Chapter 4 General Coding
4.1 Objects
Objects are any ‘thing’ that you create in R. They’re shown in your Environment.
There are a huge number of objects in R. The following illstrates a numer of the core object types:
my_string <- 'DfE'
my_number <- 2017
my_boolean <- TRUE
my_vector <- c("a", "b", "c")
my_dataframe <- data.frame(var1 = c(1,2,3,4,5),
var2 = c("a","b","c","d","e"))
my_list <- list(my_string,my_number,my_boolean, my_vector, my_dataframe)Tip:
When naming objects it is useful to do the following:
Make the names meaningful but short e.g. we could call School Workforce Census Table
swfc.Stick to one convention. The standard for R is snake_case. See here for further details on R Style Guide.
To run that code you will first need to create a new script File > New File > R Script.
You can then run line by line by having your cursor on that line or highlight chunks and then doing one of the following:
- Press CTRL + ENTER
- Click ‘Run’ in the top right hand corner of the script window
Tip:
- Double click highlights term
- Triple click highlights line
- Quadruple click highlights entire script
The <- sign is called a get sign. It ‘gets’ the output from the right hand side and attributes it to the object name.
Tip: ALT + - is a shortcut to inputting the get sign.
Activity A3.3: What does typeof(OBJECT NAME) do?
Activity A3.4: Now save your work in the R folder!
Writing the following code will remove a specified object:
Writing the following code will remove all objects:
Activity A3.5: Arguments are the bits of code inside brackets, and if there are multiple arguments they’re separated by commas.
Explain the what the argument inside the second rm in the code above does.
4.2 Comments
Comments are really important for annotating code, so that you and others know exactly what the code does and why.
Here we add a description of what setwd() does:
Tip: