Convert a set of rankings to a list of choices, alternatives, and rankings. The choices and the corresponding alternatives make up the exchangeable part of the Plackett-Luce with ties.
Arguments
- rankings
a
"rankings"object, or an object that can be coerced byas.rankings.- names
logical: if
TRUEuse the object names in the returned"choices"object, else use object indices.
Value
A data frame of class "choices" with elements:
- choices
A list where each element represents the set of items chosen for a single rank in the ranking.
- alternatives
A list where each element represents the set of items to choose from for a single rank in the ranking.
- ranking
A list where each element represents the ranking that the choice belongs to.
The list stores the number of choices and the names of the objects as the
attributes "nchoices" and "objects" respectively.
Examples
R <- matrix(c(1, 2, 0, 0,
4, 1, 2, 3,
2, 1, 1, 1,
1, 2, 3, 0,
2, 1, 1, 0,
1, 0, 3, 2), nrow = 6, byrow = TRUE)
colnames(R) <- c("apple", "banana", "orange", "pear")
actual_choices <- choices(R, names = TRUE)
actual_choices[1:6,]
#> Ranking: 1
#> --------------
#> {apple} from {apple, banana}
#> {banana} from {banana}
#> ==============
#> Ranking: 2
#> --------------
#> {banana} from {apple, banana, orange, pear}
#> {orange} from {apple, orange, pear}
#> {pear} from {apple, pear}
#> {apple} from {apple}
#> ==============
coded_choices <- choices(R, names = FALSE)
coded_choices[1:2,]
#> Ranking: 1
#> --------------
#> {1} from {1, 2}
#> {2} from {2}
#> ==============
as.data.frame(coded_choices)[1:2,]
#> choices alternatives ranking
#> 1 1 1, 2 1
#> 2 2 2 1
attr(coded_choices, "objects")
#> [1] "apple" "banana" "orange" "pear"