Summary

You can now use RStudio to write and run a small R script, and find help when a command is unfamiliar.

What you learned

  • R is the language that performs the calculations. RStudio provides an interface for writing code, running it, inspecting objects, and viewing plots.
  • The Console runs commands immediately. A script saves commands as a text file so that you can run them again.
  • The Environment pane shows objects in the current R session. The Files, Plots, Packages, and Help tabs support different tasks; their positions depend on your RStudio layout.
  • Use <- to assign a value to an object. Object names are case sensitive: height and Height are different names.
  • Functions take arguments in parentheses. Comments start with # and explain the code without being executed.

A short recap in R

Run these lines from a saved script. In RStudio, use Ctrl+Enter on Windows/Linux or Cmd+Enter on macOS to send a line or selection to the Console.

# Illustrative measurements in centimeters
height <- 12
width <- 5
area <- height * width
area
sqrt(area)

area is 60; sqrt(area) is approximately 7.746. Assignment stores a result, while entering an object’s name prints its value. Parentheses control the order of calculations, for example (2 + 3) * 4 gives 20.

Finding help

For a known function, enter ?sqrt or help("sqrt"). For a topic whose function name you do not know, try help.search("square root") and inspect the results. Check the relevant parts of a help page:

Section What it tells you
Title and Description What the function does.
Usage How to call it and which arguments have defaults.
Arguments What each input means and which values it accepts.
Value What the function returns.
Examples Calls you can run and adapt.

When a command fails, read the error message, check spelling and parentheses, and reduce the problem to a few reproducible lines. Include those lines and the exact error when asking for help.

Check your understanding

  1. Explain the difference between typing a command in the Console and saving it in a script.
  2. Change width to 8. Which lines must you rerun to update area and its square root?
  3. Find the Arguments and Value sections of ?sqrt. What input does it expect, and what does it return?

Revisit first steps and reading help files if needed.

Test GUI

Updated: