[R] problem in my code

[Taka Matzmoto]

Dear R-users

I wrote a small program for assigning a membership

Here is my script

sample.size <- 60

x <- rnorm(sample.size, 0, 1)
y <- rnorm(sample.size, 0, 1)

x.mean <- mean(x)
y.mean <- mean(y)
membership <- numeric(sample.size)

for (i in 1:sample.size)
    {
        if ((x[i] < x.mean) && (y[i] < y.mean))
            {
                membership[i] <<- 1
            } else {
                        if ((x[i] > x.mean) && (y[i] < y.mean))
                            {
                                membership[i] <<- 2
                            } else {
                                        if ((x[i] > x.mean) && (y[i] > 
y.mean))
                                            {
                                                membership[i] <<- 3
                                            } else
                                                {
                                                    membership[i] <<- 4
                                                }
                                   }

                    }

    }
cbind(x,y,membership)

There is an error message
"Error: object "membership" not found"
I can't figure it out.

Any help or advice on improvement for this code will be appreciated.
I konw this code is not well written at all.

Thank you

Taka