dataservices-api/doc/routing_functions.md

Routing functions

The following rouging functions are available, grouped by categories.

Isolines

This function provides an isolines generator sirves based on time or distance.

cdb_isodistance(source geometry, mode text, range integer[], options text[])

Arguments

Name	Type	Description	Accepted values
source	geometry	Source point, in 4326 projection, taken as the start point
mode	geometry	Type of transport used to calculate the isolines.	car and walk
range	integer[]	Range of the isoline in meters
options	text[]	Multiple options to add more capabilities to the analysis. See the options section to know more.

Options

The options values must be pass in the following way: option=value.

Name	Type	Description	Accepted values
is_destination	boolean	If is true the source point is the destination instead of the starting one.
mode_type	text	Type of route calculation	shortest or fastest. By default is shortest
mode_traffic	text	Use the traffic data to calculate the route.	enabled or disabled. By default is disabled
singlecomponent	boolean	If set to true the isoline service will always return single polygon, instead of creating a separate polygon for each ferry separated island.	true or false. Default value is false.
resolution	text	Allows to specify level of detail needed for the isoline polygon. Unit is meters per pixel. Higher resolution may cause increased response time from the service.
maxpoints	text	Allows to limit amount of points in the returned isoline. If isoline consists of multiple components, sum of points from all components is considered. Each component will have at least 2 points, so it is possible that more points than maxpoints value will be returned. This is in case when 2 * number of components is higher than maxpoints. Enlarging number of maxpoints may cause increased response time from the service.
quality	text	Allows to reduce the quality of the isoline in favor of the response time.	1, 2, 3. Default value is 1 and it is the best quality.

Returns

Name	Type	Description
center	geometry	Source point, in 4326 projection, taken as the start point
data_range	integer	The range that belongs to the generated isoline.
the_geom	geometry (multipolygon)	Geometry of the generated isoline in 4326 projection.

Example

Select

SELECT * FROM cdb_isodistance('POINT(-3.70568 40.42028)'::geometry, 'car', ARRAY[1000,2000]::integer[]);
SELECT * FROM cdb_isodistance('POINT(-3.70568 40.42028)'::geometry, 'walk', ARRAY[1000]::integer[], ARRAY['mode_traffic=enabled','quality=3']::text[]);

cdb_isochrone(source geometry, mode text, range integer[], options text[])

This function uses the same parameters and info as the cdb_isodistance function with the difference that the range is measured in seconds instead of meters

Example

Select

SELECT * FROM cdb_isochrone('POINT(-3.70568 40.42028)'::geometry, 'car', ARRAY[300,900,12000]::integer[]);
SELECT * FROM cdb_isochrone('POINT(-3.70568 40.42028)'::geometry, 'walk', ARRAY[300,900]::integer[], ARRAY['mode_traffic=enabled','quality=3']::text[]);