Aggregate Rankings

Aggregate rankings, returning an "aggregated_rankings" object of the unique rankings and their frequencies. The frequencies can be extracted via the function freq().

Usage

# S3 method for rankings
aggregate(x, freq = NULL, ...)

as.aggregated_rankings(x, ...)

# S3 method for aggregated_rankings
[(x, i, j, ..., drop = FALSE, as.aggregated_rankings = TRUE)

freq(x)

Arguments

x

A "rankings" object for aggregate(); an object that can be coerced to a "aggregated_rankings" object for as.aggregated_rankings(), otherwise an "aggregated_rankings" object.

freq

A vector of frequencies for rankings that have been previously aggregated.

...

Additional arguments, currently unused.

i

indices specifying rankings to extract, as for [.

j

indices specifying items to extract, as for [.

drop

if TRUE return single row/column matrices as a vector.

as.aggregated_rankings

if TRUE create an "aggregated_rankings" object from the indexed rankings. Otherwise index the underlying matrix of ranks and return in a data frame with the corresponding frequencies.

Value

A data frame of class "aggregated_rankings", with columns

ranking

A "rankings" object of the unique rankings.

freq

The corresponding frequencies.

Methods are available for rbind() and as.matrix().

See also

preflib() for an object that can be coerced to an "aggregated_rankings" object.

Examples

# create a rankings object with duplicated rankings
R <- matrix(c(1, 2, 0, 0,
              0, 1, 2, 3,
              2, 1, 1, 0,
              1, 2, 0, 0,
              2, 1, 1, 0,
              1, 0, 3, 2), nrow = 6, byrow = TRUE)
colnames(R) <- c("apple", "banana", "orange", "pear")
R <- as.rankings(R)

# aggregate the rankings
A <- aggregate(R)

# subsetting applies to the rankings, e.g. first two unique rankings
A[1:2]
#>                  ranking freq
#> 1         apple > banana    2
#> 2 banana > orange > pear    1

# (partial) rankings of items 2 to 4 only
A[, 2:4]
#> Recoded rankings that are not in dense form
#> Rankings with only 1 item set to `NA`
#>                  ranking freq
#> 1                   <NA>    2
#> 2 banana > orange > pear    1
#> 3        banana = orange    2
#> 4          pear > orange    1

# convert to a matrix
as.matrix(A)
#>      apple banana orange pear freq
#> [1,]     1      2      0    0    2
#> [2,]     0      1      2    3    1
#> [3,]     2      1      1    0    2
#> [4,]     1      0      3    2    1

# frequencies are automatically used as weights by PlackettLuce()
mod <- PlackettLuce(A)
mod$weights
#> [1] 2 1 2 1