levels provides access to the levels attribute of a variable. The first form returns the value of the levels of its argument and the second sets the attribute.
levels(x)
levels(x) <- value| Parameter | Description |
|---|---|
x |
an object, for example a factor. |
value |
A valid value for levels(x). For the default method, NULL or a character vector. For the factor method, a vector of character strings with length at least the number of levels of x, or a named list specifying how to rename the levels. |
# NOT RUN {
## assign individual levels
x <- gl(2, 4, 8)
levels(x)[1] <- "low"
levels(x)[2] <- "high"
x
## or as a group
y <- gl(2, 4, 8)
levels(y) <- c("low", "high")
y
## combine some levels
z <- gl(3, 2, 12, labels = c("apple", "salad", "orange"))
z
levels(z) <- c("fruit", "veg", "fruit")
z
## same, using a named list
z <- gl(3, 2, 12, labels = c("apple", "salad", "orange"))
z
levels(z) <- list("fruit" = c("apple","orange"),
"veg" = "salad")
z
## we can add levels this way:
f <- factor(c("a","b"))
levels(f) <- c("c", "a", "b")
f
f <- factor(c("a","b"))
levels(f) <- list(C = "C", A = "a", B = "b")
f
# }