Plotting yields over time
Now that the units have been dealt with, it's time to explore the datasets. An obvious question to ask about each crop is, "how do the yields change over time in each US state?" Let's draw a line plot to find out!
ggplot2 is loaded, and corn and wheat datasets are available with metric units.
This exercise is part of the course
Introduction to Writing Functions in R
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Using corn, plot yield (kg/ha) vs. year
___(___, ___(___, ___)) +
# Add a line layer, grouped by state
___(___(___ = ___)) +
# Add a smooth trend layer
___()