显示y轴上的所有组，在R中以高位字符显示

# 创建一个示例数据集
data <- data.frame(
  group = c("A", "B", "C", "D", "E"), 
  value = c(10, 20, 15, 25, 30)
)

# 将group列转换为因子，并设置顺序
data$group <- factor(data$group, levels = unique(data$group))

# 绘制柱状图
barplot(data$value, names.arg = data$group, ylab = "Value", xlab = "Group", ylim = c(0, max(data$value)), col = "blue")

# 使用高位字符显示y轴标签
axis(side = 2, at = data$value, labels = as.character(data$value), las = 2)