Get legend from different data frames

[Miguel_V]

Hi, this is my first post. I've been looking for answers here and there but i can´t solve this:

I have some data that is plotted with ggplot as dots. Then i created a data frame that contains the values of a line that i need to plot in the previous plot. It works well with my code but i cant see the name of the line in the legend box. Thanks in advance.

t <- -40:10
z <- (8*t)+10
df3 = data.frame(t, z)
names(df3) <- c("t", "z")
df3$lin <- c("lin")

sp3<-ggplot(Datos, aes(x=O18, y=H2, color=Lugar)) +
  geom_point(shape = 21, size=1)+xlim(-50, 20)+ylim(-350, 100)+geom_line(data=df3, aes(x=t, y = z), color= "red")
sp3+labs(x = expression(paste(delta^{18}, "O (\u2030)"[VSMOW])), y = expression(paste(delta^{2}, "H (\u2030)"[VSMOW])))+
  theme_bw()+
  scale_color_brewer(palette = "Set1")+
  theme(legend.position = c(0.8, 0.2), legend.title = element_blank(),panel.border = element_rect(colour = "black", fill=NA), legend.box.background = element_rect(colour = "black"))+
  guides(color = guide_legend(override.aes = list(size = 3)))

[andresrcs]

Hi!

To help us help you, could you please turn this into a proper reproducible example (reprex) illustrating your issue? Please have a look at this guide, to see how to create one:

FAQ: How to do a minimal reproducible example ( reprex ) for beginners

A minimal reproducible example consists of the following items: A minimal dataset, necessary to reproduce the issue The minimal runnable code necessary to reproduce the issue, which can be run on the given dataset, and including the necessary information on the used packages. Let's quickly go over each one of these with examples: Minimal Dataset (Sample Data) You need to provide a data frame that is small enough to be (reasonably) pasted on a post, but big enough to reproduce your issue. Let's say, as an example, that you are working with the iris data frame head(iris) #> Sepal.Length Sepal.Width Petal.Length Petal.Width Species #> 1 5.1 3.5 1.4 0.…

[Dobrokhotov1989]

I think the problem is that for geom_line() you defined color not inside of aes(), hence there is no mapping for the line in legend. If you add color = lin it probably would work.

t <- -40:10
z <- (8*t)+10
df3 = data.frame(t, z)
names(df3) <- c("t", "z")
df3$lin <- c("lin")

sp3<-ggplot(Datos, aes(x=O18, y=H2, color=Lugar)) +
  geom_point(shape = 21, size=1)+xlim(-50, 20)+ylim(-350, 100)+geom_line(data=df3, aes(x=t, y = z, color = lin))
sp3+labs(x = expression(paste(delta^{18}, "O (\u2030)"[VSMOW])), y = expression(paste(delta^{2}, "H (\u2030)"[VSMOW])))+
  theme_bw()+
  scale_color_brewer(palette = "Set1")+
  theme(legend.position = c(0.8, 0.2), legend.title = element_blank(),panel.border = element_rect(colour = "black", fill=NA), legend.box.background = element_rect(colour = "black"))+
  guides(color = guide_legend(override.aes = list(size = 3)))