• Donald Knuth, 1983

The key idea here is very simple; if you want to trust your results you should: - be able to document your manipulation in plain English - Recreate your entire analysis from start to finish from scratch

You’ll notice of course at this point that the course assignments app is just using R Markdown documents to compile and send me your solutions!

I’ve already installed ggplot2 for you, but if you were working on your own computer you could install it by running:

# note quotes
install.packages("ggplot2")

The other way to access functions in packages, which you’ve seen using the course app is with the :: operator:

ggplot2::ggplot()

Packages come with (possibly) three things:

• New functions that you can run
• Documentation for each function and sometimes higher level tutorials called ‘vignettes’ and ‘demos’
• Data sets; usually the data needed to run examples

Let’s open the main help page for ggplot2:

?ggplot2