Add margin row totals in dplyr chain

Question

I would like to add overall summary rows while also calculating summaries by group using dplyr. I have found various questions asking how to do this, e.g. here, here, and he

Answer 1

With adorn_totals() from the janitor package:

library(janitor)
mtcars %>%
  tabyl(cyl, gear) %>%
  adorn_totals("row") 

   cyl  3  4 5
     4  1  8 2
     6  2  4 1
     8 12  0 2
 Total 15 12 5

To get from there to the "long" form in your post, add tidyr::gather() to the pipeline:

mtcars %>%
  tabyl(cyl, gear) %>%
  adorn_totals("row") %>%
  tidyr::gather(gear, n, 2:ncol(.), convert = TRUE)

     cyl gear  n
1      4    3  1
2      6    3  2
3      8    3 12
4  Total    3 15
5      4    4  8
6      6    4  4
7      8    4  0
8  Total    4 12
9      4    5  2
10     6    5  1
11     8    5  2
12 Total    5  5

Self-promotion alert, I authored this package - adding this answer b/c it's a genuinely efficient solution here.