如何用几个图层组在ggplot中画几条线？

library(ggplot2)

# 创建数据框
data <- data.frame(
  x = c(1, 2, 3, 4, 5),
  y1 = c(1, 2, 3, 4, 5),
  y2 = c(2, 4, 6, 8, 10),
  y3 = c(3, 6, 9, 12, 15)
)

# 创建基础图层
base_plot <- ggplot(data, aes(x = x))

# 添加第一条线
line1 <- base_plot + geom_line(aes(y = y1), color = "red")

# 添加第二条线
line2 <- line1 + geom_line(aes(y = y2), color = "blue")

# 添加第三条线
line3 <- line2 + geom_line(aes(y = y3), color = "green")

# 显示图形
print(line3)