ggarrange合并绘图后ggsave导出PNG图例周边空白缺失问题求助

以下几种方法可快速解决该问题，让图例及周边空白区域变为白色，适配LaTeX的显示需求：

方法1：ggsave导出时直接指定背景色 #

这是最简便的方案——PNG格式默认背景透明，只需在ggsave中添加bg="white"参数，即可强制填充所有空白区域为白色：

ggsave(uni11, filename = "file.png", path = "~/path", 
       width = 24, height = 8, units = "cm", dpi=700,
       bg = "white")  # 新增背景色参数

方法2：为子图设置统一背景主题 #

在每个ggplot子图的theme里，明确设置子图背景和图例背景为白色，从源头确保区域颜色正确：

g11 = ggplot() +
  geom_smooth(se = F, data = df, aes(x = sc, y = changes, color = factor(nr), group = factor(nr))) +
  scale_color_viridis(discrete = TRUE, option = "D")+
  scale_fill_viridis(discrete = TRUE) +
  theme(
    legend.position = "bottom",
    plot.background = element_rect(fill = "white", color = NA),  # 子图背景设为白色
    legend.background = element_rect(fill = "white", color = NA)  # 图例背景设为白色
  ) 

g21 = ggplot() +
  geom_smooth(se=F, data = df, aes(x = sc, y = changes, color = factor(nr), group = factor(nr))) +
  scale_color_viridis(discrete = TRUE, option = "D")+
  scale_fill_viridis(discrete = TRUE) +
  theme(
    legend.position = "bottom",
    plot.background = element_rect(fill = "white", color = NA),
    legend.background = element_rect(fill = "white", color = NA)
  ) 

uni11=ggarrange(g11, g21, ncol=2, common.legend = TRUE, legend="bottom")
ggsave(uni11, filename = "file.png", path = "~/path", width = 24, height = 8, units = "cm", dpi=700)

方法3：通过ggarrange设置整体背景 #

利用ggpubr包ggarrange自带的background参数，为合并后的整个图形统一设置白色背景：

uni11=ggarrange(g11, g21, ncol=2, common.legend = TRUE, legend="bottom",
                background = element_rect(fill = "white", color = NA))  # 设置整体背景
ggsave(uni11, filename = "file.png", path = "~/path", width = 24, height = 8, units = "cm", dpi=700)

优先推荐方法1，操作简单且能覆盖所有空白区域的填充需求。

内容的提问来源于stack exchange，提问作者Karl Seidl