Struct CoreDecomposition 

pub struct CoreDecomposition {
    pub core_numbers: Vec<usize>,
    pub shell_index: Vec<usize>,
    pub max_core: usize,
    pub num_nodes: usize,
}

k-core decomposition and k-shell index for undirected graphs.

The k-core of a graph is the maximal subgraph in which every node has degree at least k. The core number (or coreness) of a node is the largest k for which the node belongs to the k-core.

The k-shell consists of nodes with core number exactly k (in the k-core but not in the (k+1)-core).

Algorithm

Iterative degree peeling: repeatedly remove nodes with degree < k, starting from k=1 upwards.

Time complexity

O(m) where m is the number of edges.

Fields

core_numbers: Vec<usize>

Core number (coreness) of each node.

shell_index: Vec<usize>

Shell index = core number (same as core number; kept separately for clarity).

max_core: usize

Maximum core number (degeneracy of the graph).

num_nodes: usize

Number of nodes.

Implementations

impl CoreDecomposition

pub fn compute(adj: &Array2<f64>) -> Self

Compute k-core decomposition from an adjacency matrix.

pub fn k_core_nodes(&self, k: usize) -> Vec<usize>

Return the set of node indices in the k-core (core number >= k).

pub fn k_shell_nodes(&self, k: usize) -> Vec<usize>

Return the set of node indices in the k-shell (core number == k).

pub fn main_core_nodes(&self) -> Vec<usize>

Return the main core (nodes with maximum core number).

pub fn degeneracy_ordering(&self) -> Vec<usize>

Compute the degeneracy ordering (nodes ordered by core number ascending).

pub fn shell_distribution(&self) -> Vec<(usize, usize)>

Compute the coreness distribution: number of nodes at each shell level.

Trait Implementations

impl Clone for CoreDecomposition

fn clone(&self) -> CoreDecomposition

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CoreDecomposition

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.