Passing in column name as argument

Question

I'm trying to create a function where I can pass in column names as an argument. I've seen some other examples like this post on passing column names to a function but I'm getting an error:

Error: Column column is unknown

Here is my data in my csv:

Role
1 Primary
2 Secondary
3 Primary
4 Primary

Here is my code:

mydata = read.csv("EA5.csv")

my_bar_chart <- function(data, column, title){
  column<-eval(substitute(column),data, parent.frame())
  toReturn <- data %>% 
    group_by(column) %>% 
    summarize(count = n()) %>% 
    mutate(percent = count/sum(count), column = reorder(column, -count, FUN=identity)) %>%
    ggplot(aes(x=column, y=count)) +
    xlab(title)+
    geom_col() +
    geom_text(aes(label = paste0(round(100 * percent, 1), "%")))
  return(toReturn)
}

p1 <- my_bar_chart(mydata, Role, "EA5 Controller Role")

grid.arrange(p1)

Answer 1

In the latest version of rlang we can use 'curly-curly' for this ({{column}}):

mydata = iris

my_bar_chart <- function(data, column, title){
  toReturn <- data %>% 
    group_by({{column}}) %>% 
    summarize(count = n()) %>% 
    mutate(percent = count/sum(count), column = reorder({{column}}, -count, FUN=identity)) %>%
    ggplot(aes(x=column, y=count)) +
    xlab(title)+
    geom_col() +
    geom_text(aes(label = paste0(round(100 * percent, 1), "%")))
  return(toReturn)
}

p1 <- my_bar_chart(mydata, Species, "EA5 Controller Role")