Wrangling geom_bar

Whereas geom_col() expects you to pass it a y-axis mapping column, geom_bar() doesn't take a y-axis call (at least by default).

Instead, geom_bar() takes your x-axis mapping and counts every single observation (or row of the passed dataframe) for each class and then draws bars of corresponding heights

These two code chunks will give you the same plot:

# geom_col()
data %>%
  groupby(xAxisCol) %>%
  summarize(value = n()) %>%
  ggplot(aes(x = xAxisCol, y = value) + 
  geom_col()

# geom_bar()
data %>%
  ggplot(aes(x = xAxisCol)) +
  geom_bar()

Let's use geom_bar() to make a look at observations with a large number of cases by region our WHO data.

filter() the who_disease data into only observations (rows) with greater than 1000 cases.
Map the x-axis to the region column.
Add geom_bar() to the plot object to draw the bars.

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Exercise

Wrangling geom_bar

Instructions