Calculate total values when summarising grouped data

Question

I have a dataframe where I have grouped data, I am running summary statistics by group but also want to get summary statistics for everything combined. Is there a simpler way of doing it than doing it twice and combining like follows?

dataDF <- data.frame(
  group = rep(c('a', 'b', 'c'), 10),
  value1 = rnorm(30),
  value2 = 1:30
)

grouped <- dataDF %>%
  group_by(group) %>% 
  summarise(
    mean1 = mean(value1),
    mean2 = mean(value2),
    sd1 = sd(value1),
    sd2 = sd(value2),
    max1 = max(value1),
    max2 = max(value2)
    )

total <- dataDF %>%
  summarise(
    mean1 = mean(value1),
    mean2 = mean(value2),
    sd1 = sd(value1),
    sd2 = sd(value2),
    max1 = max(value1),
    max2 = max(value2)
  )

combined <- rbind(
  grouped,
  data.frame(
    group = 'All',
    total
  ))

> combined
# A tibble: 4 x 7
  group  mean1 mean2   sd1   sd2  max1  max2
  <fct>  <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
1 a      0.336  14.5 1.15   9.08  1.98    28
2 b     -0.215  15.5 1.17   9.08  1.30    29
3 c      0.332  16.5 0.874  9.08  2.19    30
4 All    0.151  15.5 1.07   8.80  2.19    30

Answer 1

I have written a function to do this

summarise_with_total <- function(data, func, ...){

  # Gets the cohorts which the DF is grouped by
  cohorts <- groups(data)

  # Results split by cohorts
  split <- data %>% 
    func(...) %>% 
    data.frame()

  # results combined
  combined <- data.frame(
    setNames(data.frame(matrix(data = "All",
                               ncol = length(cohorts),
                               nrow = 1)),
             cohorts),
    ungroup(data) %>% 
      func(...)
  )

  return(rbind(split, combined))

}

dataDF %>% 
  group_by(group) %>% 
  summarise_with_total(summarise_at,
                      .vars = c('value1', 'value2'), 
                      .funs = funs(mean, sd, max))