Learn why writing your own functions is useful, how to convert a script into a function, and what order you should include the arguments.

Why you should use functions

Calling functions

The benefits of writing functions

Converting scripts into functions

Converting a script to a function

Your first function: tossing a coin

Inputs to functions

Multiple inputs to functions

Y kant I reed ur code?

Data or detail?

Renaming GLM

How to Write a Function

Learn how to set defaults for arguments, how to pass arguments between functions, and how to check that users specified arguments correctly.

Default arguments

Numeric defaults

Logical defaults

NULL defaults

Categorical defaults

Passing arguments between functions

Harmonic mean

Dealing with missing values

Passing arguments with ...

Checking arguments

Throwing errors with bad arguments

Custom error logic

Fixing function arguments

All About Arguments

Learn how to return early from a function, how to return multiple values, and understand how R decides which variables exist.

Returning values from functions

Returning early

Returning invisibly

Returning multiple values from functions

Returning many things

Returning metadata

Environments

Creating and exploring environments

Do variables exist?

Scope and precedence

Code choices

The code gives a result

The code throws an error

Can a function find its variables?

Can you access variables from inside functions?

Variable precedence 1

Variable precedence 2

Return Values and Scope

Apply your function writing skills to a case study involving data preparation, visualization, and modeling.

Grain yields and unit conversion

Converting areas to metric 1

Converting areas to metric 2

Converting yields to metric

Applying the unit conversion

Visualizing grain yields

Plotting yields over time

A nation divided

Plotting yields over time by region

Modeling grain yields

Running a model

Making yield predictions

Do it all over again

Congratulations

Case Study on Grain Yields

Snake River visits

Standard & Poor 500 price/earnings ratios

NASS corn yields

NASS wheat yields

NASS barley yields

Being able to write your own functions makes your analyses more readable, with fewer errors, and more reusable from project to project. Function writing will increase your productivity more than any other skill!  In this course you'll learn the basics of function writing, focusing on the arguments going into the function and the return values. You'll be writing useful data science functions, and using real-world data on Wyoming tourism, stock price/earnings ratios, and grain yields.

Introduction to the Tidyverse

Intermediate R

Learn how to write efficient, reusable functions in R by understanding the basics of function writing, focusing on the arguments and the return values.

Introduction to Writing Functions in R

Take your R skills up a notch by learning to write efficient, reusable functions. 

Scientifique de données associé en R

R Développeur

Principes de base de la programmation R

Can a function find its variables?

Introduction to Writing Functions in R

Exercice interactif pratique