如何用R绘制可读分组环形图？解决现有绘图不可辨识问题

我用R代码制作分组环形图，但生成的图表完全无法辨识，数据为多分组带数值的结构，代码如下：

# library
library(tidyverse)

# load your data (from files)
data <- read.csv("C:/Users/HP/Downloads/data.csv")

# 'empty bar' to add at the end of each group
empty_bar <- 3
to_add <- data.frame( matrix(NA, empty_bar*nlevels(data$topic), ncol(data)) )
colnames(to_add) <- colnames(data)
to_add$topic <- rep(levels(data$topic), each=empty_bar)
data <- rbind(data, to_add)
data <- data %>% arrange(topic)
data$id <- seq(1, nrow(data))

# name and the y position of each label
label_data <- data
number_of_bar <- nrow(label_data)
angle <- 90 - 360 * (label_data$id-0.5) /number_of_bar     # I substract 0.5 because the letter must have the angle of the center of the bars. Not extreme right(1) or extreme left (0)
label_data$hjust <- ifelse( angle < -90, 1, 0)
label_data$angle <- ifelse(angle < -90, angle+180, angle)

# prepare a data frame for base lines
base_data <- data %>% 
  group_by(topic) %>% 
  summarize(start=min(id), end=max(id) - empty_bar) %>% 
  rowwise() %>% 
  mutate(title=mean(c(start, end)))

# prepare a data frame for grid (scales)
grid_data <- base_data
grid_data$end <- grid_data$end[ c( nrow(grid_data), 1:nrow(grid_data)-1)] + 1
grid_data$start <- grid_data$start - 1
grid_data <- grid_data[-1,]

# Make the plot
p <- ggplot(data, aes(x=as.factor(id), y=value, fill=topic)) +
  geom_bar(aes(x=as.factor(id), y=value, fill=topic), stat="identity", alpha=0.5) +
  
  # Add a val=100/75/50/25 lines. I do it at the beginning to make sur barplots are OVER it.
  geom_segment(data=grid_data, aes(x = end, y = 80, xend = start, yend = 80), colour = "grey", alpha=1, size=0.3 , inherit.aes = FALSE ) +
  geom_segment(data=grid_data, aes(x = end, y = 60, xend = start, yend = 60), colour = "grey", alpha=1, size=0.3 , inherit.aes = FALSE ) +
  geom_segment(data=grid_data, aes(x = end, y = 40, xend = start, yend = 40), colour = "grey", alpha=1, size=0.3 , inherit.aes = FALSE ) +
  geom_segment(data=grid_data, aes(x = end, y = 20, xend = start, yend = 20), colour = "grey", alpha=1, size=0.3 , inherit.aes = FALSE ) +
  
  # Add text showing the value of each 100/75/50/25 lines
  annotate("text", x = rep(max(data$id),4), y = c(20, 40, 60, 80), label = c("20", "40", "60", "80") , color="grey", size=3 , angle=0, fontface="bold", hjust=1) +
  geom_bar(aes(x=as.factor(id), y=value, fill=topic), stat="identity", alpha=4) +
  ylim(-300,70000) +
  theme_minimal() +
  theme(
    legend.position = "none",
    axis.text = element_blank(),
    axis.title = element_blank(),
    panel.grid = element_blank(),
    plot.margin = unit(rep(-0.1, 5), "cm")) +
  coord_polar() + 
  geom_text(data=label_data, aes(x=id, y=value+10, label=tag, hjust=hjust), color="black", fontface="bold",alpha=0.6, size=2.5, angle= label_data$angle, inherit.aes = FALSE ) +
  # Add base line information
  geom_segment(data=base_data, aes(x = start, y = -5, xend = end, yend = -5), colour = "black", alpha=0.8, size=0.6 , inherit.aes = FALSE )  +
  geom_text(data=base_data, aes(x = title, y = -18, label=topic), hjust=c(1,1,1,0,0), colour = "black", alpha=0.8, size=4, fontface="bold", inherit.aes = FALSE)

p

生成的图表存在元素重叠、刻度与数据量级不匹配等问题，完全不可读，恳请提供优化方案。

1. 匹配刻度与数据量级 #

原代码刻度仅设置到80，但数据value值最高达数万，导致所有条形被拉伸重叠。根据数据范围重新设置刻度：

# 计算数据最大值，生成合理刻度
max_val <- max(data$value, na.rm = TRUE)
tick_vals <- seq(0, max_val, by = 10000)
# 生成刻度线段数据
grid_data <- base_data %>%
  rowwise() %>%
  mutate(ticks = list(tick_vals)) %>%
  unnest(ticks)

