Parameterizing group_by %>% summarise

Question

There is a data.frame like so:

df <- data.frame("Config" = c("C1","C1","C2","C2"), "SN1" = 1:4, "SN2" = 5:8)

I'm trying to make group_by %>% summarise more generic. Here is an example that does not work:

variable <- "SN1"

df %>%
  group_by(
  Config
  ) %>%
  summarise(
    paste0(variable, ".median")=median(UQ(as.symbol(variable)))
  ) %>%
  as.data.frame() ->
  df_summary

It does not work because of paste0(variable, ".median") part.

Related question-answer Pass arguments to dplyr functions helped me to parameterize median(UQ(as.symbol(variable))) part but it does not mention the left-hand side part.

Is there a way to fix the above?

Answer 1

You can use enquo and !!

library(tidyverse)

mysumm <- function(variable){
  var <- enquo(variable)
  df %>%
    group_by(
    Config
    ) %>%
    summarise(!!paste0(variable, ".median") := median(!!var))
}

mysumm('SN1')
# # A tibble: 2 x 2
#   Config SN1.median
#   <fct>  <chr>     
# 1 C1     SN1       
# 2 C2     SN1