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https://github.com/lddl/ch
Contraction Hierarchies (with bidirectional version of Dijkstra's algorithm) technique for computing shortest path in graph.
https://github.com/lddl/ch
breadth-first-search contraction-hierarchies dijkstra dijkstra-algorithm graph hacktoberfest hacktoberfest-accepted hactoberfest2022 isochrone-map isochrones osm pathfinding shortest-path-algorithm shortest-paths turn-restrictions
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Contraction Hierarchies (with bidirectional version of Dijkstra's algorithm) technique for computing shortest path in graph.
- Host: GitHub
- URL: https://github.com/lddl/ch
- Owner: LdDl
- License: apache-2.0
- Created: 2019-05-24T09:55:33.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2023-12-07T00:06:00.000Z (about 1 year ago)
- Last Synced: 2024-10-22T12:27:43.338Z (2 months ago)
- Topics: breadth-first-search, contraction-hierarchies, dijkstra, dijkstra-algorithm, graph, hacktoberfest, hacktoberfest-accepted, hactoberfest2022, isochrone-map, isochrones, osm, pathfinding, shortest-path-algorithm, shortest-paths, turn-restrictions
- Language: Go
- Homepage:
- Size: 105 MB
- Stars: 47
- Watchers: 6
- Forks: 5
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Roadmap: ROADMAP.md
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README
[](https://godoc.org/github.com/LdDl/ch)
[](https://travis-ci.com/LdDl/ch)
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[](https://github.com/LdDl/ch/releases)
# ch - Contraction Hierarchies
## Contraction Hierarchies - technique for speed up of computing shortest path in graph.
This library provides [Contraction Hierarchies](https://en.wikipedia.org/wiki/Contraction_hierarchies) preprocessing graph technique for [Dijkstra's algorithm](https://en.wikipedia.org/wiki/Dijkstra%27s_algorithm). Classic implementation of Dijkstra's algorithm, maneuver restrictions extension and [isochrones](https://en.wikipedia.org/wiki/Isochrone_map) estimation are included also.
## Table of Contents
- [About](#about)
- [Installation](#installation)
- [Go get](#go-get)
- [Go mod](#go-mod)
- [Usage](#usage)
- [Benchmark](#benchmark)
- [Support](#support)
- [ToDo](#todo)
- [Thanks](#thanks)
- [Theory](#theory)
- [Dependencies](#dependencies)
- [License](#license)
## About
This package provides implemented next techniques and algorithms:
* Dijkstra's algorithm
* Contraction hierarchies
* Bidirectional extension of Dijkstra's algorithm with contracted nodes
## Installation
### Go get
```go
go get github.com/LdDl/ch
```
### Go mod
In your project folder execute next command (assuming you have GO111MODULE=on):
```go
go mod init mod
```
Then import library into your code:
```go
package main
import "github.com/LdDl/ch"
func main() {
x := ch.Graph{}
_ = x
}
```
and build
```go
go build
```
You will see next output:
```shell
go: finding github.com/LdDl/ch v1.4.6
go: downloading github.com/LdDl/ch v1.4.6
```
And then you are good to go
## Usage
* Shortest path
Please see this [test file](bidirectional_ch_test.go#L17)
I hope it's pretty clear, but here is little explanation:
```go
g := Graph{} // Prepare variable for storing graph
graphFromCSV(&g, "data/pgrouting_osm.csv") // Import CSV-file file into programm
g.PrepareContractionHierarchies() // Compute contraction hierarchies
u := 144031 // Define source vertex
v := 452090 // Define target vertex
ans, path := g.ShortestPath(u, v) // Get shortest path and it's cost between source and target vertex
```
* Isochrones
Please see this [test file](isochrones_test.go#L7)
```go
g := Graph{} // Prepare variable for storing graph
// ...
// Fill graph with data (vertices and edges)
// ...
isochrones, err := graph.Isochrones(sourceVertex, maxCost) // Evaluate isochrones via bread-first search
if err != nil {
t.Error(err)
return
}
```
### If you want to import OSM (Open Street Map) file then follow instructions for [osm2ch](https://github.com/LdDl/osm2ch#osm2ch)
## Benchmark
You can check benchmarks [here](https://github.com/LdDl/ch/blob/master/BENCHMARK.md)
## Support
If you have troubles or questions please [open an issue](https://github.com/LdDl/ch/issues/new).
## ToDo
Please see [ROADMAP.md](ROADMAP.md)
## Theory
[Dijkstra's algorithm](https://en.wikipedia.org/wiki/Dijkstra%27s_algorithm)
[Bidirectional search](https://en.wikipedia.org/wiki/Bidirectional_search)
[Bidirectional Dijkstra's algorithm's stop condition](http://www.cs.princeton.edu/courses/archive/spr06/cos423/Handouts/EPP%20shortest%20path%20algorithms.pdf)
[Contraction hierarchies](https://en.wikipedia.org/wiki/Contraction_hierarchies)
[Video Lectures](https://ad-wiki.informatik.uni-freiburg.de/teaching/EfficientRoutePlanningSS2012)
## Thanks
Thanks to [this visual explanation](https://jlazarsfeld.github.io/ch.150.project/contents/)
Thanks to [this](https://github.com/navjindervirdee/Advanced-Shortest-Paths-Algorithms) Java implementation of mentioned algorithms
## Dependencies
Thanks to [paulmach](https://github.com/paulmach) for his [OSM-parser](https://github.com/paulmach/osm) written in Go.
Paulmach's license is [here](https://github.com/paulmach/osm/blob/master/LICENSE.md) (it's MIT)
## License
You can check it [here](https://github.com/LdDl/ch/blob/master/LICENSE)
[osm2ch]: (https://github.com/LdDl/osm2ch#osm2ch)
[open an issue]: (https://github.com/LdDl/ch/issues/new)
[BENCHMARK.md]: (https://github.com/LdDl/ch/blob/master/BENCHMARK.md)