Introduction

R is a language built specifically for statistics and data analysis, created by statisticians for other statisticians — that focus shows up everywhere, from how naturally it handles a column of numbers to the fact that its name is a play on its predecessor, S.

Running a script

An R file is saved with a .R extension and run from a terminal with Rscript, or line by line inside an interactive session like the R console or RStudio. Either way, print() writes a value out:

print("Hello, R!")

[1] "Hello, R!"

That [1] in front of the output isn't part of your string — it's R telling you this is the first element of whatever got printed. You'll see it constantly, and it matters a lot more once you start printing longer vectors, covered in the Vectors lesson.

Assignment is silent, bare expressions aren't

Assigning a value produces no output, but typing a bare expression — even in a script run with Rscript, not just interactively — automatically prints its result:

x <- 5
x
y <- 10
x + y

[1] 5
[1] 15

x <- 5 and y <- 10 produce nothing on their own. x alone and x + y alone are both bare expressions, so R prints whatever they evaluate to. This auto-printing rule is why so many R examples you'll see online never bother calling print() explicitly.