What is the global assignment operator in R?
Overview
In R, the global assignment operator (<<-) creates a global variable inside a function.
Note: We can also create a global variable outside of a function. The
<<-operator helps us make a variable that belongs to the global scope even when defined in a function.
Code
The code given below illustrates this:
# creating a functionmy_function <- function() {# creating a variable using the global assignment operatormy_variable <<- "interesting!"paste("R is", my_variable)}# calling the functionmy_function()# printing the variableprint(my_variable)
Explanation
- Line 2: We create a function called
my_function. - Line 5: We create a global variable, called
my_variable, inside the function we created. - Line 6: We display the value of variable the
my_variable. - Line 10: We call the function
my_function. - Line 13: We print the global variable
my_variableoutside the function.
We can create a global variable within a function, using the global assignment operator <<-.
Note: Interestingly, we can refer to a variable and change the value of the variable that we created inside a function, by using the global assignment operator.
Code
The code given below illustrates this:
# creating a global variablemy_variable <- "awesome"# creating a functionmy_function <- function() {# using the global assignment operatormy_variable <<- "fantastic"paste("R is", my_variable)}# calling the functionmy_function()# calling the variable outside the functionpaste("R is", my_variable)
Explanation
- Line 2: We create a global variable called
my_variable. - Line 5: We create a function called
my_function. - Line 8: We refer to the global variable
my_variable, which we created initially, using the global assignment operator<<-and change its value to a new value. - Line 9: We return the global variable
my_variable. - Line 13: We call the function
my_function. - Line 15: We print the global variable
my_variable.
We changed the value of a global variable from my_variable = awesome to my_variable = fantastic by referring to the global variable inside of a function, using the global assignment operator <<-.
