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R Global Variables

Global variables in R are variables that are defined outside any function and can be accessed and modified from any part of the code, including within functions. However, modifying global variables inside functions should be done carefully to avoid unintended side effects.

Key Topics

Global Variable Example

# Example of a global variable
x <- 10  # Global variable

modify_global <- function() {
    x <<- x + 5  # Modifying the global variable using '<<-'
}

# Calling the function to modify the global variable
modify_global()
print(x)

Output:

[1] 15

Code Explanation: The variable x is defined globally and modified inside the modify_global function using the <<- operator, which updates the global variable x.

Best Practices

While global variables can be useful, it is best to minimize their use to reduce the risk of unexpected behavior. Instead, prefer using local variables within functions and return values explicitly when possible.

Key Takeaways

  • Global variables are accessible throughout the entire R script.
  • The <<- operator is used to modify global variables inside functions.
  • Use global variables judiciously to maintain code readability and prevent unintended side effects.
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