Functions are a fundamental building block of R. To master many of the more advanced techniques in this book, you need a solid foundation in how they work. We've already used a few functions above since you can't really do anything interesting in R without them. They are just what you remember from your mathematics classes, a way to transform inputs into outputs. Specifically in R, a function is an object that takes other objects as inputs, called arguments, and returns an output object. Most functions are in the following form f(argument_1, argument_2, ...). Where f is the name of the function, and argument_1, argument_2, and so on are the arguments to the function.
Before we continue, we should briefly ...
