use where in select and across with custom function

select_where.R

library(tidyverse)

contains_comma <- function(x) {
  if (is.character(x) || is.factor(x)) {
    any(str_detect(x, ","))  
  } else {FALSE}
}

gss_cat %>%
  select(where(contains_comma))

gss_cat %>% 
  transmute(across(where(contains_comma)))

gss_cat %>% 
  mutate(across(where(contains_comma)),
         .keep = "none")