tests/testthat/test-isomorphism.R

In igraph: Network Analysis and Visualization

test_that("isomorphic", {
  g <- graph_(from_literal(A - B - C - A))
  expect_true(isomorphic(g, g))
  expect_true(isomorphic(g, g, method = "direct"))
  expect_true(isomorphic(g, g, method = "vf2"))
  expect_true(isomorphic(g, g, method = "bliss"))

  g2 <- graph_(from_literal(A - B - C))
  expect_false(isomorphic(g, g2))
  expect_false(isomorphic(g, g2, method = "direct"))
  expect_false(isomorphic(g, g2, method = "vf2"))
  expect_false(isomorphic(g, g2, method = "bliss"))
})

test_that("subgraph_isomorphic", {
  g <- graph_(from_literal(A - B - C - D - E - A))
  g2 <- graph_(from_literal(A - B - C - D))

  expect_true(subgraph_isomorphic(g2, g))
  expect_true(subgraph_isomorphic(g2, g, method = "vf2"))
  expect_true(subgraph_isomorphic(g2, g, method = "lad"))

  g3 <- graph_(from_literal(A - B - C - A))
  expect_false(subgraph_isomorphic(g3, g))
  expect_false(subgraph_isomorphic(g3, g, method = "vf2"))
  expect_false(subgraph_isomorphic(g3, g, method = "lad"))
})

test_that("count_isomorphisms", {
  g <- graph_(from_literal(A - B - C - D - A))
  expect_equal(count_isomorphisms(g, g), 8)

  g2 <- graph_(from_literal(A - B - C - A))
  expect_equal(count_isomorphisms(g, g2), 0)
})

test_that("count_subgraph_isomorphisms", {
  g <- graph_(from_literal(A - B - C - D - A))
  g2 <- graph_(from_literal(A - B - C - D))

  expect_equal(count_subgraph_isomorphisms(g2, g, method = "lad"), 8)
  expect_equal(count_subgraph_isomorphisms(g2, g, method = "vf2"), 8)

  g3 <- graph_(from_literal(A - B - C - A))
  expect_equal(count_subgraph_isomorphisms(g3, g, method = "lad"), 0)
  expect_equal(count_subgraph_isomorphisms(g3, g, method = "vf2"), 0)
})

test_that("isomorphisms", {
  g <- graph_(from_literal(A - B - C - D - A))
  g2 <- graph_(from_literal(W - X - Y - Z - W))

  res <- list(
    V(g2)[1, 2, 3, 4],
    V(g2)[1, 4, 3, 2],
    V(g2)[2, 1, 4, 3],
    V(g2)[2, 3, 4, 1],
    V(g2)[3, 2, 1, 4],
    V(g2)[3, 4, 1, 2],
    V(g2)[4, 1, 2, 3],
    V(g2)[4, 3, 2, 1]
  )

  expect_equal(ignore_attr = TRUE, isomorphisms(g, g2), res)

  g3 <- graph_(from_literal(X - Y - Z - X))
  expect_equal(isomorphisms(g, g3), list())
})

test_that("subgraph_isomorphisms, lad", {
  g <- graph_(from_literal(A - B - C - D - A))
  g2 <- graph_(from_literal(Z - X - Y))

  res <- list(
    V(g)[1, 4, 3],
    V(g)[1, 2, 3],
    V(g)[2, 1, 4],
    V(g)[2, 3, 4],
    V(g)[3, 2, 1],
    V(g)[3, 4, 1],
    V(g)[4, 3, 2],
    V(g)[4, 1, 2]
  )

  expect_equal(ignore_attr = TRUE, subgraph_isomorphisms(g2, g, method = "lad"), res)

  g3 <- graph_(from_literal(X - Y - Z - X))
  expect_equal(subgraph_isomorphisms(g3, g, method = "lad"), list())
})

test_that("subgraph_isomorphisms, vf2", {
  g <- graph_(from_literal(A - B - C - D - A))
  g2 <- graph_(from_literal(Z - X - Y))

  res <- list(
    V(g)[1, 2, 3],
    V(g)[1, 4, 3],
    V(g)[2, 1, 4],
    V(g)[2, 3, 4],
    V(g)[3, 2, 1],
    V(g)[3, 4, 1],
    V(g)[4, 1, 2],
    V(g)[4, 3, 2]
  )

  expect_equal(ignore_attr = TRUE, subgraph_isomorphisms(g2, g, method = "vf2"), res)

  g3 <- graph_(from_literal(X - Y - Z - X))
  expect_equal(subgraph_isomorphisms(g3, g, method = "vf2"), list())
})