Ggplot，如何在同一个图表中有两条线并让它产生一个图例

Question

以下是示例代码。它产生一个两折线图。但是，传说不会填充。我知道如何为图例添加代码。但是，在这种情况下，代码可以工作（不会产生错误），但不会出现图例。关于我缺少什么的任何想法？期望的结果将在底部显示 AvgFSize 及其对应的颜色以及 AvgHSize 及其对应的颜色。

 avgFSize1<-c(2,4,5,6,7,8,9,10,11)
 avgHSize1<-c(4,5,7,9,10,12,13,15,17)
 year1<-c(2010,2011,2012,2013,2014,2015,2016,2017,2018)
 singleh<-c(101,102,103,105,106,107,111,113,118)

 library(dplyr)
 library(ggplot2)


 testitem <- data.frame(avgFSize1, avgHSize1, year1, singleh)


chart26<-testitem%>%ggplot(aes(x=year1))+
geom_line(aes(y=avgHSize1), color = "black")+
geom_line(aes(y=avgFSize1), color = "red")+theme(legend.position="bottom", legend.box = 
"horizontal")+ggtitle("Average Household and Family Size")+
labs(y="AVerage Household and Family Size")

chart26

Answer 1

基本上你做了所有正确的事情，但忘记将color 移动到mapping = aes() 中。

testitem %>% ggplot(aes(x=year1))+
        geom_line(aes(y=avgHSize1, color = "black"))+
        geom_line(aes(y=avgFSize1, color = "red"))  +
        theme(legend.position="bottom", legend.box = "horizontal")+
        ggtitle("Average Household and Family Size")+
        labs(y="AVerage Household and Family Size") +
        scale_color_manual(
                labels = c("Household Size", "Family Size"),
                values = c("black", "red")
        )