R Variable Names (Identifiers)

 R Variable Names (Identifiers)

In R, variable names are also called identifiers.

They are used to identify variables, functions, and objects in a program.

 1. Rules for R Variable Names

  •  Must start with a letter (a–z / A–Z) or a dot (.)
  •  Can contain letters, numbers, dots (.), and underscores (_)
  •  Must not start with a number
  •  Must not be a reserved keyword

Valid Variable Names



 

 Invalid Variable Names



 

 2. Case Sensitivity

R is case-sensitive, so these are different:



 

 3. Reserved Keywords in R

These words cannot be used as variable names:

if, else, repeat, while, function,
TRUE, FALSE, NULL, NA, Inf, NaN

 4. Using Dot (.) in Variable Names



 

  •  Valid
  •  Avoid starting with ., as some system variables use it.

 5. Using Underscore (_) in Variable Names



 

  • Preferred naming style
  • Improves readability

 6. Length of Variable Names

  • No fixed limit, but keep names short and meaningful

  • Avoid very long names

 Bad:



 

 Good:



 

7. Best Naming Conventions (Recommended)

✔ Use lowercase letters
✔ Use underscore (_) between words
✔ Choose meaningful names

Examples:

student_age <- 20
total_salary <- 50000
is_passed <- TRUE

 8. Check if a Name is Valid

make.names("student-name")

Output:

[1] "student.name"

 Summary

  • Variable names are called identifiers

  • Must start with letter or dot

  • No spaces or special symbols

  • Case-sensitive

  • Follow good naming conventions for clean code

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