Ggplot2: Can't change order of guides when plotted together


#1

Hia, hopefully simple question:

I'd like to draw some lines over some points, but have a combined legend with the points shown over the lines. I get the desired legend if I draw the lines first, but I can only get the desired graph if I draw the points first. Tweaking the order of the guides seems like the way to go, but ends up showing two separate guides instead of one. Example below.

Can I force the guides to be plotted together?
Thanks,
Andrew

library(ggplot2)

n = 10
df <- data.frame(x = rep(1:n, 2),
                 y = c(1:n, n:1),
                 group = c(rep("a", n), 
                           rep("b", n)))

# Desired legend, incorrect graph
ggplot(df, aes(x, y, linetype = group)) +
  geom_smooth(method = "lm", se = F,
              size = 1.5, color = "black") +
  geom_point(aes(color = group), size = 5) +
  guides(linetype = guide_legend(keywidth = 5))

# Desired graph, incorrect legend
ggplot(df, aes(x, y, linetype = group)) +
  geom_point(aes(color = group), size = 5) +
  geom_smooth(method = "lm", se = F,
              size = 1.5, color = "black") +
  guides(colour = guide_legend(keywidth = 5))

# Changing guide order doesn't help.
ggplot(df, aes(x, y, linetype = group)) +
  geom_point(aes(color = group), size = 5) +
  geom_smooth(method = "lm", se = F,
              size = 1.5, color = "black") +
  guides(colour = guide_legend(keywidth = 5, order = 1),
         linetype = guide_legend(keywidth = 5, order = 2))

#2

Sorry, I don't actually know how to do what you're describing, I'm just adding a reprex so we have input and output (makes it easier to see what you're describing):

library(ggplot2)

n = 10
df <- data.frame(x = rep(1:n, 2),
                 y = c(1:n, n:1),
                 group = c(rep("a", n), 
                           rep("b", n)))

# Desired legend, incorrect graph
ggplot(df, aes(x, y, linetype = group)) +
  geom_smooth(method = "lm", se = F,
              size = 1.5, color = "black") +
  geom_point(aes(color = group), size = 5) +
  guides(linetype = guide_legend(keywidth = 5))


# Desired graph, incorrect legend
ggplot(df, aes(x, y, linetype = group)) +
  geom_point(aes(color = group), size = 5) +
  geom_smooth(method = "lm", se = F,
              size = 1.5, color = "black") +
  guides(colour = guide_legend(keywidth = 5))


# Changing guide order doesn't help.
ggplot(df, aes(x, y, linetype = group)) +
  geom_point(aes(color = group), size = 5) +
  geom_smooth(method = "lm", se = F,
              size = 1.5, color = "black") +
  guides(colour = guide_legend(keywidth = 5, order = 1),
         linetype = guide_legend(keywidth = 5, order = 2))

Created on 2018-06-30 by the reprex package (v0.2.0).