4.8 Making a Proportional Stacked Area Graph

4.8.1 Problem

You want to make a stacked area graph with the overall height scaled to a constant value.

4.8.2 Solution

Use geom_area(position = "fill"), as in Figure 4.23, left:

ggplot(uspopage, aes(x = Year, y = Thousands, fill = AgeGroup)) +
  geom_area(position = "fill", colour = "black", size = .2, alpha = .4) +
  scale_fill_brewer(palette = "Blues")

4.8.3 Discussion

With position="fill", the y values will be scaled to go from 0 to 1. To print the labels as percentages, use scale_y_continuous(labels = scales::percent), as in Figure 4.23, right:

ggplot(uspopage, aes(x = Year, y = Thousands, fill = AgeGroup)) +
  geom_area(position = "fill", colour = "black", size = .2, alpha = .4) +
  scale_fill_brewer(palette = "Blues") +
  scale_y_continuous(labels = scales::percent)

Figure 4.23: A proportional stacked area graph

4.8.4 See Also

Creating stacked bar graph is done in a similar way. See Recipe 3.8 for information about computing the percentages separately.

For more on summarizing data by groups, see Recipe 15.17.