How to check if there is a vector in a matrix in R?

Question

R

I play with Fisher's irises in R, I wrote a kNN classifier for one point and now I decided to write a cycle that would classify each point on the graph, I used this construction

xl <- iris[, 3:5]
for (i in seq(0.8,7.5,by=0.1)){
  for (j in seq(-1,3.5,by=0.1)){
    z <- c(i, j)
    class <- kNN(xl, z, k=6)
    points(z[1], z[2], pch = 21, bg = "white", col=colors[class], asp = 1)
  }
}

but when it comes to a real point from the sample, it is repainted into a verified one, how can I make sure that these points are skipped in the loop and not subjected to classification?