https://github.com/bertt/geoparquet
.NET 8 Reader/Writer library for GeoParquet files.
https://github.com/bertt/geoparquet
geoparquet
Last synced: 5 months ago
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.NET 8 Reader/Writer library for GeoParquet files.
- Host: GitHub
- URL: https://github.com/bertt/geoparquet
- Owner: bertt
- License: mit
- Created: 2022-12-23T10:30:25.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2025-11-04T20:52:23.000Z (8 months ago)
- Last Synced: 2025-11-04T21:19:09.602Z (8 months ago)
- Topics: geoparquet
- Language: C#
- Homepage:
- Size: 19.4 MB
- Stars: 20
- Watchers: 1
- Forks: 4
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# GeoParquet
[](https://www.nuget.org/packages/bertt.geoparquet)
.NET 8 Reader/Writer library for GeoParquet files.
https://geoparquet.org/
Specification: https://github.com/opengeospatial/geoparquet/blob/main/format-specs/geoparquet.md
Schema: https://github.com/opengeospatial/geoparquet/blob/main/format-specs/schema.json
Blog: https://bertt.wordpress.com/2022/12/20/geoparquet-geospatial-vector-data-using-apache-parquet/
NuGet: https://www.nuget.org/packages/bertt.geoparquet/
Sample GeoParquet JSON metadata:
```json
{
"version":"1.0.0",
"primary_column":"geometry",
"columns":{
"geometry":{
"encoding":"WKB",
"geometry_types":[
"MultiPolygon"
],
"bbox":[
3.358378252510583,
50.750367484598314,
7.227498450845831,
53.55501451790761
]
}
}
}
```
## Architecture
In this package there are functions for handling Geometadata:
1] Reading
For reading GeoParquet files there is a ParquetFileReader extension method GetGeoMetadata() to obtain the Geo metadata
2] Writing
For writing GeoParquet files there is GeoMetadata.GetGeoMetadata(GeoColumn geoColumn) static function to get the geo metadata dictionary. This
dictionary can be passed to the ParquetFileWriter constructor.
See sample code below for reading/writing samples.
## geoparquet-tools
In development: geoparquet-tools, a command line tool for inspecting GeoParquet files.
See releases for first version, build for Linux, Mac, Windows
Install
```
$ wget https://github.com/bertt/geoparquet/releases/download/0.1/geoparquet-tools-linux-x64.tar.gz
$ tar -xf geoparquet-tools-linux-x64.tar.gz
$ ./geoparquet-tools
```
Options:
```
-i : inspect GeoParquet file
-h : help
```
## Sample code
In these samples NetTopologySuite (https://github.com/NetTopologySuite/NetTopologySuite) is used for handling geometries, but any library that can handle
WKB geometries can be used.
### Reading
Use extension method 'parquetReader.GetGeoMetadata()':
```
var file = "testfixtures/gemeenten2016_1.0.parquet";
var file1 = new ParquetFileReader(file);
var geoParquet = file1.GetGeoMetadata();
Assert.That(geoParquet.Version == "1.0.0");
var rowGroupReader = file1.RowGroup(0);
var gemName = rowGroupReader.Column(33).LogicalReader().First();
Assert.IsTrue(gemName == "Appingedam");
var geometryWkb = rowGroupReader.Column(17).LogicalReader().First();
var wkbReader = new WKBReader();
var multiPolygon = (MultiPolygon)wkbReader.Read(geometryWkb);
Assert.That(multiPolygon.Coordinates.Count() == 165);
var firstCoordinate = multiPolygon.Coordinates.First();
Assert.That(firstCoordinate.CoordinateValue.X == 6.8319922331647964);
Assert.That(firstCoordinate.CoordinateValue.Y == 53.327288101088072);
```
Sample reading GeoParquet file with GeoArrow encoding:
```
var geomColumnId = GetColumnId(rowGroupReader, "xy");
Assert.That(geoParquet.Columns.First().Value.Encoding == "geoarrow.multipolygon");
if (geomColumnId != null)
{
var geometryArrow = rowGroupReader.Column((int)geomColumnId).LogicalReader().First();
Assert.That(geometryArrow.Length == 1);
Assert.That(geometryArrow[0].Length == 1);
Assert.That(geometryArrow[0][0].Length == 165); //165 vertices
Assert.That(geometryArrow[0][0][0].Length == 2); //2 points
Assert.That(geometryArrow[0][0][0][0] == 6.8319922331647964); // longitude first vertice
Assert.That(geometryArrow[0][0][0][1] == 53.327288101088072); // latitude first vertice
}
```
### Writing
Use GeoMetadata.GetGeoMetadata to construct the ParquetFileWriter, store the geometries as WKB.
Result Parquet file can be visualized in QGIS:
```
var columns = new Column[]
{
new Column("city"),
new Column("geometry")
};
var bbox = new double[] { 3.3583782525105832,
50.750367484598314,
7.2274984508458306,
53.555014517907608};
var geoColumn = new GeoColumn();
geoColumn.Bbox = bbox;
geoColumn.Encoding = "WKB";
geoColumn.Geometry_types.Add("Point");
var geometadata = GeoMetadata.GetGeoMetadata(geoColumn);
var parquetFileWriter = new ParquetFileWriter(@"writing_sample.parquet", columns, keyValueMetadata: geometadata);
var rowGroup = parquetFileWriter.AppendRowGroup();
var nameWriter = rowGroup.NextColumn().LogicalWriter();
nameWriter.WriteBatch(new string[] { "London", "Derby" });
var geom0 = new Point(5, 51);
var geom1 = new Point(5.5, 51);
var wkbWriter = new WKBWriter();
var wkbBytes = new byte[][] { wkbWriter.Write(geom0), wkbWriter.Write(geom1) };
var geometryWriter = rowGroup.NextColumn().LogicalWriter();
geometryWriter.WriteBatch(wkbBytes);
parquetFileWriter.Close();
```
### Writing geometries with native encoding
See unit tests.
Suppported encodings:
- Point - MultiPoint
- Line
- Polygon
## Dependencies
- ParquetSharp 21 https://github.com/G-Research/ParquetSharp
# Roadmap
- Add support for multiple geometry columns;
- add writing Apache Arrow encoding for geometries;
- add support for crs;
- add (spatial) filters.
## History
2023-11-26: version 1.0.1 - target .net 6 and 8
2023-11-16: version 1.0 - using schema v1.0.0, ParquetSharp to 13 - to .NET 8
2023-07-13: version 0.5 - using schema v1.0.0-beta.1, ParquetSharp to 12.0.1
2023-01-01: version 0.4 - using ParquetSharp 10.0.1-beta1 instead of Parquet.Net 4
2022-12-30: version 0.3.1 - make geometry column name optional in SetGeoMetadata
2022-12-30: version 0.3 - add extension method to write geo metadata
2022-12-27: version 0.2 - add extension method to read geo metadata
2022-12-23: version 0.1 - implementing reader