R(10), Function
R language has a large number of built-in functions, but user can also create their own functions.
Function Definition
function_name <- function(arg_1, arg_2, ...) {
Function body
}
example:
# Create a function to print squares of numbers in sequence.
new.function <- function(a) {
for(i in 1:a) {
b <- i^2
print(b)
}
}
Call Functions
which means using function
The parameters of a function call can be provided either in the ordered defined in the function, or in a different order but are assigned to the names of the parameters.
# Create a function with arguments.
new.function <- function(a,b,c) {
result <- a * b + c
print(result)
}
# Call the function by position of arguments.
new.function(5,3,11)
# Call the function by names of the arguments.
new.function(a = 11, b = 5, c = 3)
Call functions with default parameters.
# Create a function with arguments.
new.function <- function(a = 3, b = 6) {
result <- a * b
print(result)
}
# Call the function without giving any argument.
new.function()
# Call the function with giving new values of the argument.
new.function(9,5)
Delay evaluation of function parameters means that they are evaluated only when the function body needs them.
# Create a function with arguments.
new.function <- function(a, b) {
print(a^2)
print(a)
print(b)
}
# Evaluate the function without supplying one of the arguments.
new.function(6)
result:
[1] 36
[1] 6
Error in print(b) : argument "b" is missing, with no default