在R中的同一条形图上绘制多个变量

install.packages("ggplot2")
library(ggplot2)

# 创建一个包含多个变量的数据集
data <- data.frame(
  category = c("A", "B", "C", "D"),
  variable1 = c(10, 15, 8, 12),
  variable2 = c(5, 7, 3, 9),
  variable3 = c(2, 4, 6, 8)
)

# 使用ggplot函数创建绘图对象，并指定数据集和x轴变量
p <- ggplot(data, aes(x = category))

# 使用geom_bar函数创建条形图，并指定不同的变量
p <- p + geom_bar(aes(y = variable1), stat = "identity", fill = "red", width = 0.2)
p <- p + geom_bar(aes(y = variable2), stat = "identity", fill = "blue", width = 0.2)
p <- p + geom_bar(aes(y = variable3), stat = "identity", fill = "green", width = 0.2)

# 添加图例和标签
p <- p + labs(title = "Multiple Variables Bar Plot", x = "Category", y = "Value")
p <- p + scale_fill_manual(values = c("red", "blue", "green"), 
                           labels = c("Variable 1", "Variable 2", "Variable 3"))

# 显示图形
print(p)