Grouping Over All Possible Combinations of Several Variables With dplyr

Question

Given a situation such as the following

library(dplyr)
myData <- tbl_df(data.frame( var1 = rnorm(100), 
                             var2 = letters[1:3] %         


        

Answer 1

Inspired by the answers by Gregor and dimitris_ps, I wrote a dplyr style function that runs summarise for all combinations of group variables.

summarise_combo <- function(data, ...) {

  groupVars <- group_vars(data) %>% map(as.name)

  groupCombos <-  map( 0:length(groupVars), ~combn(groupVars, ., simplify=FALSE) ) %>%
    unlist(recursive = FALSE)

  results <- groupCombos %>% 
    map(function(x) {data %>% group_by(!!! x) %>% summarise(...)} ) %>%
    bind_rows()

  results %>% select(!!! groupVars, everything())
}

Example

library(tidyverse)
mtcars %>% group_by(cyl, vs) %>% summarise_combo(cyl_n = n(), mean(mpg))