使用散点图和折线图向 ggplot 添加图例

Question

我在一张图上混合了散点图和折线图 ggplot。散点图和折线图基于不同的数据。点是蓝色的，线是红色的。我想添加一个图例，显示与数据对应的蓝点和与红线中的数据对应的红线。这在 ggplot 中可行吗？

我的数据是JetFuelHedging.csv来自Introduction to Quantitative Finance in R in R，可以找到here

price <- read.csv("JetFuelHedging.csv")

price$Date <- as.Date(as.yearmon(price$Date))

ggplot(price, aes(x=Date, group = 1))+
  geom_point(aes(y = JetFuel), colour = "dodgerblue2")+
  geom_line(aes(y=HeatingOil), color = "Red")+
  labs(x = "Month", y = "USD")+
  scale_x_date(date_breaks = "6 months", date_labels =  "%b %Y")+
  theme(axis.text.x=element_text(angle=60, hjust=1))

Answer 1

要获得传奇，您应该在 aes() 中包含 colour。

试试这个-

> price$Date <- as.Date(as.yearmon(price$Date))

> ggplot(price, aes(x=Date, group = 1))+
  geom_point(aes(y = JetFuel, colour = "dodgerblue2"),show.legend = T)+
  geom_line(aes(y=HeatingOil, colour = "Red"),show.legend = T)+
  labs(x = "Month", y = "USD")+
  scale_x_date(date_breaks = "6 months", date_labels =  "%b %Y")+
  theme(axis.text.x=element_text(angle=60, hjust=1)) + 
  scale_colour_manual(name = 'Legend', 
                      guide = 'legend',
                      values = c('dodgerblue2' = 'blue',
                                 'Red' = 'red'), 
                      labels = c('Points',
                                 'Line'))

编辑Legend Shapes可以参考这个-

ggplot2 custom legend shapes

使用散点图和折线图向 ggplot 添加图例

Adding a legend to a ggplot with a scatterplot and a line graph

plot

r

ggplot2

quantitative-finance