use std::{fs, path::PathBuf};
use ndarray::Array2;
use rand::{SeedableRng, rngs::StdRng};
use serde::Deserialize;
use rscopulas::{
CopulaModel, EvalOptions, PairCopulaFamily, PairCopulaParams, PairCopulaSpec, PseudoObs,
Rotation, SampleOptions, VineCopula, VineEdge, VineFitOptions, VineStructureKind, VineTree,
};
#[derive(Debug, Deserialize)]
struct Metadata {
source_package: String,
source_version: String,
}
#[derive(Debug, Deserialize)]
struct EdgeFixture {
conditioned: [usize; 2],
conditioning: Vec<usize>,
family: String,
rotation: String,
params: Vec<f64>,
}
#[derive(Debug, Deserialize)]
struct TreeFixture {
level: usize,
edges: Vec<EdgeFixture>,
}
#[derive(Debug, Deserialize)]
struct VineLogPdfFixture {
metadata: Metadata,
structure: String,
truncation_level: Option<usize>,
matrix: Vec<Vec<usize>>,
trees: Vec<TreeFixture>,
inputs: Vec<Vec<f64>>,
expected_log_pdf: Vec<f64>,
}
#[derive(Debug, Deserialize)]
struct VineSampleSummaryFixture {
metadata: Metadata,
structure: String,
truncation_level: Option<usize>,
matrix: Vec<Vec<usize>>,
trees: Vec<TreeFixture>,
seed: u64,
sample_size: usize,
expected_mean: Vec<f64>,
expected_kendall_tau: Vec<Vec<f64>>,
}
#[derive(Debug, Deserialize)]
struct VineFitDataFixture {
metadata: Metadata,
structure: String,
trees: Vec<TreeFixture>,
data: Vec<Vec<f64>>,
}
#[test]
fn mixed_r_vine_matches_vinecopula_log_pdf_fixture() {
let fixture: VineLogPdfFixture = load_fixture("mixed_r_vine_log_pdf_d5_case01.json");
assert_eq!(fixture.metadata.source_package, "VineCopula");
assert_eq!(fixture.structure, "R");
let model = build_model(&fixture.trees, fixture.truncation_level);
assert_eq!(model.structure(), VineStructureKind::R);
assert_eq!(model.structure_info().matrix, array2_usize(&fixture.matrix));
let input =
PseudoObs::new(array2_f64(&fixture.inputs)).expect("fixture inputs should be valid");
let actual = model
.log_pdf(&input, &EvalOptions::default())
.expect("log pdf should evaluate");
for (idx, (left, right)) in actual
.iter()
.zip(fixture.expected_log_pdf.iter())
.enumerate()
{
assert!(
(left - right).abs() < 1e-8,
"fixture {} mismatch at row {idx}: left={left}, right={right}",
fixture.metadata.source_version
);
}
}
#[test]
fn mixed_r_vine_sample_statistics_match_vinecopula_fixture() {
let fixture: VineSampleSummaryFixture =
load_fixture("mixed_r_vine_sample_summary_d5_case01.json");
assert_eq!(fixture.metadata.source_package, "VineCopula");
assert_eq!(fixture.structure, "R");
let model = build_model(&fixture.trees, fixture.truncation_level);
assert_eq!(model.structure_info().matrix, array2_usize(&fixture.matrix));
let mut rng = StdRng::seed_from_u64(fixture.seed);
let samples = model
.sample(fixture.sample_size, &mut rng, &SampleOptions::default())
.expect("sampling should succeed");
let sample_obs = PseudoObs::new(samples).expect("sample should be valid");
let means = column_means(&sample_obs);
let tau = rscopulas::stats::kendall_tau_matrix(&sample_obs);
for (idx, (actual, expected)) in means.iter().zip(fixture.expected_mean.iter()).enumerate() {
assert!(
(actual - expected).abs() < 1.5e-2,
"mean mismatch at column {idx}: left={actual}, right={expected}"
);
}
for row in 0..tau.nrows() {
for col in 0..tau.ncols() {
let expected = fixture.expected_kendall_tau[row][col];
assert!((tau[(row, col)] - expected).abs() < 2.5e-2);
}
}
}
#[test]
fn mixed_r_vine_serde_round_trip_preserves_log_pdf_and_sampling() {
let log_pdf_fixture: VineLogPdfFixture = load_fixture("mixed_r_vine_log_pdf_d5_case01.json");
