我想在R中创建一个双层饼图/圆环图

# 安装并加载必要的包
install.packages("ggplot2")
library(ggplot2)

# 创建示例数据
data <- data.frame(
  Category = c("A", "B", "C", "D"),
  SubCategory = c("A1", "A2", "B1", "C1"),
  Value = c(30, 20, 15, 35)
)

# 计算内层和外层的值
data$InnerValue <- data$Value * 0.7  # 内层值
data$OuterValue <- data$Value * 0.3  # 外层值

# 创建双层饼图
ggplot(data, aes(x = "", y = Value, fill = Category)) +
  geom_bar(stat = "identity", width = 1) +
  coord_polar("y", start = 0) +
  geom_bar(aes(y = InnerValue, fill = SubCategory), stat = "identity", width = 0.7, position = position_nudge(y = -0.15)) +
  coord_polar("y", start = 0) +
  theme_void() +
  scale_fill_manual(values = c("red", "blue", "green", "purple", "orange", "brown")) +
  labs(title = "双层饼图示例")