Create a ranking variable with dplyr?
Suppose I have the following data
df = data.frame(name=c("A", "B", "C", "D"), score = c(10, 10, 9, 8))
I want to add a new column with the ranking. This is what I'm doing:
df %>% mutate(ranking = rank(score, ties.method = 'first'))
# name score ranking
# 1 A 10 3
# 2 B 10 4
# 3 C 9 2
# 4 D 8 1
However, my desired result is:
# name score ranking
# 1 A 10 1
# 2 B 10 1
# 3 C 9 2
# 4 D 8 3
Clearly rank
does not do what I have in mind. What function should I be using?
It sounds like you're looking for dense_rank
from "dplyr" -- but applied in a reverse order than what rank
normally does.
Try this:
df %>% mutate(rank = dense_rank(desc(score)))
# name score rank
# 1 A 10 1
# 2 B 10 1
# 3 C 9 2
# 4 D 8 3
Other solution when you need to apply the rank to all variables (not just one).
df = data.frame(name = c("A","B","C","D"),
score=c(10,10,9,8), score2 = c(5,1,9,2))
select(df, -name) %>% mutate_all(funs(dense_rank(desc(.))))