let sample_fixture: VineSampleSummaryFixture =
load_fixture("mixed_r_vine_sample_summary_d5_case01.json");
let model = build_model(&log_pdf_fixture.trees, log_pdf_fixture.truncation_level);
let input = PseudoObs::new(array2_f64(&log_pdf_fixture.inputs))
.expect("fixture inputs should be valid");
let encoded = serde_json::to_vec(&model).expect("vine model should serialize");
let restored: VineCopula =
serde_json::from_slice(&encoded).expect("vine model should deserialize");
assert_eq!(
restored.structure_info().matrix,
model.structure_info().matrix
);
let original_log_pdf = model
.log_pdf(&input, &EvalOptions::default())
.expect("original log pdf should evaluate");
let restored_log_pdf = restored
.log_pdf(&input, &EvalOptions::default())
.expect("restored log pdf should evaluate");
assert_eq!(original_log_pdf, restored_log_pdf);
let mut original_rng = StdRng::seed_from_u64(sample_fixture.seed);
let mut restored_rng = StdRng::seed_from_u64(sample_fixture.seed);
let original_samples = model
.sample(256, &mut original_rng, &SampleOptions::default())
.expect("original sampling should succeed");
let restored_samples = restored
.sample(256, &mut restored_rng, &SampleOptions::default())
.expect("restored sampling should succeed");
assert_eq!(original_samples, restored_samples);
}
#[test]
fn fit_r_vine_is_not_a_relabel_of_canonical_vines_on_mixed_reference_data() {
let fixture: VineFitDataFixture = load_fixture("mixed_r_vine_fit_data_d5_case01.json");
assert_eq!(fixture.metadata.source_package, "VineCopula");
assert_eq!(fixture.structure, "R");
assert_eq!(fixture.trees.len(), 4);
let data = PseudoObs::new(array2_f64(&fixture.data)).expect("fixture data should be valid");
let options = VineFitOptions {
family_set: vec![
PairCopulaFamily::Independence,
PairCopulaFamily::Gaussian,
PairCopulaFamily::Clayton,
PairCopulaFamily::Frank,
PairCopulaFamily::Gumbel,
],
truncation_level: Some(2),
..VineFitOptions::default()
};
let reference_trees = fixture
.trees
.iter()
.take(
options
.truncation_level
.expect("truncation level should be set"),
)
.map(tree_signature)
.collect::<Vec<_>>();
let r_fit = VineCopula::fit_r_vine(&data, &options).expect("R-vine fit should succeed");
let c_fit = VineCopula::fit_c_vine(&data, &options).expect("C-vine fit should succeed");
let d_fit = VineCopula::fit_d_vine(&data, &options).expect("D-vine fit should succeed");
assert_eq!(r_fit.model.structure(), VineStructureKind::R);
let fitted_trees = r_fit
.model
.trees()
.iter()
.map(tree_signature)
.collect::<Vec<_>>();
let shared_first_tree = fitted_trees[0]
.iter()
.filter(|edge| reference_trees[0].contains(*edge))
.count();
assert!(
shared_first_tree >= 2,
"fitted R-vine should recover at least two fixture first-tree edges; fitted={:?}, reference={:?}",
fitted_trees[0],
reference_trees[0]
);
assert!(
fitted_trees[0].contains(&((2, 4), Vec::new())),
"fitted R-vine should recover the fixture's strongest cross-branch edge"
);
assert!(
r_fit
.model
.trees()
.iter()
.flat_map(|tree| tree.edges.iter())
.any(|edge| !edge.conditioning.is_empty()),
"fitted R-vine should contain higher-tree conditioned edges"
);
let canonical_best = c_fit.diagnostics.loglik.max(d_fit.diagnostics.loglik);
assert!(
(r_fit.diagnostics.loglik - canonical_best).abs() > 1e-6,
"R-vine fit should not be a relabeled best-of-C/D fit: r={}, c={}, d={}",
r_fit.diagnostics.loglik,
c_fit.diagnostics.loglik,
d_fit.diagnostics.loglik
);
}
fn build_model(trees: &[TreeFixture], truncation_level: Option<usize>) -> VineCopula {
let trees = trees
.iter()
