PolyBuild
Build spatial shapes from coordinate data by grouping and ordering points into either polygons (closed shapes) or polylines (open lines). Use this gem to convert raw latitude/longitude values into structured spatial geometries for mapping, analysis, or downstream geospatial operations.
- Polygon: Uses the
POLYGON()format to create a closed shape. - Polyline: Uses the
LINESTRING()format to create an open path.
Input and Output
The PolyBuild gem accepts the following input and output.
| Port | Description |
|---|---|
| in0 | Input dataset containing pairs of columns with latitude and longitude coordinates, along with fields for grouping and ordering coordinates. |
| out | Output dataset with one row per group, each containing a generated polygon or polyline in WKT format. |
Parameters
Configure the PolyBuild gem using the following parameters.
| Parameter | Description |
|---|---|
| Build Method | Select the type of spatial geometry to create from your coordinate data: • Select Sequence Polygon for closed areas, such as boundaries or zones • Select Sequence Polyline for open paths, such as routes or trails |
| Longitude Column Name | Column containing longitude values. Must be in decimal degrees (e.g., -122.4194). |
| Latitude Column Name | Column containing latitude values. Must be in decimal degrees (e.g., 37.7749). |
| Group Field | Column used to divide coordinates into distinct shapes. Example: Use the state_name column to identify polygons for each state border.Only one column is supported for grouping. |
| Sequence Field | Column that defines the drawing order of points within each group. This column can be any sortable type (e.g., integers, timestamps, strings). The points will be connected in ascending order. |
Example
Assume you have the following routes table for public transportation routes.
| route_id | stop_schedule | latitude | longitude |
|---|---|---|---|
| bus_21_morning | 2025-07-16T08:00:00Z | 37.7749 | -122.4194 |
| bus_21_morning | 2025-07-16T08:10:00Z | 37.7793 | -122.4192 |
| bus_21_morning | 2025-07-16T08:20:00Z | 37.7796 | -122.4148 |
| tram_5_evening | 2025-07-16T18:00:00Z | 34.0522 | -118.2437 |
| tram_5_evening | 2025-07-16T18:10:00Z | 34.0565 | -118.2470 |
| tram_5_evening | 2025-07-16T18:20:00Z | 34.0580 | -118.2417 |
To transform each route into a polyline geometry:
- Add the PolyBuild gem to your pipeline canvas.
- Connect the
routestable to the PolyBuild input port. - Open the PolyBuild gem configuration.
- For Build Method, select Sequence Polyline.
- For Longitude Column Name, select the
longitudecolumn. - For Latitude Column Name, select the
latitudecolumn. - For Group Field, select the
route_idcolumn. - For Sequence Field, select the
stop_schedulecolumn. - Save and run the gem.
Result
The PolyBuild gem outputs a table including a polyline for each route.
| route_id | wkt |
|---|---|
| bus_21_morning | LINESTRING (-122.4194 37.7749, -122.4192 37.7793, -122.4148 37.7796) |
| tram_5_evening | LINESTRING (-118.2437 34.0522, -118.2470 34.0565, -118.2417 34.0580) |