update readme, add license, add st_makeline, st_flipcoordinates, fix nulls not being properly written in st_write

Author: Maxxen

LICENSE

@@ -0,0 +1,7 @@
+Copyright 2018-2023 DuckDB Labs BV
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

@@ -1,5 +1,7 @@
 # DuckDB Spatial Extension
 
+🚧 WORK IN PROGRESS 🚧
+
 **Table of contents**
 - [DuckDB Spatial Extension](#duckdb-spatial-extension)
 - [What is this?](#what-is-this)
@@ -150,14 +152,14 @@ ON ST_Within(st_transform(dropoff_point, 'EPSG:4326', 'ESRI:102718'), end_zone.g
 </details>
 
 We can export the joined table to a GeoJSONSeq file using the GDAL copy function, passing in a GDAL layer creation option. 
-Since GeoJSON only supports a single geometry per feature, we need to use the `ST_Collect` function to combine the pickup and dropoff points into a single multi point geometry.
+Since GeoJSON only supports a single geometry per feature, we can use the `ST_MakeLine` function to combine the pickup and dropoff points into a single line geometry. The default coordinate reference system for GeoJSON is WGS84, but the coordinates are expected to be in longitude/latitude, so we need to flip the geometry using the `ST_FlipCoordinates` function.
 
 ```sql
 COPY (
     SELECT 
-        ST_AsWKB(ST_Collect([pickup_point, dropoff_point])) as wkb_geometry,
-        start_zone, 
-        end_zone, 
+        ST_AsWKB(ST_FlipCoordinates(ST_MakeLine(pickup_point, dropoff_point))) as wkb_geometry,
+        start_zone,
+        end_zone,
         time::VARCHAR as trip_time 
     FROM joined) 
 TO 'joined.geojsonseq' 
@@ -169,16 +171,16 @@ WITH (FORMAT GDAL, DRIVER 'GeoJSONSeq', LAYER_CREATION_OPTIONS 'WRITE_BBOX=YES')
 </summary>
 
