如何移除ggplot2中geom_rect的绿色轮廓线？

问题描述 #

使用ggplot2绘制图表时，geom_rect元素出现绿色边框，尝试在aes()中设置color=NA未解决问题，如何移除该轮廓线？

问题原因 #

代码在ggplot()的全局美学映射（aes()）中绑定了color到domain变量，geom_rect会继承这个全局的color属性。之前在aes()里设置color=NA无效，是因为这属于映射设置，而非直接指定元素的颜色属性，无法覆盖全局的color映射。

解决方案 #

提供两种可行方法：

方法一：将color映射移到需要的geom中

把全局aes()里的color和Group移到geom_errorbar和geom_point的aes()中，让geom_rect不继承全局颜色映射：

library(ggplot2)
library(tidyverse)
mydat <- data.frame(mean = c(23, 24, 15, 27, 18, 19, 23, 20, 32),
                    lower = c(20, 19, 13, 15, 14, 18, 20, 17, 20),
                    upper = c(25, 29, 17, 39, 22, 20, 26, 23, 40),
                    class = c("A", "B", "C", "A", "B", "C", "A", "B", "C"),
                    domain = c("North", "North", "North", "West", "West", "West", "South", "South", "South"),
                    stripe = c(1, 0, 1, 1, 0, 1, 1, 0, 1))
mydat$class <- as.factor(mydat$class)
mydat$domain <- as.factor(mydat$domain)
mydat$stripe <- as.factor(mydat$stripe)

colour_palette <- scales::hue_pal()(3)

p <- mydat %>%
  ggplot(aes(x = mean, y = fct_reorder(.f = class, .x = upper, .fun = max),
             xmin = lower, xmax = upper)) + # 移除全局的color和Group映射
  geom_errorbar(aes(color = fct_reorder(.f = domain, .x = upper, .fun = max),
                    Group = fct_reorder(.f = domain, .x = upper, .fun = max)),
                width = 0.1, position = position_dodge(width = 0.5)) + 
  geom_rect(aes(ymin = 0.5, ymax = 1.5, xmin = -Inf, xmax = Inf, 
                fill = stripe), alpha = 0.1) +
  geom_rect(aes(ymin = 2.5, ymax = 3.5, xmin = -Inf, xmax = Inf, 
                fill = stripe), alpha = 0.1) +
  scale_fill_manual(values = c("grey", "transparent")) +
  theme_light(base_size = 18) + 
  geom_point(aes(color = fct_reorder(.f = domain, .x = upper, .fun = max),
                 Group = fct_reorder(.f = domain, .x = upper, .fun = max)),
             position = position_dodge(width = 0.5)) +
  xlab("") +
  ylab("") +
  scale_color_manual(values = c("North" = colour_palette[1],
                                "South" = colour_palette[2],
                                "West" = colour_palette[3]),
                     name = "Domain") +
  guides(fill = "none")
p

方法二：给geom_rect显式设置color=NA

直接在geom_rect的参数中（而非aes()内部）设置color=NA，覆盖全局颜色映射：
修改原代码中的geom_rect部分为：

geom_rect(aes(ymin = 0.5, ymax = 1.5, xmin = -Inf, xmax = Inf, 
              fill = stripe), alpha = 0.1, color = NA) +
geom_rect(aes(ymin = 2.5, ymax = 3.5, xmin = -Inf, xmax = Inf, 
              fill = stripe), alpha = 0.1, color = NA) +

内容的提问来源于stack exchange，提问作者Adrian