Topic 3 Introduction to R and R Studio
3.1 By the end of this section, you should be able to:
- Download R and R studio
- Identify the R script, R console, Data environment and file browser in R studio
- Write and run R code from a script
- Install and load R packages
3.2 Why learn / use R?
3.2.1 Some information about R
- R is developed and used by scientists and researchers around the world
- Open source = no cost
- Constant development
- Connects to other data science/research tools
- Worldwide community: training widely available
- Encourages transparency and reproducibility
- Publication-ready outputs
3.2.2 Moving from other software to R
- Workflow is different
- Organise files and data differently
- Workspace can contain data and outputs
- Can manage multiple datasets within a workspace
- Learning curve can be steep initially
- e.g. Variables and coding, scripts
- Need to know what you want
- e.g. building your regression model / ANOVA error terms
3.3 R has many advantages
- Using scripts means analysis is easy to follow and reproduce
- R scripts are small, online collaboration, no SPSS “older version” problems
- Data can be organised and reorganised however you need it (tidyr)
- Packages are available for “cutting edge” analysis: e.g. Big Data & Machine Learning
- A robust language for precise plots and graphics (ggplot)
- R analysis code can be embdeded into documents and presentations (R Markdown)
3.5 The R Studio environment
The interface for R Studio looks daunting at first. However, there are 4 main sections, 2 on the left and 2 on the right.
- MAIN TOP: R Script files or R Document Files
- Where we usually type our code as a script before we run it. Script files are usually saved so we can work on them and rerun the code again later (.R files).
- MAIN BOTTOM: Console
- Shows the output of our R code. We can type R code directly into the console and the answer will ouput immediately. However, it is more convenient to use script files.
- RIGHT TOP: Environment
- Contains all of the objects (e.g. data, analysis, equations, plots) that are currently stored in memory. We can save all of this to a file and load it later (.RData files).
- RIGHT BOTTOM: File Browser
- The folder that R is working from is called ‘the working directory’ and it will automatically look for files there if we try to import something (e.g. a data file). Using the more button on the file browser allows you to set your desired working directory.
3.6 Working with a script
Scripts can be opened from the File menu.
![](images/file.png)
Creating a new script
The purpose of scripts is to allow you to type your analysis code and save it for use later. Scripts include, for example:
- Code for importing data into R
- Your analysis code (e.g. t-test or descriptive statistics)
- Code for graphs and tables
- Comments and notes (preceded by the ‘#’ symbol)
![](images/script.png)
Example of an R script
To run a script, you click the Run button. You can choose to:
- Run the whole script
- Run the selected line of code
![](images/run.png)
The run button
When you run the script, you will normally see output in the console.
![](images/console.png)
Output appears in the console
If your script contains code for a plot (graph), it will appear in the Plots window in the bottom right.
![](images/plotwindow.png)
Plots appear in the plot window
3.7 Installing and loading packages
install Packages from RStudio, Inc. on Vimeo.
Packages add functionality to R and allow us to do new types of analysis.
They can be installed via the menu (Tools -> Install Packages)
The can also be installed using code:
install.packages()
For example, TidyR is a package that contains functions for sorting and organising data. To install the package:
![](images/installPackages.png)
Installing a package in RStudio
or use the code:
install.packages(“tidyr”)
Once a package is has been installed, you need tp load it using the library() command. For example:
library(“tidyr”)