tests/testthat/test-walktrap.community.R

In igraph: Network Analysis and Visualization

test_that("cluster_walktrap works", {
  g <- make_graph("Zachary")
  set.seed(42)
  wc <- cluster_walktrap(g)

  expect_that(modularity(g, membership(wc)), equals(modularity(wc)))
  expect_that(
    as.vector(membership(wc)),
    equals(c(
      1, 1, 2, 1, 5, 5, 5, 1, 2, 2,
      5, 1, 1, 2, 3, 3, 5, 1, 3, 1,
      3, 1, 3, 4, 4, 4, 3, 4, 2, 3,
      2, 2, 3, 3
    ))
  )
  expect_that(length(wc), equals(5))
  expect_that(sizes(wc), equals(structure(
    c(9L, 7L, 9L, 4L, 5L),
    .Dim = 5L,
    .Dimnames = structure(
      list(`Community sizes` = c(
        "1", "2", "3", "4",
        "5"
      )),
      .Names = "Community sizes"
    ),
    class = "table"
  )))

  d <- as.dendrogram(wc)
  expect_that(print(d), prints_text("2 branches.*34 members.*height 33"))
  expect_that(
    print(d[[1]]),
    prints_text("2 branches.*20 members.*height 31")
  )
  expect_that(
    print(d[[2]]),
    prints_text("2 branches.*14 members.*height 32")
  )
  m2 <- cut_at(wc, no = 3)
  expect_that(
    modularity(g, m2),
    equals(wc$modularity[length(wc$modularity) - 2],
      tolerance = 1e-7
    )
  )
})