R在总结中应用2个不同的函数

我有以下改装过的地铁车辆：

mtcars2您可以使用：

library(dplyr)

mtcars2 %>% 
  group_by(vs) %>% 
  summarise_at(vars(-group_cols()), 
              list(Total = ~sum(., na.rm = TRUE), n = length))


# A tibble: 2 x 5
#     vs cyl_Total disp_Total cyl_n disp_n
#  <dbl>     <dbl>      <dbl> <int>  <int>
#1     0       128      5529.    18     18
#2     1        64      1854.    14     14

我们也可以使用
data.table

library(data.table)
as.data.table(mtcars2)[, c(lapply(.SD, sum, na.rm = TRUE), .(n = .N)) , vs]

mtcars2 %>% 
  mutate(n = 1) %>%
  group_by(vs) %>% 
  summarise_at(vars(-group_cols()), list(Total = ~sum(., na.rm = TRUE)))


# A tibble: 2 x 4
#     vs cyl_Total disp_Total n_Total
#  <dbl>     <dbl>      <dbl>   <dbl>
#1     0       128      5529.      18
#2     1        64      1854.      14

library(data.table)
as.data.table(mtcars2)[, c(lapply(.SD, sum, na.rm = TRUE), .(n = .N)) , vs]