Categorizing the contents of a vector - r

Question

Here is my problem:
myvec <- c(1, 2, 2, 2, 3, 3,3, 4, 4, 5, 6, 6, 6, 6, 7, 8, 8, 9, 10, 10, 10)
I want to develop a function that can caterize this vector depending upon number of categories I define.
if categories 1 all newvec elements will be 1
if categories are 2 then
unique (myvec), i.e.
1 = 1, 2 =2, 3 = 1, 4 = 2, 5 =1, 6 = 2, 7 = 1, 8 = 2, 9 = 1, 10 = 2
(which is situation of odd or even numbers)
If categories are 3 then first three number will be 1:3 and then pattern will be repeated.
1 = 1, 2 = 2, 3=3, 4=1, 5 = 2, 6 = 3, 7 =1, 8 = 2, 9 = 3, 10 =1
If caterogies are 4 then first number will be 1:4 and then pattern will be repeated
1 = 1, 2 = 2, 3= 3, 4 = 4, 5 = 1, 6 = 2, 7=3, 8=4, 9 =1, 10 = 2
Similarly for n categories the first 1:n, then the pattern repeated.

Answer 1

This should do what you need, if I correctly understood the question. You can vary variable n to choose the number of groups.
myvec <- c(1, 2, 2, 2, 3, 3, 3, 4, 4, 5, 6, 6, 6, 6, 7, 8, 8, 9, 10, 10, 10)
out <- vector(mode="integer", length=length(myvec))
uid <- sort(unique(myvec))
n <- 3
for (i in 1:n) {
s <- seq(i, length(uid), n)
out[myvec %in% s] <- i
}

Answer 2

Using the recycling features of R (this gives a warning if the vector length is not divisible by n):
R> myvec <- c(1, 2, 2, 2, 3, 3, 3, 4, 4, 5, 6, 6, 6, 6, 7, 8, 8, 9, 10, 10, 10)
R> n <- 3
R> y <- cbind(x=sort(unique(myvec)), y=1:n)[, 2]
R> y
[1] 1 2 3 1 2 3 1 2 3 1
or using rep:
R> x <- sort(unique(myvec))
R> y <- rep(1:n, length.out=length(x))
R> y
[1] 1 2 3 1 2 3 1 2 3 1
Update: you could just use the modulo operator
R> myvec
[1] 1 2 2 2 3 3 3 4 4 5 6 6 6 6 7 8 8 9 10 10 10
R> n <- 4
R> ((myvec - 1) %% n) + 1
[1] 1 2 2 2 3 3 3 4 4 1 2 2 2 2 3 4 4 1 2 2 2