绘图（使用图）

# Creates a 1 row - 2 columns format
par(mfrow=c(1,2))

plot(rnorm(100), main = "Graph 1", ylab = "Normal distribution")
grid()
legend(x = 40, y = -1, legend = "A legend")

plot(rnorm(100), main = "Graph 2", type = "l")
abline(v = 50)

结果： https://i.stack.imgur.com/UOTw4.jpg