# 替换原刻度线段和标注代码
geom_segment(data=grid_data, aes(x = end, y = ticks, xend = start, yend = ticks), 
             colour = "grey", alpha=0.7, size=0.3 , inherit.aes = FALSE ) +
annotate("text", x = rep(max(data$id), length(tick_vals)), y = tick_vals, 
         label = as.character(tick_vals), color="grey", size=3 , angle=0, 
         fontface="bold", hjust=1)

2. 移除重复绘图元素 #

代码重复调用geom_bar，保留一次即可避免图层重叠：

# 仅保留一次条形图绘制
geom_bar(stat="identity", alpha=0.8) +

3. 优化标签显示 #

• 过滤空行标签（添加的empty_bar行无有效tag值）：

label_data <- data %>% filter(!is.na(tag))

• 动态调整标签偏移量，避免与条形重叠：

geom_text(data=label_data, aes(x=id, y=value + max_val*0.02, label=tag, hjust=hjust), 
          color="black", fontface="bold", alpha=0.8, size=2.5, 
          angle= label_data$angle, inherit.aes = FALSE )

4. 调整分组间距 #

若分组过多，减少empty_bar数量避免环形图过于松散：

empty_bar <- 1

完整优化后代码示例 #

library(tidyverse)

# 加载数据
data <- read.csv("C:/Users/HP/Downloads/data.csv")

# 调整分组空行数量
empty_bar <- 1
to_add <- data.frame( matrix(NA, empty_bar*nlevels(data$topic), ncol(data)) )
colnames(to_add) <- colnames(data)
to_add$topic <- rep(levels(data$topic), each=empty_bar)
data <- rbind(data, to_add)
data <- data %>% arrange(topic)
data$id <- seq(1, nrow(data))

# 准备标签数据，过滤空值
label_data <- data %>% filter(!is.na(tag))
number_of_bar <- nrow(label_data)
angle <- 90 - 360 * (label_data$id-0.5) /number_of_bar
label_data$hjust <- ifelse( angle < -90, 1, 0)
label_data$angle <- ifelse(angle < -90, angle+180, angle)

# 基线数据
base_data <- data %>% 
  group_by(topic) %>% 
  summarize(start=min(id), end=max(id) - empty_bar) %>% 
  rowwise() %>% 
  mutate(title=mean(c(start, end)))

# 刻度数据
max_val <- max(data$value, na.rm = TRUE)
tick_vals <- seq(0, max_val, by = 10000)
grid_data <- base_data %>%
  rowwise() %>%
  mutate(ticks = list(tick_vals)) %>%
  unnest(ticks)

# 绘图
p <- ggplot(data, aes(x=as.factor(id), y=value, fill=topic)) +
  # 刻度线
  geom_segment(data=grid_data, aes(x = end, y = ticks, xend = start, yend = ticks), 
               colour = "grey", alpha=0.7, size=0.3 , inherit.aes = FALSE ) +
  # 刻度标注
  annotate("text", x = rep(max(data$id), length(tick_vals)), y = tick_vals, 
           label = as.character(tick_vals), color="grey", size=3 , angle=0, 
           fontface="bold", hjust=1) +
  # 条形图
  geom_bar(stat="identity", alpha=0.8) +
  # y轴范围
  ylim(-max_val*0.1, max_val*1.1) +
  theme_minimal() +
  theme(
    legend.position = "bottom",
    axis.text = element_blank(),
    axis.title = element_blank(),
    panel.grid = element_blank(),
    plot.margin = unit(c(0.5,0.5,0.5,0.5), "cm")) +
  coord_polar() + 
  # 标签
  geom_text(data=label_data, aes(x=id, y=value + max_val*0.02, label=tag, hjust=hjust), 
            color="black", fontface="bold", alpha=0.8, size=2.5, 
            angle= label_data$angle, inherit.aes = FALSE ) +
  # 基线与分组标题
  geom_segment(data=base_data, aes(x = start, y = -max_val*0.05, xend = end, yend = -max_val*0.05), 
               colour = "black", alpha=0.8, size=0.6 , inherit.aes = FALSE )  +
  geom_text(data=base_data, aes(x = title, y = -max_val*0.08, label=topic), 
            hjust=ifelse(angle < -90, 1, 0), colour = "black", alpha=0.8, 
            size=4, fontface="bold", inherit.aes = FALSE)

p

内容的提问来源于stack exchange，提问作者tores