In R, a function is a reusable piece of code that takes in some input and produces some output. Functions are defined using the `function()` keyword. The syntax for defining a function in R is as follows:
function(arguments) {
# Body of the function
return(value)
}
The `arguments` argument is a list of the names of the arguments that the function takes in. The `Body of the function` is the code that the function executes. The `return(value)` statement returns the value of the function.
For example, the following code defines a function called `add()` that adds two numbers together:
add <- function(x, y) {
z <- x + y
return(z)
}
The `add()` function has two arguments: `x` and `y`. These arguments are the numbers that the `add()` function needs to add together. The `Body of the function` simply adds the values of `x` and `y` together and stores the result in the variable `z`. The `return(z)` statement returns the value of `z`, which is the sum of `x` and `y`.
To call the `add()` function, you would pass the values of the arguments to the function. For example, the following code calls the `add()` function and passes the values 1 and 2 to the function:
z <- add(1, 2)
The `add()` function then adds the values 1 and 2 together and stores the result in the variable `z`. The value of `z` is then 3.
Rules for defining functions in R
- The `function()` keyword must be used to define a function.
- The arguments of the function must be specified in a list.
- The body of the function must be a block of code.
- The `return()` statement must be used to return the value of the function.
