I have a pseudo table like this.

dat <- data.frame(
  colA = c("factor1", "factor1", "factor1", "factor1","factor2", "factor2","factor2", "factor2"),
  colB = c("a", "a", "a", NA, "a", "a", "a", NA), 
  colC = c(1, 1, 1, 5, 2,4,5,6))
dat
     colA colB colC
1 factor1    a    1
2 factor1    a    1
3 factor1    a    1
4 factor1 <NA>    5
5 factor2    a    2
6 factor2    a    4
7 factor2    a    5
8 factor2 <NA>    6

I want to sum the values in colC, group_by by colA, but only including rows where colB does not have (NA). After that, I’d like to calculate the frequency of the resulting sums.

My desired outputs will be:

Any suggestions for this? Thanks in advance!