Anatomy of a R command

Basic Anatomy

Almost every R command you run will look like either:

named_object <- function(input_1, input_2, ...)

or

function(input_1, input_2, ...)

What is a function?

A function takes one or more inputs (sometimes it can even take zero inputs), and returns an output.

The output can be almost anything. It could be a dataframe, a variable, a number, a regression, or almost anything else.

Commands that store output in a named object

Commands that store output in a named object look like this:

named_object <- function(input_1, input_2, ...)

This command runs the function with the inputs you give it, then it stores the output in named_object. You can give this object any name you want.

Example

my_dataframe <- read.csv("my_file.csv")
  • This command reads the data from a CSV file called “my_file.csv”, returns it as a dataframe, and stores that dataframe in my_dataframe.
  • read.csv is the function.
  • "my_file.csv" is the input to the function.
  • my_dataframe is the name of the object you’re storing the dataframe in.

See my documentation on read.csv for more info.

Commands that don’t store output

Commands that don’t store output look like this:

function(input_1, input_2, ...)

This command runs the function with the inputs you give it, but the output is not stored anywhere. Instead, the output will be displayed directly in the console.

Example

summary(my_dataframe$my_variable)
  • This command shows summary statistics for the variable my_variable in the dataframe my_data.
  • summary is the function.
  • my_dataframe$my_variable is the input to the function.
  • Since you did not tell R to store the output anywhere, the output gets displayed in the console.

See my documentation on summary for more info.