How to get geom_smooth() ignore my colour grouping

Question

I'm trying to make a plot with fitted lines for two levels of my factor(grouped by color). I used shapes to group another variant but when I try to fit smoother, I end up with 4 lines while I only need one two lines in total (1 per color)

Here is the data and code I use:

data <- structure(list(K = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("2s", "4s"), class = "factor"), 
    q = c(0.12, 0.11, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 
    0.03, 0.02, 0.01, 0.12, 0.11, 0.1, 0.09, 0.08, 0.07, 0.06, 
    0.05, 0.04, 0.03, 0.02, 0.01, 0.12, 0.11, 0.1, 0.09, 0.08, 
    0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, 0.12, 0.11, 0.1, 
    0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01), rarity = c(0.907, 
    0.9206, 0.9359, 0.9321, 0.9405, 0.9344, 0.9449, 0.9106, 0.8844, 
    0.8829, 0.8989, 0.798, 0.7464, 0.8225, 0.877, 0.8521, 0.9127, 
    0.9317, 0.9245, 0.9595, 0.9628, 0.9573, 0.9423, 0.9428, 0.5802, 
    0.6414, 0.5123, 0.57, 0.587, 0.5655, 0.5231, 0.517, 0.4694, 
    0.5459, 0.3745, 0.3274, 0.7936, 0.7821, 0.7297, 0.7227, 0.6814, 
    0.6608, 0.6721, 0.6202, 0.5924, 0.5659, 0.5448, 0.6138), 
    metric = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
    2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
    2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("APD", "ED"
    ), class = "factor")), .Names = c("K", "q", "rarity", "metric"
), class = "data.frame", row.names = c(NA, -48L))

library(ggplot2) 
ggplot(data=data, aes(x=q, y=rarity, colour=metric, shape=K))+ 
  ggtitle("Relationship")+
  xlab("rate of character change")+
  ylab("Correlation coefficient to average rarity")+
  geom_point()+
  geom_smooth(method=lm,se=FALSE)

Any advice on that?

Answer 1

You're getting two lines for each group becase it's being split by both metric and K. You really want the shape aesthetic to only apply to the point layer, not the smooth later. It's better just to move the aes() for that property there.

ggplot(data=data, aes(x=q, y=rarity, colour=metric))+ 
  ggtitle("Relationship")+
  xlab("rate of character change")+
  ylab("Correlation coefficient to average rarity")+
  geom_point(aes(shape=K))+
  geom_smooth(method=lm,se=FALSE)