Refer to a function param in ggplot

ikjhgfrtyuhjk 0
Viewed 32

Attempt of a function:

plot_eval <- function(data, metric) {
  data |> 
    ggplot(aes(x = cut, y = metric)) +
    geom_point() +
    ggtitle(metric)
}

Tried with diamonds data set e.g:

plot_eval(diamonds, price)
Error in dots_list(..., title = title, subtitle = subtitle, caption = caption, :
object 'price' not found

I would like the function to run in the following way, here I create the plot directly outside of a function:

diamonds |> 
  ggplot(aes(x = cut, y = price)) +
  geom_point() +
  ggtitle('price')

Produces a plot: enter image description here

How can I call my function to get the same result:

plot_eval(diamonds, price)
ggplot2 r
2 Answers

If you want to pass columns use curlycurly {{}} and in the ggtitle to pass the string use deparse(substitute(y)). For more details see https://dplyr.tidyverse.org/articles/programming.html

plot_eval <- function(data, x, y) {
  data  %>%  
    ggplot(aes(x = {{x}}, y = {{y}})) +
    geom_point() +
    ggtitle(deparse(substitute(y)))
}

plot_eval(diamonds, cut, price)

enter image description here

TarJae0

You could do:

library(ggplot2)

plot_eval <- function(data, metric) {
  
  metric <- enquo(metric)
  
  data |> 
    ggplot(aes(x = cut, y = !!metric)) +
    geom_point() +
    ggtitle(metric)
}

plot_eval(diamonds, price)

Created on 2022-09-15 with reprex v2.0.2

Allan Cameron0
Related