Zooming in

• If your goal is to zoom in on part of the plot, it is usually better to use the xlim() and ylim() arguments of coord_cartesian().
• when you truncate the scale limits, some data points will fall outside the boundaries you set, and ggplot2 has to make a decision about what to do with these data points. The default behavior in ggplot2 is to convert any data values outside the scale limits to NA.