What are global variables in R?
Overview
Global variables in R are variables created outside a given function.
A global variable can also be used both inside and outside a function.
Code example
Let’s learn to create a global variable outside a function while using this same variable inside the function:
# creating a variablemyGlobalvariable <- "awesome"# creating a function# using the variable inside the functionmy_function <- function() {paste("R is", myGlobalvariable)}# calling the functionmy_function()
Code explanation
- Line 2: We create a variable
my_global_variable. - Line 5: We create a function
my_function. - Line 6: We use the global variable,
my_global_variable, inside themy_functionfunction. - Line 11: We call the
my_functionfunction.
When a variable is created with the same name as a global variable inside a given function, it is called the local variable. This variable can only be used inside the given function. The global variable will now have the same original value whenever it is printed outside the function. However, the local variable with the same name will print its value only when printed inside the function.
The code example below explains it all:
# creating a global variablemy_global_variable <- "This is the global variable"# creating a function# creating a local variablemy_function <- function() {my_global_variable <- "This is the local variable"paste("R is", my_global_variable)}# calling the variabe inside the functionmy_function()# calling the variable ouside the functionmy_global_variable
Code explanation
- Line 2: We create a global variable variable called
my_global_variable. - Line 6: We create the
my_functionfunction. - Line 7: We create a local variable with the same name as
my_global_variable. - Line 12: We call
my_function. - Line 13: We call the
my_global_variableoutside the function.
When you print
my_global_variable, it will return"This is the global variable"because we are printing it outside the function.