To make a histogram (Figure 2.8), use
hist() and pass it a vector of values:
hist(mtcars$mpg) # Specify approximate number of bins with breaks hist(mtcars$mpg, breaks = 10)
With the ggplot2, you can get a similar result using
geom_histogram() (Figure 2.9):
library(ggplot2) ggplot(mtcars, aes(x = mpg)) + geom_histogram() #> `stat_bin()` using `bins = 30`. Pick better value with `binwidth`. # With wider bins ggplot(mtcars, aes(x = mpg)) + geom_histogram(binwidth = 4)
When you create a histogram without specifying the bin width,
ggplot() prints out a message telling you that it’s defaulting to 30 bins, and to pick a better bin width. This is because it’s important to explore your data using different bin widths; the default of 30 may or may not show you something useful about your data.