tests/testthat/test-mt_sim_brownian_motion.R

In move2: Processing and Analysing Animal Trajectories

test_that("move sim error checking", {
  expect_error(mt_sim_brownian_motion(sigma = list(1L, 2L, 3L), tracks = 1L:2L))
  expect_error(mt_sim_brownian_motion(t = list(1L, 2L, 3L), tracks = 2L))
  expect_error(mt_sim_brownian_motion(
    start_location = list(2:1, 1L:2L, 2:3),
    tracks = 1L:2L
  ))
  expect_error(mt_sim_brownian_motion(
    start_location = list(2:1, 1L:2L, 1L:3L),
    tracks = 1L:3L
  ))
  expect_error(mt_sim_brownian_motion(t = 1L:4L, tracks = "a", sigma = 1L:4L))
  expect_error(mt_sim_brownian_motion(
    t = 1L:4L,
    tracks = "a",
    sigma = c(1.0, -1.0, 1.0)
  ))
  expect_error(mt_sim_brownian_motion(t = 1L:4L, tracks = "a", sigma = -1.0))
  expect_error(mt_sim_brownian_motion(
    t = c(1L:4L, 3L),
    tracks = "a",
    sigma = 1.0
  ))
  expect_no_error(mt_sim_brownian_motion(
    t = 1L:4L,
    tracks = "a",
    sigma = Vectorize(function(x) x)
  ))
  expect_no_error(mt_sim_brownian_motion(
    t = 0L:4L,
    tracks = "a",
    sigma = Vectorize(function(x) x)
  ))
  expect_error(mt_sim_brownian_motion(
    t = -1L:4L,
    tracks = "a",
    sigma = Vectorize(function(x) x)
  ))
})
test_that(" duplicate track id", {
  expect_error(
    mt_sim_brownian_motion(tracks = c("a", "b", "b")),
    "There is a duplicated name in the"
  )
})
test_that("different track input types", {
  expect_identical(
    mt_sim_brownian_motion(1, tracks = 1L) |> mt_track_id(),
    1L
  )
  expect_identical(
    mt_sim_brownian_motion(1, tracks = 2L) |> mt_track_id(),
    c(1L, 2L)
  )
  expect_identical(
    mt_sim_brownian_motion(1, tracks = 5:7) |> mt_track_id(),
    5:7
  )
  expect_identical(
    mt_sim_brownian_motion(1, tracks = "a") |> mt_track_id(),
    c("a")
  )
  expect_identical(
    mt_sim_brownian_motion(1, tracks = c("a", "l")) |> mt_track_id(),
    c("a", "l")
  )
  expect_identical(
    mt_sim_brownian_motion(1, tracks = factor(4:5)) |> mt_track_id(),
    factor(4:5)
  )
  expect_identical(
    mt_sim_brownian_motion(1, tracks = factor(4L)) |> mt_track_id(),
    factor(4L)
  )
})
test_that("move with timestamps of different types", {
  expect_identical(
    mt_sim_brownian_motion(
      as.POSIXct(1L:4L, origin = "1970-1-1"),
      tracks = 2L
    ) |>
      mt_time(),
    as.POSIXct(c(1L:4L, 1L:4L), origin = "1970-1-1")
  )
  expect_identical(
    mt_sim_brownian_motion(c(1L:6L, 9L), tracks = 1L) |> mt_time(),
    c(1L:6L, 9L)
  )
  expect_identical(
    mt_sim_brownian_motion(list(c(1L:6L, 9L), 9L:12L), tracks = 2L) |>
      mt_time(),
    c(c(1L:6L, 9L), 9L:12L)
  )
  expect_identical(
    mt_sim_brownian_motion(as.Date("2020-1-1") + 1L:3L, tracks = 1L) |>
      mt_time(),
    as.Date("2020-1-1") + 1L:3L
  )
})
test_that("sigma steps", {
  expect_equal(
    (mt_sim_brownian_motion(c(1, 2, 2, 3), tracks = 1L) |> mt_distance())[2],
    0,
    ignore_attr = TRUE
  )
  expect_equal(
    (mt_sim_brownian_motion(c(1L:4L), sigma = c(1.0, 0.0, 4.0), tracks = 1L) |>
      mt_distance())[2],
    0,
    ignore_attr = TRUE
  )
})
test_that("start_locations", {
  expect_identical(
    mt_sim_brownian_motion(
      1,
      sigma = 0.25,
      letters[1L:4L],
      list(c(0, 0), c(10, 0), c(0, 10), c(10, 10))
    ) |>
      sf::st_coordinates(),
    structure(
      c(0, 10, 0, 10, 0, 0, 10, 10),
      dim = c(4L, 2L),
      dimnames = list(NULL, c("X", "Y"))
    )
  )
})
test_that("function works", {
  skip_if_not_installed("sf", minimum_version = "1.0-23")
  expect_identical(
    mt_sim_brownian_motion(sigma = function(x) {
      return(rep(0, length(x)))
    }) |>
      sf::st_geometry() |>
      unique(),
    sf::st_sfc(sf::st_point(c(0.0, 0.0)))
  )
})

test_that("sigma has same result for function or direct", {
  expect_equal(
    {
      set.seed(3)
      mt_sim_brownian_motion(sigma = Vectorize(function(x) 5.6), t = c(1, 6, 8))
    },
    {
      set.seed(3)
      mt_sim_brownian_motion(sigma = 5.6, t = c(1.0, 6.0, 8.0))
    },
    tolerance = 10e-10
  )

  expect_identical(
    {
      set.seed(7L)
      mt_sim_brownian_motion(
        sigma = Vectorize(function(x) ifelse(x < 5, 5.6, 1.2)),
        t = c(1.0, 5.0, 8.0)
      )
    },
    {
      set.seed(7)
      mt_sim_brownian_motion(sigma = c(5.6, 1.2), t = c(1.0, 5.0, 8.0))
    }
  )
})
test_that("sigma values are ok", {
  expect_equal(
    sd(apply(
      sf::st_coordinates(mt_sim_brownian_motion(
        t = 2L * (1L:100000L),
        tracks = 1L,
        sigma = 4.3
      )),
      2,
      diff
    )),
    sqrt(2.0 * 4.3^2),
    tolerance = 0.005
  )
  expect_equal(
    sd(apply(
      sf::st_coordinates(mt_sim_brownian_motion(
        t = 1L:100000L,
        tracks = 1L,
        sigma = 4.3
      )),
      2,
      diff
    )),
    4.3,
    tolerance = 0.005
  )
})
test_that("sigma length check", {
  expect_error(
    mt_sim_brownian_motion(
      sigma = list(1:10, 1:9, 1),
      tracks = 2
    ),
    "is a list the length should match the length of the number of desired tracks"
  )
  expect_error(
    mt_sim_brownian_motion(
      sigma = list("a", 1),
      tracks = 2
    ),
    "The values of `sigma` should be <numeric>, the current class is <character"
  )
})