The “sub” Function in R

• Package: Base R (No specific package, it’s a built-in function)

• Purpose: To replace the first occurrence of a pattern in a character vector with a specified replacement string.

• General Class: String Manipulation

• Required Argument(s):

• pattern: A character string or a regular expression specifying the pattern to be replaced.

• replacement: A character string specifying the replacement for the pattern.

• x: A character vector in which the replacement is to be made.

• Notable Optional Arguments:

• ignore.case: Logical. If TRUE, the pattern matching is case-insensitive. The default is FALSE.

• perl: Logical. If TRUE, use Perl-style regular expressions. The default is FALSE.

• Example:

• # Example usage
  sentence <- "The quick brown fox jumps over the lazy dog."
  
  # Replace the first occurrence of "fox" with "cat" in the sentence
  modified_sentence <- sub(pattern = "fox", replacement = "cat", x = sentence)
  
  print(modified_sentence)

• In this example, sub is a built-in function in base R, and it is used to replace the first occurrence of the specified pattern (“fox”) in a character vector (sentence) with the specified replacement string (“cat”). The pattern, replacement, and x arguments are required, and additional optional arguments, such as ignore.case and perl, can be used to modify the behavior of the pattern matching. The result is a character vector with the specified replacement for the first occurrence of the pattern.