Function neighbor_sample 

pub fn neighbor_sample(
    graph: &Graph,
    seeds: &[VertexId],
    fan_out: &[usize],
    seed: u64,
) -> IgraphResult<NeighborSampleResult>

Sample k-hop neighborhoods around seed vertices.

For each hop from 1 to fan_out.len(), samples at most fan_out[hop-1] neighbors per frontier vertex. Sampling is uniform without replacement when the number of neighbors exceeds the fan-out; otherwise all neighbors are included.

Parameters

• graph — The input graph.
• seeds — Starting vertices (the “batch”).
• fan_out — Number of neighbors to sample at each hop. Length determines the number of hops.
• seed — PRNG seed for deterministic sampling.

Returns

A NeighborSampleResult with layers and inter-layer edges.

Examples

use rust_igraph::{Graph, neighbor_sample};

// Star graph: center 0 connected to 1,2,3,4
let g = Graph::from_edges(
    &[(0,1),(0,2),(0,3),(0,4)], false, Some(5)
).unwrap();

// 1-hop sampling from vertex 0, fan_out=2
let result = neighbor_sample(&g, &[0], &[2], 42).unwrap();
assert_eq!(result.layers[0], vec![0]);
assert_eq!(result.layers[1].len(), 2); // sampled 2 of 4 neighbors
assert_eq!(result.edges[0].len(), 2);