inst/examples/get_mallows_loglik_example.R

In BayesMallows: Bayesian Preference Learning with the Mallows Rank Model

# Simulate a sample from a Mallows model with the Kendall distance

n_items <- 5
mydata <- sample_mallows(
  n_samples = 100,
  rho0 = 1:n_items,
  alpha0 = 10,
  metric = "kendall")

# Compute the likelihood and log-likelihood values under the true model...
get_mallows_loglik(
  rho = rbind(1:n_items, 1:n_items),
  alpha = c(10, 10),
  weights = c(0.5, 0.5),
  metric = "kendall",
  rankings = mydata,
  log = FALSE
  )

get_mallows_loglik(
  rho = rbind(1:n_items, 1:n_items),
  alpha = c(10, 10),
  weights = c(0.5, 0.5),
  metric = "kendall",
  rankings = mydata,
  log = TRUE
  )

# or equivalently, by using the frequency distribution
freq_distr <- compute_observation_frequency(mydata)
get_mallows_loglik(
  rho = rbind(1:n_items, 1:n_items),
  alpha = c(10, 10),
  weights = c(0.5, 0.5),
  metric = "kendall",
  rankings = freq_distr[, 1:n_items],
  observation_frequency = freq_distr[, n_items + 1],
  log = FALSE
  )

get_mallows_loglik(
  rho = rbind(1:n_items, 1:n_items),
  alpha = c(10, 10),
  weights = c(0.5, 0.5),
  metric = "kendall",
  rankings = freq_distr[, 1:n_items],
  observation_frequency = freq_distr[, n_items + 1],
  log = TRUE
  )