The “apply” Function in R

• Package: Base R (no specific package required)

• Purpose: Applies a function to the rows or columns of a matrix, or the margins of an array.

• General Class: Data Manipulation

• Required Argument(s):

• X: A matrix or array.

• MARGIN: A vector indicating which margins should be retained after applying the function.

• FUN: The function to apply.

• Notable Optional Arguments:

• ...: Additional arguments passed to the function specified by FUN.

• simplify: Logical; if TRUE, attempts to reduce the result to a simpler form.

• USE.NAMES: Logical; if TRUE and X is a named array, the names are used to name the result.

• Example:

• # Example data for using the apply function
  matrix_example <- matrix(1:6, nrow = 2, ncol = 3)
  
  # Apply the sum function to each column of the matrix
  result <- apply(matrix_example, MARGIN = 2, FUN = sum)
  
  # Display the result
  print(result)

• In this example, the apply function is used to apply the sum function to each column of the matrix_example. The resulting result vector contains the sums of the columns. The apply function is versatile and can be used to apply a function along the rows or columns of a matrix or the margins of an array.