dlt Operator

The dlt (distance less than) operator in the Time series API allows users to filter results based on proximity to a specific point, within a defined radius. This feature makes it easy to search within a circular area around a location, offering a simpler alternative to bounding box filters (bbc, bbi).

Operator Syntax

• Operator: dlt
• Purpose: Filters items within a certain distance from a point.
• Parameters:
  • distance (required): The radius in meters within which to search.
  • x (required): Longitude of the central point.
  • y (required): Latitude of the central point.
  • SRID (optional): Spatial Reference System Identifier (defaults to 4326).

Example Usage

• Basic Usage: coordinate.dlt.(distance, x, y, SRID)

To retrieve parking stations within a 3 km radius of Meran’s center:

https://mobility.api.opendatahub.com/v2/flat,node/ParkingStation?where=scoordinate.dlt.(3000,11.158682,46.668853)

To retrieve all stations within 5 km from coordinates (11.2, 46.7):

https://mobility.api.opendatahub.com/v2/flat,node/ParkingStation?where=scoordinate.dlt.(5000,11.2,46.7)

Common Pitfalls

• Coordinate Order: Ensure coordinates are in longitude, latitude order. Note that Google Maps typically uses latitude, longitude, so be cautious when copying coordinates.
• SRID: If omitted, the SRID defaults to 4326. Use a specific SRID if required by your application.

Related Operators

• bbc (Bounding Box Contain): Returns items completely within a specified bounding box.
• bbi (Bounding Box Intersect): Returns items partially within a bounding box.