Boxplots and density plots
The mileage of a car tends to be associated with the size of its engine (as measured by the number of cylinders). To explore the relationship between these two variables, you could stick to using histograms, but in this exercise you'll try your hand at two alternatives: the box plot and the density plot.
Deze oefening maakt deel uit van de cursus
Exploratory Data Analysis in R
Oefeninstructies
A quick look at unique(cars$ncyl) shows that there are more possible levels of ncyl than you might think. Here, restrict your attention to the most common levels.
- Filter
carsto include only cars with 4, 6, or 8 cylinders and save the result ascommon_cyl. The%in%operator may prove useful here. - Create side-by-side box plots of
city_mpgseparated out byncyl. - Create overlaid density plots of
city_mpgcolored byncyl.
Praktische interactieve oefening
Probeer deze oefening eens door deze voorbeeldcode in te vullen.
# Filter cars with 4, 6, 8 cylinders
common_cyl <- filter(___, ___)
# Create box plots of city mpg by ncyl
ggplot(___, aes(x = as.factor(___), y = ___)) +
geom_boxplot()
# Create overlaid density plots for same data
ggplot(common_cyl, aes(x = ___, fill = as.factor(___))) +
geom_density(alpha = .3)