Function layers

pub fn layers<G>(
    graph: G,
    first_layer: Vec<G::NodeId>,
) -> impl Iterator<Item = Result<Vec<G::NodeId>, LayersError>>
where
    G: NodeIndexable + IntoNodeIdentifiers + IntoNeighborsDirected + IntoEdgesDirected,
    <G as GraphBase>::NodeId: Debug + Copy + Eq + Hash,

Return an iterator of graph layers

A layer is a subgraph whose nodes are disjoint, i.e., a layer has depth 1. The layers are constructed using a greedy algorithm.

Arguments:

• graph - The graph to get the layers from
• first_layer - A list of node ids for the first layer. This will be the first layer in the output

Will panic! if a provided node is not in the graph.

use rustworkx_core::petgraph::prelude::*;
use rustworkx_core::dag_algo::layers;
use rustworkx_core::dictmap::*;

let edge_list = vec![
 (0, 1),
 (1, 2),
 (2, 3),
 (3, 4),
];

let graph = DiGraph::<u32, u32>::from_edges(&edge_list);
let layers: Vec<Vec<NodeIndex>> = layers(&graph, vec![0.into(),]).map(|layer| layer.unwrap()).collect();
let expected_layers: Vec<Vec<NodeIndex>> = vec![
    vec![0.into(),],
    vec![1.into(),],
    vec![2.into(),],
    vec![3.into(),],
    vec![4.into()]
];
assert_eq!(layers, expected_layers)