R Programming: Building Your First Function

Name: R Programming: Building Your First Function
Author: David Christensen

Master the essentials of R programming with flow control, function creation, and error handling

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Course: On-Demand

Hi, I'm David Christensen, and in these lessons, you will learn how to create your first function in R. You will learn about the structure and syntax of functions, including how to define arguments and return values. In this lesson, I'll introduce you to common flow control functions, such as if, else, and the for loop. Flow control functions allow you to determine when code is run based on a logical test. The first control structure we'll look at is the function if, else. The if, else function takes three arguments. The first argument is the conditional. The second value is what happens if something is true, and the third value is what happens if the value is false. Let's say we have an if, else where we have 1 greater than 2, and in the second position, we'll say yes, and in the third position, we'll say no. Let's go ahead and run this code. It evaluates as no. No is the returned value since 1 is not greater than 2. If we change the test around so that 1 is less than 2, the function would evaluate as yes. Next, let's have a look at the if function. If is fairly similar to if, else. One of the main differences is that it does not require an else clause. Also, multiple if statements can be chained together. The if statement takes a conditional. This could be some kind of logical test, or you could even put the value true or false within if. Following the if function, we put curly brackets with whatever code we want to execute if true. I'll put 3 plus 2 within the curly brackets, and this will execute if true. If we change this to if false and try to run the code again, we get no result. The code will not execute unless the statement has evaluated as true. In situations where our if statement evaluates as false, we may want to test if something else is also true or false. We can chain together additional if statements by typing else after our curly brackets, followed by another if statement. Within our if statement, we could have any kind of logical test. The logical test should have a single true or false value, not a vector of trues and falses. If you had a logical vector that you wanted as a scalar, you could use the functions any or the function all to test if any of the values are true or false, or if all the values are true or false. To briefly demonstrate, I'll use the function all with the vector false true. Since one of these is false, the all function will return false as well. At the end of this flow control, if there's some code we want to run, if everything else is false, we can add an else statement after our last else if. Any code in the final else statement will execute if the previous conditions were all false. The function for is a conditional iterative that repeatedly executes a specified number of times. Let's go ahead and run a for statement. Within the parentheses, we need to tell the for statement how many times to run. And this is where we put in the conditional iterative. The way we write this iterative is to say for blank in blank. And so we'll say for i in the vector 1 through 10. This will execute the vector 10 times since the vector 1 through 10 has 10 places. And within this for statement, we can put whatever code we want to execute the specified number of times. So what we'll do is put a print statement and ask it to paste i and the word time. In the console, we see an output has returned 10 times. That's what we wanted. The for loop is great for repeating a section of code a specified number of times. Thanks for watching. Stay tuned for the next lesson where I'll show you how to create a function.

Beginner Provider : David Christensen 4 Lessons · 20m in Arabic, German, English, Spanish, French, Portuguese, Chinese

Course Description

In these lessons, you’ll expand your knowledge of R programming by focusing on essential topics such as flow control, function creation, and error handling. You will learn how to use if() and else() statements to make decisions based on conditions, and how to use for() loops to iterate over data structures. You will also learn how to create custom functions using function() and how to apply the apply() family of functions, including lapply() and sapply(), for efficient data manipulation. Additionally, we’ll cover how to handle errors using stop() and warning() functions within custom functions.

By the end of these lessons, you’ll have a solid understanding of the essentials of R programming, as well as how to apply custom functions to real-world data problems. You’ll also understand how to write efficient, readable, and modular code using the principles of good programming practices.

What You'll Learn

Apply flow control statements, including if() and else() decisions and for() loops to iterate over data structures
Create custom functions using function() to write modular R code
Use the apply() family of functions, including lapply() and sapply(), for efficient data manipulation
Handle errors within custom functions using the stop() and warning() functions
Write efficient, readable, and modular code following good programming practices
Apply custom functions to real-world data problems

Key Takeaways

if() and else() statements let you make decisions based on conditions, while for() loops iterate over data structures.
Custom functions are created in R using function().
The apply() family, including lapply() and sapply(), supports efficient data manipulation.
Errors inside custom functions can be handled with the stop() and warning() functions.
Good programming practices help you write efficient, readable, and modular R code.

Frequently Asked Questions

What topics does this course cover?

It covers flow control, function creation, and error handling in R, including if() and else() statements, for() loops, creating custom functions with function(), the apply() family (lapply() and sapply()), and error handling with stop() and warning().

What skills will I gain from this course?

You will gain skills in R (Programming Language), R Base, RStudio, user-defined and stored functions, function modules, and applying custom functions to real-world data problems.

What will I be able to do by the end of the lessons?

You will have a solid understanding of the essentials of R programming and know how to apply custom functions to real-world data problems, as well as how to write efficient, readable, and modular code using good programming practices.

What lessons are included?

The lessons include Control Structures, Creating and Using Basic Functions, Using the Apply Family of Functions, and Introduction to Error Handling.