CODEWITHSUNDEEP
rggplot2
Dekike
Dekike

Reputation: 1284

Why a second legend is not being included in my ggplot?

The plot below is to create a ggplot in which I show the relationship between two variables according to the raw data (points) and according to two different models (m1 and m3), from which I extract the coefficients and I drow two continuous lines. The grey line is just to show a relationship of 1:1.

enter image description here

line_colors <- RColorBrewer::brewer.pal(7, "Reds")[c(2,4,6)]
line_colors

Plot_a <- ggplot(Todo.6min, aes(x=VeDBA.V13AP, y=VeDBA.X16, colour=ID)) + 
  geom_point(size=1.5,alpha=0.2) +
  geom_abline(aes(slope=1,intercept=0),linetype="dashed",color="grey52",size=1.5) +
  theme_bw() + 
  theme(strip.background=element_blank(),
        axis.title.x =element_blank(),
        axis.title.y =element_blank(),
        axis.text.x = element_text(angle = 0, hjust = 0.5,size = 15),
        axis.text.y = element_text(angle = 0, hjust = 0.5,size = 15),
        axis.line = element_line(),
        panel.grid.major= element_blank(),
        panel.grid.minor = element_blank(),
        legend.position = "right",
        legend.text=element_text(size=18),
        legend.title = element_text(size=19, face = "bold"),
        legend.key=element_blank(),
        panel.border = element_blank(),
        strip.placement = "outside") +
  guides(color=guide_legend(override.aes=list(fill=NA)))

Plot_a

Plot_b <- Plot_a +
  geom_abline(aes(linetype = "m1"),slope = fixef(mod2b)[2] , intercept = fixef(mod2b)[1], color = line_colors[1], size=1.5) +
  geom_abline(aes(linetype = "m3"),slope = fixef(mod2d)[2] + fixef(mod2d)[3], intercept = fixef(mod2d)[1], color = line_colors[2], size=1.5) + 
  scale_linetype_manual(values = c(m1 = "solid", m3 = "solid"),labels = c(m1 = "m1", m3 = "m3")) +
  labs(color = "ID", linetype = expression(Model)) +
  guides(linetype = guide_legend(override.aes = list(color = line_colors)))
         
Plot_b

My doubt is why I do not get a legend for the continuous lines although I used scale_linetype_manual for indicating that I wanted a legend in which appears "m1" and "m3" as legend.text.

Does anyone know where is the mistake?

Upvotes: 1

Views: 507

Answers (1)

teunbrand
teunbrand

Reputation: 37943

My suggestion would be to manually populate the mapping of geom_abline(), and then cut the data so that it matches the number of lines you're drawing. Illustrated below with an inbuilt dataset.

library(ggplot2)

ggplot(iris, aes(Sepal.Width, Sepal.Length)) +
  geom_abline(aes(linetype = c("m1", "m3"),
                  slope = c(0.5, 0.75),
                  intercept = c(0, 0.5)),
              data = iris[1:2,])

Created on 2020-11-06 by the reprex package (v0.3.0)

For your use case you'd have to substute slope = c(0.5, 0.75) by slope = c(fixef(mod2b)[2], fixef(mod2d)[2]), etc.

Upvotes: 1

Related Questions