ggplot2分面网格(Facet Grid)自定义各分面Y轴刻度标签方法咨询

要实现ggplot2分面网格的不同Y轴刻度自定义，最简便的方法是使用ggh4x扩展包提供的分面坐标轴独立设置功能，具体操作如下：

步骤1：安装加载所需包 #

install.packages("ggh4x")
library(ggh4x)
library(ggplot2)

步骤2：修改原有绘图代码 #

仅需要在原有代码的facet_grid层后新增facetted_pos_scales层，即可为不同分面单独设置Y轴参数，修改后的完整代码如下：

ggplot() +
  geom_violin(data = fulldfUp, aes(x = Species, y = Value),
              fill = "#ffffff", colour = "#000000", show.legend = FALSE, alpha = .9, size = .3, width = .7) +
  stat_summary(data = fulldfUp, aes(x = Species, y = Value),  
               fun = mean, geom = "point", shape = 21, size = 3.5, alpha = .9, colour = "#000000", fill = "#fc3232") +
  facet_grid(Estimate ~. , scales = "free", labeller = labeller(Estimate = ylabels)) +
  # 新增部分：为不同分面设置独立Y轴
  facetted_pos_scales(
    y = list(
      Estimate == "平均深度（Mean Depth）" ~ scale_y_continuous(breaks = 1:4, labels = paste0(1:4, "X")),
      Estimate == "保留reads百分比（Percentage of Retained Reads）" ~ scale_y_continuous(breaks = seq(10,40,10), labels = paste0(seq(10,40,10), "%"))
    )
  ) +
  scale_fill_manual(values = c("#fbb4ae", "#b3cde3", "#ccebc5", "#decbe4", "#fed9a6")) +
  scale_colour_manual(values = c("#fbb4ae", "#b3cde3", "#ccebc5", "#decbe4", "#fed9a6")) +
  theme(panel.background = element_rect(fill = "#ffffff"),
        panel.grid.major.x = element_line(color = "#ededed", linetype = "dashed", size = .00005),
        panel.grid.major.y = element_blank(),
        panel.grid.minor = element_blank(), 
        panel.border = element_blank(),
        axis.line = element_line(colour = "#000000", size = .3),
        axis.title = element_blank(),
        axis.text.x = element_text(colour = "#000000", size = 20, face = "bold", angle = 45, vjust = 1, hjust = 1),
        axis.text.y = element_text(color = "#000000", size = 20),
        axis.ticks.x = element_line(color = "#000000", size = .3),
        axis.ticks.y = element_line(color = "#000000", size = .3),
        strip.background.y = element_rect(colour = "#000000", fill = "#d6d6d6", size = 0.3),
        strip.text = element_text(colour = "#000000", size = 20, face = "bold"),
        legend.position = "top",
        legend.margin = margin(t = 0, b = 0, r = 0, l = 0),
        legend.box.margin = margin(t = 10, b = 20, r = 0, l = 0),
        legend.key = element_rect(fill = NA),
        legend.background = element_blank())

替代方案（无第三方分面扩展包） #

如果不想使用ggh4x，可以拆分绘图后用patchwork拼接：

• 分别筛选Estimate列两个取值的子集，各自独立绘制小提琴图，分别调用scale_y_continuous设置对应刻度标签
• 用patchwork包的垂直拼接语法plot1 / plot2合并两个图，调整主题保持样式一致即可。

内容的提问来源于stack exchange，提问作者George Pacheco