| levels {base} | R Documentation |
levels provides access to the levels attribute of factor.
The first form prints the levels of the observations
and the second sets the levels.
In this case,
value must be a vector of character strings with
length equal to the number of levels of x.
To find out how many levels a factor has user the function
nlevels.
levels(x)
levels(x) <- value
factor, nlevels.