If RStudio doesn’t look the way you want (or like our RStudio), then do:
In R Studio Menu Bar go to View Menu –> Panes –> Pane Layout
Workspace/Environment
Tells you what objects are in R
What exists in memory/what is loaded?/what did I read in?
Workspace/History
Shows previous commands. Good to look at for debugging, but don’t rely on it.
Also type the “up” and “down” key in the Console to scroll through previous commands
Workspace/Other Panes
Files - shows the files on your computer of the directory you are working in
Viewer - can view data or R objects
Help - shows help of R commands
Plots - pictures and figures
Packages - list of R packages that are loaded in memory
Getting Started
In R Studio Menu Bar go to File Menu –> New File –> R Script
Save the blank R script as Module1.R
Explaining output on slides
In slides, the R command/code will be in a box, and then directly after it, will be the output of the code starting with [1]
print("I'm code")
[1] "I'm code"
So print("I'm code") is the command and [1] "I'm code" is the output.
Commands/code and output written as inline text will be typewriter blue font. For example code
R as a calculator
You can do basic arithmetic in R, which I surprisingly use all the time.
2+2
[1] 4
2*4
[1] 8
2^3
[1] 8
R as a calculator
The R console is a full calculator
Arithmetic operators:
+, -, /, * are add, subtract, divide and multiply
^ or ** is power
parentheses – ( and ) – work with order of operations
%% finds the remainder
Execute / Run Code
To execute or run a line of code (i.e., command), you just put your cursor on the command and then:
Press Run (which you will find at the top of your Console pane)
OR
Press Cmd + Return (iOS) OR Ctrl + Enter (Windows).
To execute or run multiple lines of code, you need to highlight the code you want to run and then follow option 1 or 2.
Mini exercise
Execute 5+4 from your .R file, and then find the answer 9 in the Console.
Commenting in Scripts
The syntax # creates a comment, which means anything to the right of # will not be executed / run
Commenting is useful to:
Create headers for R Scripts
Create sections within an R Script
Explain what is happening in your code
Commenting an R Script header
Add a comment header to Module1.R. This is the one I typically use, but you may have your own preference. The goal is that you are consistent so that future you / collaborators can make sense of your code.
### Title: Module 1### Author: Amy Winter ### Objective: Mini Exercise - Developing first R Script### Date: 15 July 2024
Commenting to create sections
You can also create sections within your code by ending a comment with 4 hash marks. This is very useful for creating an outline of your R Script. The “Outline” can be found in the top right of the your Source pane
## this # is still a comment### you can use many #'s as you want# sometimes you have a really long comment,# like explaining what you are doing# for a step in analysis. # Take it to another line
I tend to use:
One hash mark with a space to describe what is happening in the following few lines of code
One hash mark with no space after a command to list specifics
# Practicing my arithmetic5+23*59/85+2#5 plus 2
Object - Basic terms
Object - an object is something that can be worked with in R - can be lots of different things!
a scalar / number
a vector
a matrix of numbers
a list
a plot
a function
… many more
Objects
You can create objects from within the R environment and from files on your computer
R uses <- to assign values to an object name
Note: Object names are case-sensitive, i.e. X and x are different
Here are examples of creating five different objects:
Note, c(), paste0(), and matrix() are functions, which we will talk more about in module 2.
Object names - Good coding
In general, any object name can be typed into R.
However, only some are considered “valid”. If you use a non-valid object name, you will have to enclose it in backticks `like this` for R to recognize it.
From the R documentation:
A syntactically valid name consists of letters, numbers and the dot or underline characters and starts with a letter or the dot not followed by a number. Names such as “.2way” are not valid, and neither are the reserved words.
Reserved words: if, else, repeat, while, function, for, in, next, break, TRUE, FALSE, NULL, Inf, NaN, NA, NA_integer_, NA_real_, NA_Complex_, _NA_Character, ..., ..1, ..2, ..3, and so on.
Object names - Good coding
Valid
Invalid
my_object
my-data
the.vector
2data
num12
for
measles_data
.9data
.calc
xX~mŷ_δätą~Xx
Object assingment - Good coding
= and <- can both be used for assignment, but <- is better coding practice, because sometimes = doesn’t work and we want to distinguish between the logical operator ==. We will talk about this more, later.
Mini Exercise
Try creating one or two of these objects in your R script
