Comparing two matrices, row by row

ar1 <- array(data=c(1:16),dim=c(4,4))
ar2 <- array(data=c(1,2,3,3,5:16),dim=c(4,4))
z<-ar1==ar2
ar1
[,1] [,2] [,3] [,4]
[1,] 1 5 9 13
[2,] 2 6 10 14
[3,] 3 7 11 15
[4,] 4 8 12 16
ar2
[,1] [,2] [,3] [,4]
[1,] 1 5 9 13
[2,] 2 6 10 14
[3,] 3 7 11 15
[4,] 3 8 12 16
z
[,1] [,2] [,3] [,4]
[1,] TRUE TRUE TRUE TRUE
[2,] TRUE TRUE TRUE TRUE
[3,] TRUE TRUE TRUE TRUE
[4,] FALSE TRUE TRUE TRUE
which(z==FALSE)
[1] 4

Or

apply(ar1==ar2,1,all)

How to join two arrays using their column names intersection

ar1 <- array(data = c(1:16), dim = c(4,4))
ar2 <- array(data = c(1:16), dim = c(4,4))
colnames(ar1) <- c("A","B","D","E")
colnames(ar2) <- c("C","A","E","B")
# get the common names between the matrices
same <- intersect(colnames(ar1), colnames(ar2))
# join them together
rbind(ar1[,same], ar2[,same])