Creating a function with ggplot in body and producing two plot outputs per call

Question

I am trying to create a function that contains ggplot in the function body, and yields two or more plots per call.

I have taken the approach of initially testing my function with only one plot being produced, and it has worked. I have called my plots outside of the function to ensure I am coding them correctly, and they work on an individual basis. The following code only produces a single barplot with the y axis scaled to 1, with no error:

library(tidyverse)

cat_plots <- function(dat, var1, var2){

  nums <- ggplot(dat) + geom_bar(aes_string(var1, fill = var2)) 

  props <- ggplot(dat) + 
    geom_bar(aes_string(var1, fill = var2), position = "fill")

  nums
  props
}

cat_plots(diamonds, "cut", "clarity")

The expected result is a plot for nums and a plot for props - I am trying to simultaneously produce two plots, with raw counts and with proportions, in order to easily compare between the two. I don't get an error returned. I only get the last barplot, showing only proportions. The expected barplot with counts in the y axis does not appear at all.

R functions are only allowed to return 1 object. If you want to return multiple objects, put them in a list, list(nums, props). If you want to display both plots (I'd recommend giving the user an option to disable this), explicitly print() them in the function. print(nums); print(props). — Gregor Thomas
– Gregor Thomas, Commented Jun 6, 2019 at 19:01

yake84 · Accepted Answer · 2019-06-06 23:59:05Z

1

Would a solution like this work for you? grid.arrange() is an easy way to print out two plots at once.

library(tidyverse)

cat_plots <- function(dat, var1, var2){

  nums <- ggplot(dat) + geom_bar(aes_string(var1, fill = var2)) 

  props <- ggplot(dat) + 
    geom_bar(aes_string(var1, fill = var2), position = "fill")

  gridExtra::grid.arrange(nums, props, ncol = 1)
}

cat_plots(diamonds, "cut", "clarity")

answered Jun 6, 2019 at 23:59

yake84

3,3163 gold badges24 silver badges40 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Creating a function with ggplot in body and producing two plot outputs per call

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related