collect guides when legend.position="bottom"

[schochastics]

I'd like to center a common legend below two plots (see reprex below).
This does not seem to work atm (at least not how I thought it could work), and I somehow expect/fear that this is technically not possible?!?

library(tidyverse)
library(patchwork)

set.seed(17)
dat1 <- tibble(x = rep(1:5,2),
              y = sample(1:10,10,replace = T),
              grp = rep(c("A","B"),each=5))

dat2 <- tibble(x = rep(1:5,2),
              y = sample(1:10,10,replace = T),
              grp = rep(c("A","B"),each=5))


p1 <- ggplot(dat1,aes(x,y)) + geom_line(aes(col=grp))
p2 <- ggplot(dat2,aes(x,y)) + geom_line(aes(col=grp))

p1 + p2 + plot_layout(guides = "collect")

p3 <- ggplot(dat1,aes(x,y)) + 
   geom_line(aes(col=grp)) + 
   theme(legend.position = "bottom")

p4 <- ggplot(dat2,aes(x,y)) + 
   geom_line(aes(col=grp)) + 
   theme(legend.position = "bottom")

p3 + p4 + plot_layout(guides = "collect")

[thomasp85]

You just need to make sure that the theming of the patchwork has legend.position = 'bottom' as well. This can be done using either the theme argument in plot_annotation(), or by & a theme object to it which will apply the theme to both the patchwork as well as to all subplots:

p1 + p2 + plot_layout(guides = "collect") & theme(legend.position = 'bottom')

[melissagwolf]

This helped so much. If you write the code as + theme instead of & theme, the legend position will not go where it is specified. The & is key.

[MatthieuStigler]

Awesome! Might be worth emphasizing this point in the (great) online manual on plot_layout. As a newcomer, I came into the exact same issue.

Thanks!

[costavale]

is the manual position of the legend still not possible?

[melissagwolf]

Hi Thomas,

It seems like guides=collect might not be working anymore? I'm re-running the reprex from the first post and I'm getting the same legend twice. However, the position is still working.

Thanks!

Melissa

[llrs]

Hi Melissa @melissagwolf,

Are you using R 4.0.0 ? This is a know bug #170 (Unless your session Information says something different)

Lluís

[melissagwolf]

Yep, using 4.0.0. Thank you for the quick response!

[nahorp]

This helped so much. If you write the code as + theme instead of & theme, the legend position will not go where it is specified. The & is key.

Thank. you. so. much. you are a godsend

[costavale]

You just need to make sure that the theming of the patchwork has legend.position = 'bottom' as well. This can be done using either the theme argument in plot_annotation(), or by & a theme object to it which will apply the theme to both the patchwork as well as to all subplots:

p1 + p2 + plot_layout(guides = "collect") & theme(legend.position = 'bottom')

What if I don't want to apply the theme to all the subplots?
In other words, I want to have the "collected" legend at the centre bottom of the first two plots, but not for the third one in the first line:
(((p1|p2) + plot_layout(guides = "collect") & theme(legend.position = "bottom"))|p2 + plot_layout(guides = "keep"))/(p1|p2)

I cannot manage to have this working. any solution?

[krassowski]

I cannot manage to have this working. any solution?

yup, this is pretty bad when including ggraph or circular visualisation which greatly benefit from theme_void() while other panels are using non-void themes. One thing I tried was manually specifying guide_area() but this did not work because the legend box was in always in vertical orientation (ignoring legend.box='horizontal').

[OlivaresLD]

What if I don't want to apply the theme to all the subplots? In other words, I want to have the "collected" legend at the centre bottom of the first two plots, but not for the third one in the first line: (((p1|p2) + plot_layout(guides = "collect") & theme(legend.position = "bottom"))|p2 + plot_layout(guides = "keep"))/(p1|p2)

I cannot manage to have this working. any solution?

@costavale In my case, I found two options, one not very fancy, but working and also a downgrading option. So, you can

1. use plot_annotation() like this:

p1 + p2 + plot_layout(ncol = 2, guides = "collect") +
plot_annotation(theme = theme_minimal() +
theme(legend.position = "bottom"))

or

2. downgrade ggplot2 from 4.x.x to 3.5.2 and run again, this seems to fix the conflict with patchwork