The central component of everything we will be doing in R this semester is data. Even non-data science programs revolve around data. At a very basic level, a computer is just a fancy calculator that takes in numbers and spits out an answer. To a computer, even things like words and pictures are stored internally as numbers.
R can handle many types of data. For example, one type of data is a number. Let’s start by
When you open RStudio, you will notice that the program is divided up into 3 or 4 panes. On the left, you should see a pane called Console. You can type programming language expressions into the Console after the
> symbol, hit enter, and the expression will be evaluated.
Try entering a number after the
> in the Console (e.g. 2), then Enter, and see what happens.
When you hit enter, the R interpreter reads in the line, evaluates it, and returns the answer. In this case, you entered 2, so the computer thinks “Hey, it’s a 2! Wow, a two! The result of 2 is… drum roll, please… 2!” and you get a two.
Cool! But not, I confess, particularly useful. Let’s fix that: next we’ll add two numbers together. At the prompt, enter two numbers separated by a plus sign, +
> 2 + 2
What do you get?
The plus sign,
+, is called an operator. As you might expect, it is the addition operator. There are many other operators in R. Here are a few of the more useful ones. See if you can figure out what they do:
Enter each of these at the prompt, with a number on each side, and see what you get, e.g.
> 3 ** 2
> 5 == 5