如何在ggplot中注释条形图上的某个点？

library(ggplot2)

# 创建数据框
data <- data.frame(category = c("A", "B", "C", "D"),
                   value = c(10, 20, 15, 25))

# 创建基础图形
p <- ggplot(data, aes(x = category, y = value))

# 创建条形图
p <- p + geom_bar(stat = "identity")

# 添加文本标签
p <- p + geom_text(aes(label = value), vjust = -0.5)

# 设置图形样式
p <- p + theme(plot.title = element_text(hjust = 0.5),
               axis.title.x = element_blank(),
               axis.title.y = element_blank())

# 显示图形
print(p)