Keep just one key/legend in patchwork ggplots

Question

The following code produces a patchwork plot:

library(tidyverse)
library(patchwork)
mtboxes <- mtcars |> 
  select(-cyl) |> 
  imap(~ ggplot() +
        geom_boxplot(aes(y = .x, fill = factor(mtcars$cyl))) +
        labs(title = .y, x = NULL, y = NULL))
mtboxes <- mtboxes |> Reduce(`+`, x = _)
mtboxes

There's a legend on each boxplot which is repetitive. I would like to include one of these legends, ideally along the top, right side or bottom, then clear from the rest. How can I do that?

Answer 1

Use + plot_layout(guides = "collect"):

library(tidyverse)
library(patchwork)

mtboxes <- mtcars |>
  select(-cyl) |>
  imap(~ ggplot() +
    geom_boxplot(aes(y = .x, fill = factor(mtcars$cyl))) +
    labs(title = .y, x = NULL, y = NULL))
mtboxes <- mtboxes |> Reduce(`+`, x = _) + plot_layout(guides = "collect")

mtboxes