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.

10.1 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):

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

pg_plot

# Remove the legend for fill
pg_plot +
  guides(fill = FALSE)
Default appearance (left); With legend removed (right)
Figure 10-1. Default appearance (left); With legend removed (right)

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
pg_plot +
  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:

pg_plot +
  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 ...

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