使用ggplot与ggarrange时如何避免图例框被截断？

这是Mac环境下ggpubr包的ggarrange函数在处理带边框的公共图例时的布局计算bug，单独绘图没问题，合并时就会截断右边框。试试下面几个可行的解决办法：

办法1：给图例框加右边内边距 #

手动给图例框增加右侧内边距，让布局计算时预留足够空间显示完整边框：

library(ggplot2)
library(ggpubr)

p1 <- ggplot(mtcars, aes(x = mpg, y = disp, color = as.factor(am))) +
  geom_point() +
  theme(
    legend.box.background = element_rect(color = "black", size = 1),
    legend.box.margin = margin(r = 5)  # 增加右侧内边距，数值可按需调整
  )

p2 <- ggplot(mtcars, aes(x = hp, y = disp, color = as.factor(am))) +
  geom_point() +
  theme(
    legend.box.background = element_rect(color = "black", size = 1),
    legend.box.margin = margin(r = 5)
  )

ggarrange(p1, p2, common.legend = T, legend = "right")

办法2：换用patchwork包合并图表 #

patchwork在图表布局和图例处理上比ggarrange更稳健，完全可以替代ggarrange的功能：

library(ggplot2)
library(patchwork)

p1 <- ggplot(mtcars, aes(x = mpg, y = disp, color = as.factor(am))) +
  geom_point() +
  theme(legend.box.background = element_rect(color = "black", size = 1))

p2 <- ggplot(mtcars, aes(x = hp, y = disp, color = as.factor(am))) +
  geom_point() +
  theme(legend.box.background = element_rect(color = "black", size = 1))

# 合并图表并统一收集图例到右侧
(p1 + p2) + plot_layout(guides = "collect") & theme(legend.position = "right")

办法3：手动调整图例宽度 #

先提取图例对象，手动加宽后再传入ggarrange：

library(ggplot2)
library(ggpubr)

p1 <- ggplot(mtcars, aes(x = mpg, y = disp, color = as.factor(am))) +
  geom_point() +
  theme(legend.box.background = element_rect(color = "black", size = 1))

p2 <- ggplot(mtcars, aes(x = hp, y = disp, color = as.factor(am))) +
  geom_point() +
  theme(legend.box.background = element_rect(color = "black", size = 1))

# 提取图例
leg <- get_legend(p1)
# 手动加宽图例宽度，数值按需调整
leg$width <- unit(leg$width + unit(5, "pt"), "pt")

# 合并时传入调整后的图例，同时隐藏子图自身的图例
ggarrange(p1 + theme(legend.position = "none"), 
          p2 + theme(legend.position = "none"), 
          legend.grob = leg,
          legend = "right")

内容的提问来源于stack exchange，提问作者J. Doe