Totals and subtotals with dplyr and bind_rows

dplyr_subtotals.R

library(dplyr)

set.seed(123)

dat <- tibble(main_grp = rep(c("a", "b"), each = 4),
              sub_grp = rep(c("x", "y"), 4),
              value = rnorm(8))

dat %>% 
  bind_rows(., mutate(dat, sub_grp = "subtotal")) %>%
  bind_rows(., mutate(dat, main_grp = "total", sub_grp = "")) %>% 
  group_by(main_grp, sub_grp) %>% 
  summarise(sum = sum(value)) %>% 
  arrange(main_grp,
          main_grp == "total",
          sub_grp  == "subtotal")

#> `summarise()` has grouped output by 'main_grp'. You can override using the `.groups` argument.
#> # A tibble: 7 x 3
#> # Groups:   main_grp [3]
#>   main_grp sub_grp       sum
#>   <chr>    <chr>       <dbl>
#> 1 a        "x"         0.998
#> 2 a        "y"        -0.160
#> 3 a        "subtotal"  0.839
#> 4 b        "x"         0.590
#> 5 b        "y"         0.450
#> 6 b        "subtotal"  1.04 
#> 7 total    ""          1.88