R Graphics Cookbook

Chapter 10. Legends

Like the x- or y-axis, a legend is a guide: it shows people how to map visual (aesthetic) properties back to data values.

Removing the Legend

Problem

You want to remove the legend from a graph.

Solution

Use guides(), and specify the scale that should have its legend removed (Figure 10-1):

# The base plot (with legend)
p <- ggplot(PlantGrowth, aes(x=group, y=weight, fill=group)) + geom_boxplot()
p

# Remove the legend for fill
p + guides(fill=FALSE)

Figure 10-1. Left: default appearance; right: with legend removed

Discussion

Another way to remove a legend is to set guide=FALSE in the scale. This will result in the exact same output as the preceding code:

# Remove the legend for fill
p + scale_fill_discrete(guide=FALSE)

Yet another way to remove the legend is to use the theming system. If you have more than one aesthetic mapping with a legend (color and shape, for example), this will remove legends for all of them:

p + theme(legend.position="none")

Sometimes a legend is redundant, or it is supplied in another graph that will be displayed with the current one. In these cases, it can be useful to remove the legend from a graph.

In the example used here, the colors provide the same information that is on the x-axis, so the legend is unnecessary. Notice that with the legend removed, the area used for graphing the data is larger. If you want to achieve the same proportions in the graphing ...