11.19 Bar Chart Supplied Values


ds %>%
  count(wind_dir_9am) %>%
  ggplot(aes(x=wind_dir_9am, y=n)) +
  geom_col() +
  geom_text(aes(label=comma(n)), vjust=-0.2, size=3) +
  scale_y_continuous(labels=comma) +  
  labs(x=vnames["wind_dir_9am"], y="Count")

If the values of the bars are supplied in the source dataset (the y-axis) ggplot2::geom_col() is used. In this example we manually count the frequency of each wind direction in the dataset prior to invoking ggplot2::ggplot(). This modified dataset is then passed on to ggplot2::ggplot() to display. Of course, it would be better in this specific example to let ggplot2::geom_bar() do the work itself as in Section 11.21.

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