Example of using patchwork and cowplot to arrange legends in a four panel plot.

patchwork_cowplot_example.R

# example of using cowplot and patchwork to make a plot with legends in the bottom right of a four panel plot

# load in packages
librarian::shelf(tidyverse, patchwork, cowplot)

# make a random plot with colour
p1 <- ggplot(mpg, aes(hwy, cty, col = class)) +
  geom_point()

# make other plot with colour on
p2 <- ggplot(mpg, aes(hwy, displ, col = class)) +
  geom_point()

# third plot with different legend
p3 <- ggplot(mpg, aes(displ, hwy, col = drv)) +
  geom_point()

# make patchwork
p1 + p2 + p3 + plot_layout(ncol = 2)

# try collect legends
p1 + p2 + p3 + plot_layout(ncol = 2, guides = 'collect') & theme(legend.position = 'right')
# this works but you cannot control position of the legends very well

# grab legends using cowplot
legend1 <- get_legend(p1)
legend2 <- get_legend(p3)

# put them side by side
legends <- cowplot::plot_grid(legend1, legend2, ncol = 2, align = 'v')

# make plot and turn off legend globally
p1 + p2 + p3 + legends + plot_layout(ncol = 2) & theme(legend.position = 'none')

# can also put the legend on top of each other
legends <- cowplot::plot_grid(legend1, legend2, ncol = 1, align = 'v')

p1 + p2 + p3 + legends + plot_layout(ncol = 2) & theme(legend.position = 'none')

# there are loads of otehr ways to control the layout of the plot - see https://patchwork.data-imaginist.com/articles/guides/layout.html