R - add column that counts sequentially within groups but repeats for duplicates

Question

I\'m looking for a solution to add the column \"desired_result\" preferably using dplyr and/or ave(). See the data frame here, where the group is \"section\" and the unique

Answer 1

dense_rank it is

library(dplyr)
df %>% 
  group_by(section) %>% 
  mutate(desire=dense_rank(exhibit))
#  section exhibit desired_result desire
#1       1       a              1      1
#2       1       b              2      2
#3       1       c              3      3
#4       1       c              3      3
#5       2       a              1      1
#6       2       b              2      2
#7       2       b              2      2
#8       2       c              3      3