How to get the mode of a group in summarize in R

Question

I want to compare costs of CPT codes from two different claims payers. Both have par and non par priced providers. I am using dplyr and modeest::mlv

Answer 1

I use this approach:

df <- data.frame(groups = c("A", "A", "A", "B", "B", "C", "C", "C", "D"), nums = c("1", "2", "1", "2", "3", "4", "5", "5", "1"))

which looks like:

 groups nums
  A    1
  A    2
  A    1
  B    2
  B    3
  C    4
  C    5
  C    5
  D    1

Then I define:

mode <- function(codes){
  which.max(tabulate(codes))
}

and do the following:

mds <- df %>%
  group_by(groups) %>%
  summarise(mode = mode(nums))

giving:

  groups  mode
 A          1
 B          2
 C          5
 D          1