r - 使用 R 将图例添加到绘图中

Question

我使用 R 在一个图中创建了 4 条线。代码在这里

# Define 2 vectors
cars <- c(123.07, 110.51, 96.14, 98.71, 101.3)
trucks <- c(110.31, 89.91, 89.81, 89.31, 93.4, 95.81)
cars1 <- c(123.227, 110.221, 93.14, 98.22, 122.3)
trucks1 <- c(120.31, 89.91, 89.81, 89.31, 93.4, 95.81)
# Graph cars using a y axis that ranges from 0 to 12
plot(cars, type="o", col="blue", ylim=c(80,130))

# Graph trucks with red dashed line and square points
lines(trucks, type="o", pch=22, lty=2, col="red")
lines(cars1, type="o", col="yellow", ylim=c(80,130))

# Graph trucks with red dashed line and square points
lines(trucks1, type="o", pch=22, lty=2, col="green")
# Create a title with a red, bold/italic font
title(main="Autos", col.main="red", font.main=4)

我想知道如何为图中的每个图(线)添加图例。

谢谢

Answer 1

legend( "topleft", c("cars", "trucks", "cars1", "trucks1"), 
text.col=c("blue", "red", "yellow", "green") )

使用 ?legend 命令查看选项，例如图形上的其他位置，除了“左上角”或文本大小之外，是否在图例周围有一个框等。