context("Optimal dispersion")
library("anticlust")

test_that("Output format is as expected for optimal_dispersion()", {
  N <- 30
  M <- 5
  K <- 3
  data <- matrix(rnorm(N*M), ncol = M)
  distances <- dist(data)
  
  opt <- optimal_dispersion(distances, K = K)

  groups_heuristic <- anticlustering(
    distances, 
    K = K,
    method = "local-maximum", 
    objective = "dispersion", 
    repetitions = 10
  )
  expect_true(dispersion_objective(distances, opt$groups) >= dispersion_objective(distances, groups_heuristic))
  
  expect_true(all(sort(table(opt$groups)) == sort(table(initialize_clusters(N, K, NULL)))))
  
  
  # test for unequal group sizes (groups differ by 1 at most)
  N <- 28
  M <- 5
  K <- 3
  data <- matrix(rnorm(N*M), ncol = M)
  distances <- dist(data)
  
  opt <- optimal_dispersion(distances, K = K)
  
  groups_heuristic <- anticlustering(
    distances, 
    K = K,
    method = "local-maximum", 
    objective = "dispersion", 
    repetitions = 10
  )
  expect_true(dispersion_objective(distances, opt$groups) >= dispersion_objective(distances, groups_heuristic))
  expect_true(all(sort(table(opt$groups)) == sort(table(initialize_clusters(N, K, NULL)))))


  # now "truly" unequal group sizes 
  K <- c(10, 12, 6)
  opt <- optimal_dispersion(distances, K = K)
  
  groups_heuristic <- anticlustering(
    distances, 
    K = K,
    method = "local-maximum", 
    objective = "dispersion", 
    repetitions = 10
  )
  
  expect_true(dispersion_objective(distances, opt$groups) >= dispersion_objective(distances, groups_heuristic))
  expect_true(all(sort(table(opt$groups)) == sort(K)))
  
  # another grouping, more extreme case
  K <- c(2, 2, 24)
  opt <- optimal_dispersion(distances, K = K)
  
  groups_heuristic <- anticlustering(
    distances, 
    K = K,
    method = "local-maximum", 
    objective = "dispersion", 
    repetitions = 10
  )
  
  expect_true(dispersion_objective(distances, opt$groups) >= dispersion_objective(distances, groups_heuristic))
  expect_true(all(sort(table(opt$groups)) == sort(K)))
  
})