Lecture 5

RStudio; R Basics

Byeong-Hak Choe

bchoe@geneseo.edu

SUNY Geneseo

September 6, 2024

Setting the DANL Tools

Setting the Tools

Posit Cloud

• Posit Cloud (formerly RStudio Cloud) is a web service that delivers a browser-based experience similar to RStudio, the standard IDE for the R language.

• For our course, we use Posit Cloud for the R programming component.

  • If you want to install R and RStudio on your laptop, you use my office hours.

Setting the Tools

RStudio Environment

• Script Pane is where you write R commands in a script file that you can save.
  • An R script is simply a text file containing R commands.
  • RStudio will color-code different elements of your code to make it easier to read.

Setting the Tools

RStudio Environment

• Console Pane allows you to interact directly with the R interpreter and type commands where R will immediately execute them.

Setting the Tools

RStudio Environment

• Environment Pane is where you can see the values of variables, data frames, and other objects that are currently stored in memory.

• Type a <- 1 in Console, and then hit Enter.

Setting the Tools

RStudio Environment

• Plots Pane contains any graphics that you generate from your R code.

Setting the Tools

R Packages and tidyverse

• R packages are collections of R functions, compiled code, and data that are combined in a structured format.

• Several R packages come with numerous pre-built functions that can perform a wide range of data analysis tasks.

Setting the Tools

tidyverse

• The tidyverse is a collection of R packages designed for data science that share an underlying design philosophy, grammar, and data structures.

• tidyverse includes a lot of R packages, including ggplot2, dplyr, and tidyr.

• The tidyverse packages work harmoniously together to make data manipulation, exploration, and visualization more.

Setting the Tools

Installing R packages with install.packages("packageName")

install.packages("tidyverse")

• R packages can be easily installed from within R using a base-R function install.packages("packageName").
  • To install the R package tidyverse, type and run the following command from R console:
• While running the above codes, you may encounter the pop-up question, and you can answer “No”

Setting the Tools

Loading R packages with library(packageName)

library(tidyverse)
mpg

• Once installed, a package is loaded into an R session using a base-R function library(packageName) so that R package’s functions and data can be used.
  • To load the R package tidyverse, type and run the following commands from a R script:
• mpg is the data.frame provided by the R package ggplot2, one of the R pakcages in tidyverse.
  • Since tidyverse is installed, ggplot2 package is already installed.

Setting the Tools

RStudio Options Setting

• This option menu is found by menus as follows:
  • Tools \(>\) Global Options
• Check the boxes as in the left.
• Choose the option Never for Save workspace to .RData on exit:

Setting the Tools

Workflow: Naming and File Management

• Save your class R script for each class.
• I use the following style of file name for class R script:
  • e.g., danl-101-lec-04-2024-0905.R
• Do not have any space when you name a file.
  • It is recommended to use all lower cases.

Setting the Tools

Workflow: Code and comment style

• The two main principles for coding and managing data are:
  • Make things easier for your future self.
  • Don’t trust your future self.
• The # mark is R’s comment character.
  • In R scripts (*.R files), # indicates that the rest of the line is to be ignored.
  • Write comments before the line that you want the comment to apply to.

Setting the DANL Tools

Workflow: Shortcuts in Posit Cloud (RStudio)

• Windows
  • Alt + - adds an assignment operator
  • Ctrl + Enter runs a current line of code
  • Ctrl + Shift + C makes a comment (#)
  • Ctrl + Shift + R makes a section (# Section - - - -)

• Mac
  • option + - adds an assignment operator
  • command + return runs a current line of code
  • command + shift + C makes a comment (#)
  • command + shift + R makes a section (# Section - - - -)

Setting the Tools

Workflow: Shortcuts in Posit Cloud (RStudio)

• Ctrl (command for Mac Users) + Z undoes the previous action.
• Ctrl (command for Mac Users) + Shift + Z redoes when undo is executed.

Setting the Tools

Workflow: Shortcuts in Posit Cloud (RStudio)

• Ctrl (command for Mac Users) + F is useful when finding a phrase (and replace the phrase) in the RScript.

Setting the Tools

Workflow: Auto-completion

libr

• Auto-completion of command is useful.
  • Type libr in the RScript in RStudio and wait for a second.

Setting the Tools

Workflow: STOP icon

• When the code is running, RStudio shows the STOP icon ( 🛑 ) at the top right corner in the Console Pane.
  • Do not click it unless if you want to stop running the code.

R Basics

R Basics

Values, Variables, and Types

• A value is datum (literal) such as a number or text.

• There are different types of values:

  • 352.3 is known as a float or double;
  • 22 is an integer;
  • “Hello World!” is a string.

R Basics

Values, Variables, and Types

a <- 10    # The most popular assignment operator in R is `<-`.
a

• A variable is a name that refers to a value.
  • We can think of a variable as a box that has a value, or multiple values, packed inside it.
• A variable is just a name!

R Basics

Objects

• Sometimes you will hear variables referred to as objects.

• Everything that is not a literal value, such as 10, is an object.

R Basics

Assignment

x <- 2
x < - 3

• What is going on here?

• The shortcut for the assignment <- is:

  • Windows: Alt + -
  • Mac: option + -

R Basics

Assignment

x <- 2
y <- x + 12

• In programming code, everything on the right side needs to have a value.
  • The right side can be a literal value, or a variable that has already been assigned a value, or a combination.
• When R reads y <- x + 12, it does the following:
  1. Sees the <- in the middle.
  2. Knows that this is an assignment.
  3. Calculates the right side (gets the value of the object referred to by x and adds it to 12).
  4. Assigns the result to the left-side variable, y.