adjacency {prefio}

Create an Adjacency Matrix for a set of Preferences

Description

Convert a set of preferences to an adjacency matrix summarising wins and losses between pairs of items

Usage

adjacency(object, weights = NULL, ...)

Arguments

object

a preferences object, or an object that can be coerced by as.preferences.

weights

an optional vector of weights for the preferences.

...

further arguments passed to/from methods.

Details

For a preferences object with N items, the adjacency matrix is an N by N matrix, with element (i, j) being the number of times item i wins over item j. For example, in the preferences {1} > {3, 4} > {2}, item 1 wins over items 2, 3, and 4, while items 3 and 4 win over item 2.

If weights is specified, the values in the adjacency matrix are the weighted counts.

Value

An N by N matrix, where N is the number of items.

Examples

X <- matrix(c(
  2, 1, 2, 1, 2,
  3, 2, 0, 0, 1,
  1, 0, 2, 2, 3
), nrow = 3, byrow = TRUE)
X <- as.preferences(X, format = "ranking", item_names = LETTERS[1:5])
adjacency(X)

adjacency(X, weights = c(1, 1, 2))