Plotting data using ggplot

Question

I am trying to plot my data with legends for the black line as well but I don't know how it can be done so that "MYLINE" will appear on the right side under MY2? and how to control the colour and properties of this line e.g colour, thickness,...?

MY1_DIS_REF$METHOD <- "MY1"
MY1_plot<-MY1_DIS_REF[,-c(5,6,7)]
MY2_DIS_REF$METHOD <- "MY2"
MY2_plot<-MY2_DIS_REF[,-c(5,6,7)]
MY1andMY2_PLOT <- rbind(MY1_plot,MY2_plot)

ggplot()+
  geom_point(data=MY1andMY2_PLOT,aes(X,Y,color=METHOD),alpha=0.5)+
  geom_path(data=line,aes(V1,V2,group=B1,),size=1)+
  xlab("X")+
  ylab("Y")+
  facet_wrap(~B1,scales = "free")+
  theme_bw()+coord_flip()

Answer 1

If you also want to rename the legend, you can do the following:

ggplot()+
  geom_point(data=MY1andMY2_PLOT,aes(X,Y,color=METHOD),alpha=0.5)+
  geom_path(data=line,aes(V1,V2, group = B1, linetype = "MyLine"), size=3, colour = "blue") +
  labs(x = "X", y = "Y", linetype = "DESIRED_LINETYPE_NAME", color = "DESIRED_COLOR_NAME")+
  facet_wrap(~B1,scales = "free")+
  theme_bw()+coord_flip()

Answer 2

You can add a separate legend for the line by using a different aesthetic to the one the current legend is using:

ggplot()+
  geom_point(data=MY1andMY2_PLOT,aes(X,Y,color=METHOD),alpha=0.5)+
  geom_path(data=line,aes(V1,V2, group=B1, linetype = "Myline"), size=1)+
  xlab("X")+
  ylab("Y")+
  facet_wrap(~B1,scales = "free")+
  theme_bw()+coord_flip()

You can change the other aesthetics with arguments outside of aesthetics, e.g. thickness is controlled by size:

ggplot()+
  geom_point(data=MY1andMY2_PLOT,aes(X,Y,color=METHOD),alpha=0.5)+
  geom_path(data=line,aes(V1,V2, group=B1, linetype = "Myline"), size=3)+
  xlab("X")+
  ylab("Y")+
  facet_wrap(~B1,scales = "free")+
  theme_bw()+coord_flip()

You can change colors by editing the color scale (red and blue are default):

ggplot()+
  geom_point(data=MY1andMY2_PLOT,aes(X,Y,color=METHOD),alpha=0.5)+
  geom_path(data=line,aes(V1,V2, group=B1, linetype = "Myline"), size=1)+
  xlab("X")+
  ylab("Y")+
  facet_wrap(~B1,scales = "free")+
  theme_bw()+coord_flip() +
  scale_color_manual(values = c("orange", "pink"))

Edit: Change line colour:

ggplot()+
  geom_point(data=MY1andMY2_PLOT,aes(X,Y,color=METHOD),alpha=0.5)+
  geom_path(data=line,aes(V1,V2, group=B1, linetype = "Myline"), size=3, colour = "blue") +
  xlab("X")+
  ylab("Y")+
  facet_wrap(~B1,scales = "free")+
  theme_bw()+coord_flip()