Argument matching is the process of determining which arguments a function should use when it is called. There are two ways to match arguments in R: positional matching and named matching.
Positional matching is the default way that arguments are matched in R. When you call a function, the arguments are matched to the function's formal arguments in the order that they are listed in the function definition. For example, the following code calls the `rnorm()` function to generate a random normal variable:
rnorm(100, 2, 1)
The first argument to `rnorm()` is the number of observations to generate. The second argument is the mean of the normal distribution. The third argument is the standard deviation of the normal distribution. In this case, the arguments are matched to the formal arguments of `rnorm()` in the order that they are listed in the function definition.
Named matching allows you to match arguments by name. This can be useful if you have a long list of arguments and you want to specify the value of a specific argument without having to remember its position in the list. For example, the following code calls the `rnorm()` function to generate a random normal variable with a mean of 3 and a standard deviation of 2:
rnorm(100, mean = 3, sd = 2)
In this case, the `mean` and `sd` arguments are matched by name to the corresponding formal arguments of `rnorm()`.
You can also mix positional matching and named matching. For example, the following code calls the `rnorm()` function to generate a random normal variable with a mean of 3 and a standard deviation of 2, and then stores the result in a variable called `x`:
x <- rnorm(100, mean = 3, sd = 2)
In this case, the `mean` argument is matched by name and the `sd` argument is matched by position.
Argument matching is a powerful feature of R that allows you to call functions in a flexible way.
