tests/testthat/test-lsm-p-gyrate.R

In landscapemetrics: Landscape Metrics for Categorical Map Patterns

landscapemetrics_patch_landscape_value <- lsm_p_gyrate(landscape)

test_that("lsm_p_gyrate is typestable", {
    expect_s3_class(lsm_p_gyrate(landscape), "tbl_df")
    expect_s3_class(lsm_p_gyrate(landscape_stack), "tbl_df")
    expect_s3_class(lsm_p_gyrate(landscape_list), "tbl_df")
})

test_that("lsm_p_gyrate returns the desired number of columns", {
    expect_equal(ncol(landscapemetrics_patch_landscape_value), 6)
})

test_that("lsm_p_gyrate can force centroid to be within patch", {

    result_a <- lsm_p_gyrate(landscape)
    result_b <- lsm_p_gyrate(landscape, cell_center = TRUE)

    expect_true(object = any(result_a$value != result_b$value))
})

test_that("lsm_p_gyrate returns in every column the correct type", {
    expect_type(landscapemetrics_patch_landscape_value$layer, "integer")
    expect_type(landscapemetrics_patch_landscape_value$level, "character")
    expect_type(landscapemetrics_patch_landscape_value$class, "integer")
    expect_type(landscapemetrics_patch_landscape_value$id, "integer")
    expect_type(landscapemetrics_patch_landscape_value$metric, "character")
    expect_type(landscapemetrics_patch_landscape_value$value, "double")
})

# https://fragstats.org/index.php/fragstats-metrics/area-and-edge-metrics/p3-radius-of-gyration
# GYRATE = 0 when the patch consists of a single cell and increases without limit as the patch increases in extent

test_that("lsm_p_frac equals FRAGSTATS", {
    lsm_landscape <- calculate_lsm(landscape, what = c("lsm_p_area", "lsm_p_gyrate")) |>
        tidyr::pivot_wider(names_from = metric, values_from = value) |>
        dplyr::filter(area != min(area)) |>
        dplyr::pull(gyrate)

    lsm_augusta <- calculate_lsm(augusta_nlcd, what = c("lsm_p_area", "lsm_p_gyrate")) |>
        tidyr::pivot_wider(names_from = metric, values_from = value) |>
        dplyr::filter(area != min(area)) |>
        dplyr::pull(gyrate)

    fs_landscape <- dplyr::filter(fragstats_patch, LID == "landscape", metric %in% c("area", "gyrate")) |>
        tidyr::pivot_wider(names_from = metric, values_from = value) |>
        dplyr::filter(area != min(area)) |>
        dplyr::pull(gyrate)

    fs_augusta <- dplyr::filter(fragstats_patch, LID == "augusta_nlcd", metric %in% c("area", "gyrate")) |>
        tidyr::pivot_wider(names_from = metric, values_from = value) |>
        dplyr::filter(area != min(area)) |>
        dplyr::pull(gyrate)

    expect_true(test_correlation(obs = lsm_landscape, exp = fs_landscape, tolerance = tol_cor))
    expect_true(test_correlation(obs = lsm_augusta, exp = fs_augusta, tolerance = tol_cor))
})