Why for loop only shows result of last loop

Question

I have this sample matrix:

  X1 X2 X3 X4
1  F  F  F  F
2  C  C  C  C
3  D  D  D  D
4 A# A# A#  A

And I\'m trying to use a for loop to get the n

Answer 1

This should be sufficient:

y <- read.csv(file)
x <- numeric(4)
for(i in 1:4) {
    x[i] <- length(unique(y[, i]))
}

or:

x <- apply(y,2,function(x) length(unique(x)))