calculate mean over various subgroups: Stata vs (tidy) R

group_collapse.do

sysuse auto, clear

local groups foreign headroom rep78

foreach x in `groups' {
    preserve 
    rename `x' group_value
    collapse (mean) mean_mpg = mpg, by(group_value)
    gen group_name = "`x'"
    tempfile group`x'
    save `group`x''
    restore
}

clear
foreach x in `groups' {
    append using `group`x''
}
order group_name group_value mean_mpg
list

group_collapse.R

library(tidyverse)

mydata <- mtcars

groups <- c("cyl", "gear", "carb")

group_summarize <- function(x) {
  mydata %>% 
    rename(group_value = {{ x }}) %>% 
    group_by(group_value) %>% 
    summarize(mean_mpg = mean(mpg)) %>% 
    mutate(group_name = x)
}

map_dfr(groups, group_summarize) %>% 
  select(group_name, group_value, mean_mpg)