调整ggplot2分面饼图的面板标签及坐标轴刻度位置

问题1：面板标签与饼图重叠 #

你的facet标签（如Weed-Community 1）和饼图出现重叠，一是因为饼图占据了面板过多空间，二是标签位置参数设置有误（你之前错误使用了strip.text.y，但横向分面需要调整strip.text.x）。可以通过以下方式解决：

• 缩小饼图宽度，同时扩大x轴范围，给饼图外围留出更多空间
• 调整面板标签的垂直位置和底部边距，让标签远离饼图

修改代码中的绘图部分：

pc <- ggplot(data_of_weeds, 
            aes(x = "", y = Plantdensity, fill = Specie))+
  geom_bar(width = 0.8, stat="identity", color = "black") + # 减小bar宽度，让饼图更紧凑
  xlim(-1.2, 1.2) + # 扩大x轴范围，给饼图周围预留空间
  coord_polar("y", start = 0) + 
  facet_grid(.~ Cluster, labeller = as_labeller(tickname))

然后调整面板标签的样式：

pc1 <- pc + tema_piechart + 
  theme(strip.background.x = element_rect(fill="white"),
        strip.text.x = element_text(vjust = 2, margin = margin(b = 10))) # 向下移动标签并增加底部边距

问题2：坐标轴刻度与线条贴合过近 #

y轴刻度（0、50、100、150）与黑色轴线距离过近，只需给刻度标签添加右侧边距即可。在你的tema_piechart主题中修改axis.text.y参数：

tema_piechart <- theme (
  panel.background = element_blank(),
  axis.title.x = element_text(family = "Arial",color = "black"),
  axis.line = element_line(colour = "black"),
  text = element_text(size = 20),
  axis.title.y = element_blank(),
  axis.ticks.length.y = unit(0, "cm"),
  legend.position = "none",
  panel.grid.major = element_line(colour = "black"),
  axis.text = element_text(color = "black", size = 10),
  axis.text.y = element_text(margin = margin(r = 8)) # 给y轴刻度标签添加右侧边距，拉开与线条的距离
)

完整修改后的代码 #

library(ggplot2)
library(ggpubr)
library(extrafont)
library(readxl)

Specie <- c("Avena spp", "Avena spp","Avena spp", "Ranunculus spp", "Ranunculus spp",
            "Ranunculus spp", "Rumex acetosa spp","Rumex acetosa spp","Rumex acetosa spp")
Plantdensity <- c(140, 100, 30, 29, 32, 16, 10, 5,2)
Cluster <- c("Wc1", "Wc2","Wc3","Wc1", "Wc2","Wc3","Wc1", "Wc2","Wc3")
data_of_weeds <- data.frame(Specie, Plantdensity,Cluster)

tickname <- c("Wc1" = "Weed-Community 1",
              "Wc2" = "Weed-Community 2", 
              "Wc3" = "Weed-Community 3")

tema_piechart <- theme (
  panel.background = element_blank(),
  axis.title.x = element_text(family = "Arial",color = "black"),
  axis.line = element_line(colour = "black"),
  text = element_text(size = 20),
  axis.title.y = element_blank(),
  axis.ticks.length.y = unit(0, "cm"),
  legend.position = "none",
  panel.grid.major = element_line(colour = "black"),
  axis.text = element_text(color = "black", size = 10),
  axis.text.y = element_text(margin = margin(r = 8)) # 调整y轴刻度与线条的距离
)

pc <- ggplot(data_of_weeds, 
            aes(x = "", y = Plantdensity, fill = Specie))+
  geom_bar(width = 0.8, stat="identity", color = "black") + # 缩小饼图宽度
  xlim(-1.2, 1.2) + # 扩大x轴范围，预留空间
  coord_polar("y", start = 0) + 
  facet_grid(.~ Cluster, labeller = as_labeller(tickname))

pc1 <- pc + tema_piechart + 
  theme(strip.background.x = element_rect(fill="white"),
        strip.text.x = element_text(vjust = 2, margin = margin(b = 10))) # 调整面板标签位置

内容的提问来源于stack exchange，提问作者Claudio Russo