fct_recode: Change factor levels by hand
In sindribaldur/poorcats: Tools for Working with Categorical Variables (Factors)

Change factor levels by hand

1	fct_recode(.f, ...)

`.f`	A factor (or character vector).
`...`	<`dynamic-dots`> A sequence of named character vectors where the name gives the new level, and the value gives the old level. Levels not otherwise mentioned will be left as is. Levels can be removed by naming them `NULL`.

x <- factor(c("apple", "bear", "banana", "dear"))
fct_recode(x, fruit = "apple", fruit = "banana")

# If you make a mistake you'll get a warning
fct_recode(x, fruit = "apple", fruit = "bananana")

# If you name the level NULL it will be removed
fct_recode(x, NULL = "apple", fruit = "banana")

# Wrap the left hand side in quotes if it contains special variables
fct_recode(x, "an apple" = "apple", "a bear" = "bear")

# When passing a named vector to rename levels use !!! to splice
x <- factor(c("apple", "bear", "banana", "dear"))
levels <- c(fruit = "apple", fruit = "banana")
fct_recode(x, !!!levels)