Including absent values in table() results in R

Question

I have a vector of integers between 0 and 5. I want to compute a histogram of counts. For example:

> y <- c(0,0,1,3,4,4)
> table(y)
y
0 1 3 4 
2 1 1 2

However, I also want the results to include the fact that there are zero 2's and zero 5's, ie. I want the returned vector to have length 6. Can I use table() for this?

Answer 1

If you convert y to a factor, the missing factor levels will also appear in the table

> y <- c(0,0,1,3,4,4)
> table(factor(y, levels=0:5))
0 1 2 3 4 5 
2 1 0 1 2 0