 ```json
-{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:52:00" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 40.643515, -73.789923 ], [ 40.680395, -73.97608 ] ] } }
-{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:35:00" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 40.645422, -73.776445 ], [ 40.670782, -73.98427 ] ] } }
-{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:45:42" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 40.645065, -73.776878 ], [ 40.662571, -73.992153 ] ] } }
-{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:36:00" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 40.641508, -73.788028 ], [ 40.670927, -73.97584 ] ] } }
-{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:47:58" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 40.644749, -73.781855 ], [ 40.663663, -73.980129 ] ] } }
-{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:32:10" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 40.641559, -73.787494 ], [ 40.673479, -73.974694 ] ] } }
-{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:36:59" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 40.643342, -73.790138 ], [ 40.662379, -73.982721 ] ] } }
-{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:32:00" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 40.641248, -73.786952 ], [ 40.676237, -73.97421 ] ] } }
-{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:33:21" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 40.648514, -73.783892 ], [ 40.669721, -73.979283 ] ] } }
-{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:35:45" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 40.645272, -73.776643 ], [ 40.66723, -73.978873 ] ] } }
+{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:52:00" }, "geometry": { "type": "LineString", "coordinates": [ [ -73.789923, 40.643515 ], [ -73.97608, 40.680395 ] ] } }
+{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:35:00" }, "geometry": { "type": "LineString", "coordinates": [ [ -73.776445, 40.645422 ], [ -73.98427, 40.670782 ] ] } }
+{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:45:42" }, "geometry": { "type": "LineString", "coordinates": [ [ -73.776878, 40.645065 ], [ -73.992153, 40.662571 ] ] } }
+{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:36:00" }, "geometry": { "type": "LineString", "coordinates": [ [ -73.788028, 40.641508 ], [ -73.97584, 40.670927 ] ] } }
+{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:47:58" }, "geometry": { "type": "LineString", "coordinates": [ [ -73.781855, 40.644749 ], [ -73.980129, 40.663663 ] ] } }
+{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:32:10" }, "geometry": { "type": "LineString", "coordinates": [ [ -73.787494, 40.641559 ], [ -73.974694, 40.673479 ] ] } }
+{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:36:59" }, "geometry": { "type": "LineString", "coordinates": [ [ -73.790138, 40.643342 ], [ -73.982721, 40.662379 ] ] } }
+{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:32:00" }, "geometry": { "type": "LineString", "coordinates": [ [ -73.786952, 40.641248 ], [ -73.97421, 40.676237 ] ] } }
+{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:33:21" }, "geometry": { "type": "LineString", "coordinates": [ [ -73.783892, 40.648514 ], [ -73.979283, 40.669721 ] ] } }
+{ "type": "Feature", "properties": { "start_zone": "JFK Airport", "end_zone": "Park Slope", "trip_time": "00:35:45" }, "geometry": { "type": "LineString", "coordinates": [ [ -73.776643, 40.645272 ], [ -73.978873, 40.66723 ] ] } }
 ```
 </details>
 
@@ -281,9 +283,11 @@ Again, please feel free to open an issue if there is a particular function you w
 | ST_DWithin                  | 🧭        | 🔄        | 🔄            | 🔄         | 🔄 (as POLYGON) |
 | ST_Envelope                 | 🧭        | 🔄        | 🔄            | 🔄         | 🔄 (as POLYGON) |
 | ST_Equals                   | 🧭        | 🔄        | 🔄            | 🔄         | 🔄 (as POLYGON) |
+| ST_FlipCoordinates          | 🦆        | 🦆        | 🦆            | 🦆         | 🦆              |
 | ST_GeomFromText             | 🧭        | 🔄        | 🔄            | 🔄         | 🔄 (as POLYGON) |
 | ST_GeomFromWKB              | 🦆        | 🦆        | 🦆            | 🦆         | 🔄 (as POLYGON) |
 | ST_GeometryType             | 🦆        | 🦆        | 🦆            | 🦆         | 🔄 (as POLYGON) |
+| ST_MakeLine                 | 🦆        |           | 🦆            |            |                 |
 | ST_Intersection             | 🧭        | 🔄        | 🔄            | 🔄         | 🔄 (as POLYGON) |
 | ST_Intersects               | 🧭        | 🔄        | 🔄            | 🔄         | 🔄 (as POLYGON) |
 | ST_IsClosed                 | 🧭        | 🔄        | 🔄            | 🔄         | 🔄 (as POLYGON) |

spatial/include/spatial/core/functions/scalar.hpp

@@ -16,10 +16,12 @@ struct CoreScalarFunctions {
 		RegisterStCollect(context);
 		RegisterStContains(context);
 		RegisterStDistance(context);
+		RegisterStFlipCoordinates(context);
 		RegisterStGeometryType(context);
 		RegisterStGeomFromWKB(context);
 		RegisterStIsEmpty(context);
 		RegisterStLength(context);
+		RegisterStMakeLine(context);
 		RegisterStPoint(context);
 		RegisterStX(context);
 		RegisterStY(context);
@@ -47,6 +49,9 @@ struct CoreScalarFunctions {
 	// ST_Distance
 	static void RegisterStDistance(ClientContext &context);
 
+	// ST_FlipCoordinates
+	static void RegisterStFlipCoordinates(ClientContext &context);
+
 	// ST_GeometryType
 	static void RegisterStGeometryType(ClientContext &context);
 
@@ -59,6 +64,9 @@ struct CoreScalarFunctions {
 	// ST_Length
 	static void RegisterStLength(ClientContext &context);
 
+	// ST_MakeLine
+	static void RegisterStMakeLine(ClientContext &context);
+
 	// ST_Point
 	static void RegisterStPoint(ClientContext &context);
 

spatial/src/spatial/core/functions/scalar/CMakeLists.txt

@@ -7,7 +7,9 @@ set(EXTENSION_SOURCES
     ${CMAKE_CURRENT_SOURCE_DIR}/st_collect.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/st_contains.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/st_distance.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/st_flipcoordinates.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/st_length.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/st_makeline.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/st_geometrytype.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/st_geomfromwkb.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/st_point.cpp

spatial/src/spatial/core/functions/scalar/st_collect.cpp

@@ -12,8 +12,6 @@ namespace spatial {
 
 namespace core {
 
-using namespace spatial::core;
-
 static void CollectFunction(DataChunk &args, ExpressionState &state, Vector &result) {
 	auto &lstate = GeometryFunctionLocalState::ResetAndGet(state);
     auto count = args.size();