Struct GraphBuilder

Source

pub struct GraphBuilder { /* private fields */ }

Expand description

A fluent builder for constructing Graph instances.

GraphBuilder accumulates vertices and edges, then produces a Graph in a single build() call. It validates structure only at build time, so intermediate states need not be valid graphs.

§Examples

use rust_igraph::GraphBuilder;

// Build a directed triangle.
let g = GraphBuilder::directed()
    .vertices(3)
    .edge(0, 1)
    .edge(1, 2)
    .edge(2, 0)
    .build()
    .unwrap();
assert_eq!(g.vcount(), 3);
assert_eq!(g.ecount(), 3);
assert!(g.is_directed());

use rust_igraph::GraphBuilder;

// Build from an edge list (vertex count inferred).
let g = GraphBuilder::undirected()
    .edges(&[(0, 1), (1, 2), (2, 3), (3, 0)])
    .build()
    .unwrap();
assert_eq!(g.vcount(), 4);
assert_eq!(g.ecount(), 4);

Implementations§

Source §

impl GraphBuilder

Source

pub fn directed() -> Self

Start building a directed graph.

§Examples

use rust_igraph::GraphBuilder;

let g = GraphBuilder::directed()
    .vertices(2)
    .edge(0, 1)
    .build()
    .unwrap();
assert!(g.is_directed());

Source

pub fn undirected() -> Self

Start building an undirected graph.

§Examples

use rust_igraph::GraphBuilder;

let g = GraphBuilder::undirected()
    .vertices(5)
    .build()
    .unwrap();
assert!(!g.is_directed());
assert_eq!(g.vcount(), 5);

Source

pub fn vertices(self, n: u32) -> Self

Set the vertex count explicitly.

If not called, vertex count is inferred from the maximum vertex id in any added edge (plus one). Calling this with a value smaller than the inferred count causes build() to return an error.

Source

pub fn edge(self, from: VertexId, to: VertexId) -> Self

Add a single edge.

§Examples

use rust_igraph::GraphBuilder;

let g = GraphBuilder::undirected()
    .edge(0, 1)
    .edge(1, 2)
    .build()
    .unwrap();
assert_eq!(g.ecount(), 2);

Source

pub fn edges(self, pairs: &[(VertexId, VertexId)]) -> Self

Add multiple edges from a slice of (from, to) pairs.

§Examples

use rust_igraph::GraphBuilder;

let g = GraphBuilder::undirected()
    .edges(&[(0, 1), (1, 2), (2, 0)])
    .build()
    .unwrap();
assert_eq!(g.ecount(), 3);

Source

pub fn path(self, vertices: &[VertexId]) -> Self

Add a chain of edges forming a path: v0 -> v1 -> v2 -> ... -> vk.

§Examples

use rust_igraph::GraphBuilder;

let g = GraphBuilder::undirected()
    .path(&[0, 1, 2, 3, 4])
    .build()
    .unwrap();
assert_eq!(g.ecount(), 4);

Source

pub fn cycle(self, vertices: &[VertexId]) -> Self

Add edges forming a cycle: v0 -> v1 -> ... -> vk -> v0.

§Examples

use rust_igraph::GraphBuilder;

let g = GraphBuilder::undirected()
    .cycle(&[0, 1, 2, 3])
    .build()
    .unwrap();
assert_eq!(g.ecount(), 4);
assert!(g.has_edge(3, 0));

Source

pub fn clique(self, vertices: &[VertexId]) -> Self

Add edges forming a complete subgraph (clique) on the given vertices.

§Examples

use rust_igraph::GraphBuilder;

let g = GraphBuilder::undirected()
    .clique(&[0, 1, 2, 3])
    .build()
    .unwrap();
// K_4 has 4*3/2 = 6 edges.
assert_eq!(g.ecount(), 6);

Source

pub fn star(self, center: VertexId, leaves: &[VertexId]) -> Self

Add edges connecting a center vertex to all given leaf vertices (star).

§Examples

use rust_igraph::GraphBuilder;

let g = GraphBuilder::undirected()
    .star(0, &[1, 2, 3, 4])
    .build()
    .unwrap();
assert_eq!(g.ecount(), 4);

Source

pub fn build(self) -> IgraphResult<Graph>

Consume the builder and produce a Graph.

§Errors

Returns an error if the explicit vertex count is smaller than required by the edges.

§Examples

use rust_igraph::GraphBuilder;

// Error: vertex count too small for edge (0, 5).
let r = GraphBuilder::undirected()
    .vertices(3)
    .edge(0, 5)
    .build();
assert!(r.is_err());