[i],duplicate=names(tmp),match=tmp))
  return(NULL)
}
tab <- rbindlist(lapply(1:(nrow(data)-1),findMatch,n=0))
tab

Output:

       sample duplicate match
 1:      1        NA    NA
 2:      1        NA    NA
 3:      1        NA    NA
 4:      1        NA    NA

I expect this out put:

       sample duplicate match
 1:      1        2    2
 2:      1        3    1
 3:      1        4    2
 4:      1        5    3