ggplot2图例优化：仅保留颜色块，移除边框与内部标记

要实现你想要的图例样式（无边框、纯填充方块无内部标记），我们可以通过修改图例的主题设置和覆盖图例的美学映射来完成。以下是调整后的完整代码：

library(ggplot2)
library(plyr)

N <- 25
IV1 <- c('level1', 'level1', 'level1', 'level1', 'level1', 'level1', 'level1', 'level1', 'level2', 'level2', 'level2', 'level2', 'level2', 'level2', 'level2', 'level2')
IV2 <- c('level1', 'level1', 'level1', 'level1', 'level2', 'level2', 'level2', 'level2', 'level1', 'level1', 'level1', 'level1', 'level2', 'level2', 'level2', 'level2')
IV3 <- c('level1', 'level1', 'level2', 'level2', 'level1', 'level1', 'level2', 'level2', 'level1', 'level1', 'level2', 'level2', 'level1', 'level1', 'level2', 'level2')
IV4 <- c('level1', 'level2', 'level1', 'level2', 'level1', 'level2', 'level1', 'level2', 'level1', 'level2', 'level1', 'level2', 'level1', 'level2', 'level1', 'level2')

exampleData <- data.frame(subNum = rep(1:N, each = 16),
                          DV = rnorm(N*length(IV1)),
                          IV1 = factor(rep(IV1, N), levels = c('level1', 'level2')),
                          IV2 = factor(rep(IV2, N), levels = c('level1', 'level2')),
                          IV3 = factor(rep(IV3, N), levels = c('level1', 'level2')),
                          IV4 = factor(rep(IV4, N), levels = c('level1', 'level2')))

exampleDataSummary <- ddply(exampleData, c('IV1', 'IV2', 'IV3', 'IV4'),
                            summarise,
                            meanDV = mean(DV),
                            N = length(DV),
                            sdDV = sd(DV),
                            seDV = sdDV/sqrt(N))

plot <- ggplot(exampleData, aes(y = DV, x = IV1, fill = IV2))

plot + facet_grid(IV3 ~ IV4) +
  geom_dotplot(binaxis = "y", alpha = 0.7, stackdir = "center", position = position_dodge(width = 1)) +
  geom_violin(aes(y = DV, fill = IV2), alpha = 0.5, position = position_dodge(width = 1)) +
  geom_point(aes(y = meanDV, x = IV1), data = exampleDataSummary, position = position_dodge(width = 1)) +
  geom_errorbar(aes(y = meanDV, ymin = meanDV - seDV, ymax = meanDV + seDV), 
                color = "black", width = 0.2, data = exampleDataSummary, 
                position = position_dodge(width = 1)) +
  # 调整图例美学：去掉内部标记，只保留填充方块
  guides(fill = guide_legend(override.aes = list(shape = NA, color = NA))) +
  # 去掉图例边框和背景
  theme(
    legend.background = element_blank(),
    legend.key = element_blank(),
    legend.box.background = element_blank()
  )

关键修改说明： #

1. 移除图例内部标记：
   使用guides(fill = guide_legend(override.aes = list(shape = NA, color = NA)))覆盖了图例的美学映射：

   • shape = NA：隐藏了图例中来自geom_point和geom_dotplot的圆形标记
   • color = NA：确保图例方块没有额外的边框线条

2. 移除图例边框：
   通过theme()中的三个设置彻底清除图例的边框和背景：

   • legend.background = element_blank()：移除整个图例区域的背景和边框
   • legend.key = element_blank()：移除每个图例项的背景和边框
   • legend.box.background = element_blank()：移除图例容器的边框（如果存在）

这样修改后，你的图例就会变成纯填充的无边框方块，完全符合你想要的样式。

内容的提问来源于stack exchange，提问作者JAQuent