CODEWITHSUNDEEP
rggplot2
AndyDudley
AndyDudley

Reputation: 51

Display ggplot legend correctly for line/shape combinations

I am trying to create a plot for three groups using three different coloured lines but only two of the groups have point markers. I can get the plot to display correctly but the legend shows the same point markers for all three groups.

I have created a reproducible example using the mpg dataset

library(tidyverse)

ggplot(mpg) +
  geom_line(mapping = aes(x = displ, y = cty, color = drv), size = 1) +
  geom_point(data = subset(mpg, drv != '4'), mapping = aes(x = displ, y = cty, color = drv, shape = drv), size = 3) +
  scale_color_manual(name="Variable", labels = c("4", "f", "r"), values=c("4" = "#DA2128", "f" = "black", "r" = "blue"))  +
  scale_shape_manual(name="Variable", labels = c("f", "r"), values = c("f" = 16, "r" = 17), guide = FALSE)

The group '4' should have no point marker in the legend and the group 'r' should show a triangle marker

enter image description here

Thanks in advance for your help

Upvotes: 1

Views: 1511

Answers (3)

Roman
Roman

Reputation: 17648

Try some alpha

ggplot(mpg, aes(x = displ, y = cty, color = drv, shape = drv)) +
  geom_line() +
  geom_point(aes(alpha=drv), size = 3) + 
  scale_alpha_manual(values = c(0,1,1)) +
  scale_shape_manual(values = c(1,16, 17))

enter image description here

Or simply set shape 4 to NA

ggplot(mpg, aes(x = displ, y = cty, color = drv, shape = drv)) +
  geom_line() +
  geom_point(size = 3) + 
  scale_shape_manual(values = c(NA, 16, 17)) +
  scale_color_manual(values = c("#DA2128", "black", "blue"))

enter image description here

Upvotes: 1

Simon
Simon

Reputation: 602

You could also disable the legend for shape and set the values for shape manually in the color legend: ggplot(mpg) + geom_line(mapping = aes(x = displ, y = cty, color = drv), size = 1) + geom_point(data = subset(mpg, drv != '4'), mapping = aes(x = displ, y = cty, color = drv, shape = drv), size = 3) + scale_color_manual(name="Variable", labels = c("4", "f", "r"), values=c("4" = "#DA2128", "f" = "black", "r" = "blue"), guide=guide_legend(override.aes = list(shape = c("4" = NA, "f" = 16, "r" = 17)))) + scale_shape_manual(values = c("f" = 16, "r" = 17), guide=F) enter image description here

Upvotes: 0

Edu
Edu

Reputation: 903

Adding linetype argument in your geom_line() with the variable of interest (drv in this case) gives your expected result.

library(tidyverse)

ggplot(mpg) +
  geom_line(mapping = aes(x = displ, y = cty, color = drv, linetype = drv), size = 1) +
  geom_point(data = subset(mpg, drv != '4'), mapping = aes(x = displ, y = cty, color = drv, shape = drv), size = 3) +
  scale_color_manual(name="Variable", labels = c("4", "f", "r"), values=c("4" = "#DA2128", "f" = "black", "r" = "blue"))  +
  scale_shape_manual(name="Variable", labels = c("f", "r"), values = c("f" = 16, "r" = 17), guide = FALSE)

enter image description here

Upvotes: 0

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