将图例添加到由多个不同数据帧构成的ggplot中

Question

I have the following code:

  year_2001_2003 <- df[(df[,"year"]==2001)|(df[,"year"]==2002) | (df[,"year"]==2003),]

  top_wmaxc <- year_2001_2003[year_2001_2003$w_maxc > quantile(year_2001_2003$w_maxc, 0.90), ]
  top_wmaxb <- year_2001_2003[year_2001_2003$w_maxb > quantile(year_2001_2003$w_maxb, 0.90), ]
  top_wmaxa <- year_2001_2003[year_2001_2003$w_maxa > quantile(year_2001_2003$w_maxa, 0.90), ]

  top_wminc <- year_2001_2003[year_2001_2003$w_minc > quantile(year_2001_2003$w_minc, 0.90), ]
  top_wminb <- year_2001_2003[year_2001_2003$w_minb > quantile(year_2001_2003$w_minb, 0.90), ]
  top_wmina <- year_2001_2003[year_2001_2003$w_mina > quantile(year_2001_2003$w_mina, 0.90), ]



  ggplot(year_2001_2003, aes(wkd_ind, assaults)) + geom_line( ) +
    geom_point(data=top_wmaxc, size = 4, color="yellow") +
    geom_point(data=top_wmaxb, size = 4, color="orange") + 
    geom_point(data=top_wmaxa, size = 4, color="red") +

    geom_point(data=top_wminc, size = 4, color="darkblue") +
    geom_point(data=top_wminb, size = 4, color="blue") + 
    geom_point(data=top_wmina, size = 4, color="lightblue") +

    facet_grid(.~year, scale="free") 

This produces the correct graph with the correct colors. However, I am not sure how to add a legend that captures these colors.

I have tried something like:

scale_colour_manual(values=c("yellow","orange","red", "darkblue", "blue", "lightblue"))

but it doesn't show up in the graph

Answer 1

I found a hack job way of doing this. Not sure if there's an easier way:

 ggplot(year_2001_2003, aes(wkd_ind, assaults)) + geom_line( ) +
    geom_point(data=top_wmaxc, size = 4, aes(color="p1")) +
    geom_point(data=top_wmaxb, size = 4, aes(color="p2")) + 
    geom_point(data=top_wmaxa, size = 4, aes(color="p3")) +

    geom_point(data=top_wminc, size = 4, aes(color="p4")) +
    geom_point(data=top_wminb, size = 4, aes(color="p5")) + 
    geom_point(data=top_wmina, size = 4, aes(color="p6")) +

    scale_colour_manual(name = "Line Color", 
          values=c(p1="yellow", p2="orange", p3="red", p4="purple", p5="blue", p6="lightblue")) + 

    facet_grid(.~year, scale="free")