The “expand” Function in R

• Package: tidyr

• Purpose: To create a complete set of combinations from the combinations of existing data.

• General Class: Data Reshaping

• Required Argument(s):

• None.

• Notable Optional Arguments:

• data: A data frame to manipulate

• ...: Columns to expand, along with additional values to fill.

• Example (with Explanation):

• # Load necessary packages
  library(tidyr)
  
  # Create a sample data frame
  data <- data.frame(
  Group = c("A", "B"),
  ID = 1:2
  )
  
  # Expand the data frame to include all combinations of 'Group' and 'ID'
  # The tidyr package is explicitly given because my system used...
  # the expand function from the Matrix package by default.
  result <- tidyr::expand(data, Group, ID = 1:3)
  
  # Display the result
  print(result)

• In this example, the expand function from the tidyr package is used to expand the sample data frame data. The resulting data frame “result” includes all combinations of ‘Group’ and ‘ID’, with ‘ID’ values ranging from 1 to 3. This function is useful for creating a complete set of combinations, especially when some combinations may not exist in the original data.