---
title: "Routes on graphs"
url: https://recursiveai.org/onepath/cookbook/graph-routes/
description: "Find routes on a weighted graph with OnePath, speed up repeated queries with landmarks, and link nearby points into a point graph."
version: "1.1.0"
---

# Routes on graphs

Find routes on a weighted graph with OnePath, speed up repeated queries with landmarks, and link nearby points into a point graph.

```csharp
using RecursiveAI.OnePath;

// A small road network: node ids, and edges with travel times in minutes.
var roads = Graph.From(new[]
{
    new GraphEdge(0, 1, 4.0), new GraphEdge(1, 2, 1.5), new GraphEdge(0, 2, 7.0),
    new GraphEdge(2, 3, 2.0), new GraphEdge(1, 3, 6.0), new GraphEdge(3, 4, 3.0),
});
GraphPath route = roads.FindPath(0, 4);
Console.WriteLine($"0 -> 4: {string.Join(" -> ", route.Nodes.ToArray())}, {route.Cost} minutes");

// Landmarks (ALT) speed up repeated queries on the same graph; the answer is the same.
Landmarks landmarks = roads.BuildLandmarks();
GraphPath fast = roads.FindPath(0, 4, GraphOptions.WithLandmarks(landmarks));
Console.WriteLine($"with landmarks: {string.Join(" -> ", fast.Nodes.ToArray())}, {fast.Cost} minutes");

// A point graph links points closer than MaxDistance.
var points = PointGraph.From(new[] { new Point3(0, 0), new Point3(1, 0), new Point3(2, 0), new Point3(2, 1) },
                             new PointGraphOptions { MaxDistance = 1.1 });
GraphPath walk = points.FindPath(new Point3(0, 0), new Point3(2, 1));
Console.WriteLine($"point graph: {walk.Nodes.Length} nodes, cost {walk.Cost}");
```

```text
0 -> 4: 0 -> 1 -> 2 -> 3 -> 4, 10.5 minutes
with landmarks: 0 -> 1 -> 2 -> 3 -> 4, 10.5 minutes
point graph: 4 nodes, cost 3
```

## Good to know

- **`Graph.From(edges)`** builds a weighted graph from `GraphEdge(from, to, weight)` values, each added in both directions unless you pass `directed: true`. `FindPath` returns `Nodes` and `Cost`; bidirectional search is an option.
- **Landmarks (ALT)** precompute distances to a few nodes once, which tightens the heuristic for every later query on the same graph. The path is the same; the search is shorter on large road networks. `Landmarks` serialize, so you can build them offline.
- **`PointGraph.From(points, options)`** links every pair of points closer than `MaxDistance`, for waypoints, cover points or a coarse network over open terrain.

Graphs, bidirectional search and the landmark format are in [graphs](https://recursiveai.org/onepath/docs/graphs/).