3.6 group_by e summarise

cjsg %>% 
  select(id_processo, dt_decisao) %>% 
  mutate(dia_da_semana = weekdays(dmy(dt_decisao))) %>% 
  group_by(dia_da_semana) %>% 
  summarise(n = n())

#> # A tibble: 5 x 2
#>   dia_da_semana     n
#>   <chr>         <int>
#> 1 quarta         1530
#> 2 quinta         6044
#> 3 segunda        1537
#> 4 terça          2555
#> 5 <NA>             65