https://github.com/postlagerkarte/geohash-dotnet
Easy-to-use and feature-rich geohash library written in C# | Encode & Decode of Geohashes | Converts a polygon into a set of geohashes with arbitrary precision | Allows Geohash Compression
https://github.com/postlagerkarte/geohash-dotnet
csharp geohash geohash-algorithm geohash-library longitude-and-latitude polygon
Last synced: 4 months ago
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Easy-to-use and feature-rich geohash library written in C# | Encode & Decode of Geohashes | Converts a polygon into a set of geohashes with arbitrary precision | Allows Geohash Compression
- Host: GitHub
- URL: https://github.com/postlagerkarte/geohash-dotnet
- Owner: Postlagerkarte
- License: mit
- Created: 2019-07-12T14:23:01.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2024-12-11T21:03:03.000Z (11 months ago)
- Last Synced: 2025-04-12T04:47:40.294Z (7 months ago)
- Topics: csharp, geohash, geohash-algorithm, geohash-library, longitude-and-latitude, polygon
- Language: C#
- Homepage:
- Size: 1.66 MB
- Stars: 87
- Watchers: 1
- Forks: 8
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# geohash-dotnet 
An easy-to-use, feature-rich geohash library for .NET
## Installation
Install via NuGet Package Manager:
```
Install-Package geohash-dotnet
```
[](https://www.nuget.org/packages/geohash-dotnet) [](https://www.nuget.org/packages/geohash-dotnet)
## Features
### Geohasher
- Encode/Decode: Convert between geographic coordinates and geohash strings.
- Neighbors: Find adjacent geohashes in all cardinal directions.
- Subhashes: Retrieve finer-grained geohashes within a parent geohash.
- Parent Geohash: Get the less precise parent of a given geohash.
- Bounding Box: Obtain the geographic bounding box of a geohash.
### PolygonHasher
- Generate geohashes within a specified polygon based on precision and inclusion criteria.
- Ideal for spatial indexing and geospatial queries within complex areas.
### GeohashCompressor
- Compresses a set of geohashes to a minimal set that still covers the same area.
- Optimizes storage and improves performance for spatial queries.
## Geohasher
Generate geohashes that cover a specific polygon:
```csharp
// Create a new Geohasher instance
var geohasher = new Geohasher();
// Encode latitude and longitude into a geohash string
string geohash = geohasher.Encode(37.4219999, -122.0840575, 9);
// Decode the geohash back to latitude and longitude
(double latitude, double longitude) = geohasher.Decode(geohash);
// Get subhashes of a geohash
string[] subhashes = geohasher.GetSubhashes(geohash);
// Get neighbors of a geohash
Dictionary neighbors = geohasher.GetNeighbors(geohash);
// Get parent of a geohash
string parent = geohasher.GetParent(geohash);
// Get the bounding box of a geohash
BoundingBox bbox = geohasher.GetBoundingBox(geohash);
```
## PolygonHasher
```csharp
// Initialize PolygonHasher
var polygonHasher = new PolygonHasher();
// Define a polygon
Polygon polygon = new Polygon(new LinearRing(new Coordinate[] {
new Coordinate(-122.4183, 37.7755),
new Coordinate(-122.4183, 37.7814),
new Coordinate(-122.4085, 37.7814),
new Coordinate(-122.4085, 37.7755),
new Coordinate(-122.4183, 37.7755) // Closing the ring
}));
// Get geohashes of precision 6 that intersect with the polygon
var geohashes = polygonHasher.GetHashes(polygon, 6, PolygonHasher.GeohashInclusionCriteria.Intersects);
// Output the geohashes
foreach (string hash in geohashes)
{
Console.WriteLine(hash);
}
```
## GeohashCompressor
Compress a list of geohashes into a minimal covering set:
```csharp
// Initialize GeohashCompressor
var compressor = new GeohashCompressor();
// Define input geohashes
var inputGeohashes = new[] {
"tdnu20", "tdnu21", "tdnu22", "tdnu23", "tdnu24", "tdnu25",
"tdnu26", "tdnu27", "tdnu28", "tdnu29", "tdnu2b", "tdnu2c",
// ... additional geohashes
};
// Compress the geohashes
var compressedGeohashes = compressor.Compress(inputGeohashes);
// Output the compressed geohashes
foreach (var hash in compressedGeohashes)
{
Console.WriteLine(hash);
}
```
### Finding Neighbors
```csharp
Dictionary neighbors = geohasher.GetNeighbors(geohash);
```
```csharp
string northNeighbor = neighbors[Direction.North];
string southNeighbor = neighbors[Direction.South];
// ... and so on for the other directions
```
find the neighbor hash in a specific direction, use the GetNeighbor() method:
```csharp
string northNeighbor = geohasher.GetNeighbor(geohash, Direction.North);
```
### Subhashes
Subhashes represent smaller, equally-sized regions within a geohash's bounding box:
```csharp
string[] subhashes = geohasher.GetSubhashes(geohash);
```
### Parent Geohash
The parent of a geohash is the geohash that covers the same area but at a lower precision level:
```csharp
string parent = geohasher.GetParent(geohash);
```
Keep in mind that the parent geohash will be less precise and cover a larger area.
### Bounding Box
To obtain the bounding box (minimum and maximum latitude and longitude):
```csharp
BoundingBox bbox = geohasher.GetBoundingBox(geohash);
```
### Performance Notes
PolygonHasher and GeohashCompressor have a time complexity of O(N²) relative to the number of geohashes processed.