Sometimes we want to write a function to do a very specific job, because we cannot find an exact equivalent, and/or the procedure has to be executed a number of times in a piece of code. Most programming languages allow us to define functions. We define the source code for the function, that is, the code that R looks for whenever the function is called.
The example function below outputs a person’s name, along with the number and type of pets they have.
The function code is enclosed within the curly braces {}.
Input:
name_pets<-function(person,cats,dogs){
result<-c(person,cats,dogs)
return(result) #the function returns the last object it sees.
#Adding a return() specifies what to return to
the main program
#But is not strictly necessary here. Try the
code without it.
}
name<-"Andrew"
number_of_cats<-4
number_of_dogs<-1
details<-name_pets(name, number_of_cats,number_of_dogs) #this is the function
call. The arguments passed to the function
#do not have to have the same names as in
the source code.
details #The function output is contained within the object 'details'
#until a command is given to display it.
Output:
'Andrew' '4' '1'
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