There are many packages to draw maps in R. Personally, I prefer to use leaflet and ggplot2. leaflet is a web application so that we can explore data interactively, and ggplot2 can merge data conveniently.
Some one write their code causually which leads to the difficulties to read. And it may be inevitable to be lazy in programming and not paying attention to code specifications. That will cause some inconvenience to no matter others read our code or ourselves check our own work.
This website is established by R Blogdown. So the first article here is to introduce how to build it by R Blogdown.