Return the reference or specific level of a factor

Extracts the reference or a specific level the supplied factor, returning it as a factor with the same levels as the one supplied.

Usage

ref_level(fct)

level(fct, level)

Arguments

fct

factor; the factor from which the reference or specific level will be extracted.

level

character; the specific level to extract in the case of level().

Value

A length 1 factor with the same levels as the supplied factor fct.

Examples

# \dontshow{
set.seed(1)
# }
f <- factor(sample(letters[1:5], 100, replace = TRUE))

# the reference level
ref_level(f)
#> [1] a
#> Levels: a b c d e

# a specific level
level(f, level = "b")
#> [1] b
#> Levels: a b c d e

# note that the levels will always match the input factor
identical(levels(f), levels(ref_level(f)))
#> [1] TRUE
identical(levels(f), levels(level(f, "c")))
#> [1] TRUE