Function... malfunction(malcoder!), including group_by and export

Question

In R, I am trying to turn the code below into a function (with a parameter variable instead of gender).

res_gender <- payments %>%
                group_by(yrmon,gender) %>%
             summarise_at(vars(nbpol,nbtrans,member_revenue,untenm,untem),
list(name = sum)) 

write.table(res_gender, file="gender.csv",sep=",",row.names=F)

Here is my attempt (for the 1st part) and the error I get:

resum <- function(grpvar) { 
      res_grpvar <- payments %>%
                     group_by(yrmon,grpvar) %>%
             summarise_at(vars(nbpol,nbtrans,member_revenue,untenm,untem),
list(name = sum)) 
} 

resum(gender)

Error: Column grpvar is unknown

even if I give a dummy name to the output table w/o variable in its name.

Questions:

1. how to write the 'resum' function in order get the exact same result as in the initial code?
2. I have no clue how to write the part for the export (with datafile parametered), any suggestion?

Thanks in advance, merci!

Answer 1

When you pass column name as function argument you have to use non-standard evaluation of some sort. If you pass unquoted argument in a function use {{}} to evaluate as column name.

library(dplyr)

resum <- function(data, grpvar) { 
  col <- deparse(substitute(grpvar))
  
  res_grpvar <- data %>%
    group_by(yrmon,{{grpvar}}) %>%
    summarise(across(c(nbpol,nbtrans,member_revenue,untenm,untem),
              sum, .names = '{col}_name'))
  
  write.table(res_gender, file=paste0(col, '.csv'),sep=",",row.names=F)
} 

resum(payments, gender)