将因素合并为一个列表

Question

I have some data about the title of faculties in our college

I want to find all the titles and only list the ones that are unique, eg Professor, Assistant Teaching Professor, Instructor.

For instance. make "Distinguished Professor' and 'professor' have the same factor "professor"

Simply, it just like combine two factors to one factor

Answer 1

If I have a data set with 5 factor levels, I can change the levels by just renaming those columns:

set.seed(23)
x <- factor(sample(letters[1:5], 20, replace = TRUE))
x
#  [1] c b b d e c e e e e e d b b e a c c e d
# Levels: a b c d e
levels(x)[3] <- "new_level"
x
#  [1] a b b d e a e e e e e d b b e a a a e d
# Levels: a b d e

The number of levels will automatically be reduced, as shown.