Getting started using R

Pedro Cardoso-Leite

How to use R?

There are several options:

Binder

Binder

Installing R

Install R

Visit https://cloud.r-project.org/

You can find instructions to install R on your specific OS online.

Here for example.

Install R now!

The R console

Using R like a calculator

Example

>        # How can I help?
> 1 + 2  # Press Enter: I want to know the answer
         # Please evaluate this expression
[1] 3    # Here's the result
>        # Anything else?

Try it out!

  • 12 / 5.5
  • 2 > 1
  • (5-2) <= (8 %% 3)
  • 2^5
  • sqrt(9)
  • log2(32)

Key concepts

Example 1:

log2(32)

Example 2:

1 + 2

What are these symbols? Are there different kinds of things?

Code is text

age <- c(18, 23, 43)
mean_age <- mean(age)
print(paste0("The mean age is ", round(mean_age, 1), " years."))

What is RStudio?

Install RStudio!

https://posit.co/download/rstudio-desktop/

IDE: Integrated development environments

The R GUI is bare bones.

Programmers use IDEs to work effectively.

IDEs provide tons of features that make programming easier and more fun.

RStudio

https://docs.posit.co/ide/user/ide/guide/ui/images/rstudio-panes-labeled.jpeg

Some key benefits of RStudio

  • see and work on more files at the same time
  • see the current state of your environment
  • inspect data
  • code completion, syntax highlighting
  • help
  • package management
  • data import wizzard
  • …and much more.

Packages

Install packages

Packages offer you additional functionality (functions, code, data not included in base R).

You will almost always use additional packages, but depending on your specific needs you might use different ones.

To use a package involves two simple steps:

Step 1: download the package

This is done only once (but you may need to redownload if there is a newer version of package).

To download a package, you need to “install” the package (e.g., using install.packages("package_name"))

Step 2: load the package

A package is not automatically available; you need to activate it before you can use it.

To activate a package, first you must have installed it. Second you need to call library("package_name").


Beginners often mix this up this two steps.

You can do those steps either using code (e.g., typed in the console) or by using RStudio package panel.

Example: installing the “swirl” package (using code)

Step 1:

In the console type

install.packages("swirl")

“swirl” is the name of the package we want to download on our computer.

This command will download the code from that package from CRAN and put in on your computer.

Example: installing the “swirl” package (using code)

Step 2:

Each time you want to use that package, you need to load it into R.

In the console, type:

library("swirl")

Now the code from the swirl package is aviable for use.

Exercise: Install the ggplot2 package

Exercise: Install the tidyverse package

Tidyvserse

Tidyverse is a set of well-designed packaged that work very well together to effectively accomplish 90% of the data science tasks.

Conclusion

We’ve installed R and RStudio and we’ve seen how to install packages.

We are now ready to start programming.