.map(|tree| VineTree {
level: tree.level,
edges: tree
.edges
.iter()
.map(|edge| VineEdge {
tree: tree.level,
conditioned: (edge.conditioned[0], edge.conditioned[1]),
conditioning: edge.conditioning.clone(),
copula: PairCopulaSpec {
family: parse_family(&edge.family),
rotation: parse_rotation(&edge.rotation),
params: parse_params(&edge.params),
},
})
.collect(),
})
.collect::<Vec<_>>();
VineCopula::from_trees(VineStructureKind::R, trees, truncation_level)
.expect("fixture trees should form a valid vine")
}
fn parse_family(value: &str) -> PairCopulaFamily {
match value {
"Independence" => PairCopulaFamily::Independence,
"Gaussian" => PairCopulaFamily::Gaussian,
"StudentT" => PairCopulaFamily::StudentT,
"Clayton" => PairCopulaFamily::Clayton,
"Frank" => PairCopulaFamily::Frank,
"Gumbel" => PairCopulaFamily::Gumbel,
other => panic!("unexpected family {other}"),
}
}
fn parse_rotation(value: &str) -> Rotation {
match value {
"R0" => Rotation::R0,
"R90" => Rotation::R90,
"R180" => Rotation::R180,
"R270" => Rotation::R270,
other => panic!("unexpected rotation {other}"),
}
}
fn parse_params(values: &[f64]) -> PairCopulaParams {
match values {
[] => PairCopulaParams::None,
[value] => PairCopulaParams::One(*value),
[first, second] => PairCopulaParams::Two(*first, *second),
_ => panic!("unexpected parameter arity"),
}
}
fn fixture_dir() -> PathBuf {
PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("../../fixtures/reference/vinecopula/v2")
}
fn load_fixture<T: for<'de> Deserialize<'de>>(name: &str) -> T {
let path = fixture_dir().join(name);
let bytes = fs::read(path).expect("fixture should exist");
serde_json::from_slice(&bytes).expect("fixture should deserialize")
}
fn array2_f64(rows: &[Vec<f64>]) -> Array2<f64> {
let nrows = rows.len();
let ncols = rows.first().map_or(0, Vec::len);
let data = rows
.iter()
.flat_map(|row| row.iter().copied())
.collect::<Vec<_>>();
Array2::from_shape_vec((nrows, ncols), data).expect("rows should form a matrix")
}
fn array2_usize(rows: &[Vec<usize>]) -> Array2<usize> {
let nrows = rows.len();
let ncols = rows.first().map_or(0, Vec::len);
let data = rows
.iter()
.flat_map(|row| row.iter().copied())
.collect::<Vec<_>>();
Array2::from_shape_vec((nrows, ncols), data).expect("rows should form a matrix")
}
fn column_means(data: &PseudoObs) -> Vec<f64> {
(0..data.dim())
.map(|col| data.as_view().column(col).iter().sum::<f64>() / data.n_obs() as f64)
.collect()
}
fn tree_signature<T>(tree: &T) -> Vec<((usize, usize), Vec<usize>)>
where
T: TreeLike,
{
let mut edges = tree
.edges()
.iter()
.map(|edge| {
let conditioned = if edge.conditioned().0 < edge.conditioned().1 {
edge.conditioned()
} else {
(edge.conditioned().1, edge.conditioned().0)
};
(conditioned, edge.conditioning().to_vec())
})
.collect::<Vec<_>>();
edges.sort();
edges
}
trait TreeLike {
type Edge: EdgeLike;
fn edges(&self) -> &[Self::Edge];
}
trait EdgeLike {
fn conditioned(&self) -> (usize, usize);
fn conditioning(&self) -> &[usize];
}
impl TreeLike for TreeFixture {
type Edge = EdgeFixture;
fn edges(&self) -> &[Self::Edge] {
&self.edges
}
}
impl TreeLike for VineTree {
type Edge = VineEdge;
fn edges(&self) -> &[Self::Edge] {
&self.edges
}
}
impl EdgeLike for EdgeFixture {
fn conditioned(&self) -> (usize, usize) {
(self.conditioned[0], self.conditioned[1])
}
fn conditioning(&self) -> &[usize] {
&self.conditioning
}
}
impl EdgeLike for VineEdge {
fn conditioned(&self) -> (usize, usize) {
self.conditioned
}
fn conditioning(&self) -> &[usize] {
&self.conditioning
}
}