smaller <- diamonds %>%
 filter(carat < 3)
ggplot(data = smaller, mapping = aes(x = carat, y = price)) +
 geom_boxplot(mapping = aes(group = cut_number(carat, 20)))

ggplot(data = smaller, mapping = aes(x = carat, y = price)) +
 geom_boxplot(mapping = aes(group = cut_width(carat, 0.1)))