add a shape legend to ggplot R

Question

I have a ggplot and I want to add a legend to it, but it reflects only color and not the shape. I used scale_shape_manual, but it still does not work. Here is what I have

plot <- ggplot(data.frame(labels, yes.percent.avgs.gc, yes.percent.avgs.dp, yes.percent.avgs.gm)) +
  geom_point(aes(x=labels, y=yes.percent.avgs.gc, colour="GC"), shape=16, size=5) + # Plot individual points
  geom_point(aes(x=labels, y=yes.percent.avgs.dp, colour="DP"), shape=17, size=5) + # Plot individual points
  geom_point(aes(x=labels, y=yes.percent.avgs.gm, colour="GM"), shape=18, size=5) + # Plot individual points
  geom_smooth(data=data.frame(labels, pred.avgs), aes(x=labels, y=pred.avgs, colour="Prediction Scores"), fill=NA, method=lm, size=1) +
  xlab("Bin range") +
  ylab("Argument Score") +
  theme(legend.position = c(0.8, 0.2))+
  scale_shape_manual(name = "Legend",
                     labels = c("GC", "DP", "GM"),
                     values = c(16, 17, 18))

plot # show the plot

How can I get the legend to show both color and shape.

If you want automatic legend for shape, put `shape=` inside `aes()`. — tonytonov, Dec 25 '15 at 09:51

score 4 · Accepted Answer · edited May 23 '17 at 12:15

Apparently, the problem is that you are putting three geom_point layers on top of each other. This confuses ggplot which uses all shapes at once in legend.

The solution is to tidy your data before plotting it. Since you haven't provided reproducible example, I had to make it up.

library("ggplot2")
library("tidyr")
set.seed(123)
labels <- sample(c("L1","L2", "L3", "L4"), 12, replace = TRUE)
yes.percent.avgs.gc <- sample(1:100, 12)
yes.percent.avgs.dp <- sample(1:100, 12)
yes.percent.avgs.gm <- sample(1:100, 12)

tidy.df <- gather(data.frame(labels, 
                             yes.percent.avgs.gc, 
                             yes.percent.avgs.dp, 
                             yes.percent.avgs.gm),
                  group, value,
                  yes.percent.avgs.gc, yes.percent.avgs.dp, yes.percent.avgs.gm)

plot <- ggplot(tidy.df) + 
  geom_point(aes(x=labels, y=value, colour=group, shape=group), size=5) + 
  xlab("Bin range") +
  ylab("Argument Score") + 
  scale_shape_manual(name = "Legend",
                     labels = c("GC", "DP", "GM"),
                     values = c(16, 17, 18)) + 
  scale_colour_manual(name="Legend",
                      labels=c("GC", "DP", "GM"),
                      values=c("Red", "Green", "Blue"))
print(plot)

ggplot

I have dropped geom_smooth call, because I could not see any difference between plots with and without it.

This is just what I was looking for!. Thanks for the link to tidyr library. — AMisra, Dec 25 '15 at 18:27

add a shape legend to ggplot R

1 Answers1