R Programming By Example

Optional arguments

When creating functions, you may specify a default value for an argument, and if you do, then the argument is considered optional. If you do not specify a default value for an argument, and you do not specify a value when calling a function, you will get an error if the function attempts to use the argument.

In the following example, we show that if a single numeric vector is passed to our l2_norm() function as it stands, it will throw an error, but if we redefine it to make the second vector optional, then we will simply return the first vector's norm, not the distance between two different vectors To accomplish this, we will provide a zero-vector of length one, but because R repeats vector elements until all the vectors ...