locationApproximate (Stream Function)
Calculates the average location of locationRecorder using the collection iBeacons in which the location recorder resides.
Syntax
geo:locationApproximate(<STRING> location.recorder, <DOUBLE> latitude, <DOUBLE> longitude, <STRING> sensor.proximity, <STRING> sensor.uuid, <DOUBLE> sensor.weight, <LONG> timestamp)
Query Parameters
| Name | Description | Possible Data Types | Optional | Dynamic |
|---|---|---|---|---|
| location.recorder | Unique ID of the specified object or item. | STRING | No | No |
| latitude | Latitude of the iBeacon. | DOUBLE | No | No |
| longitude | Longitude of the iBeacon. | DOUBLE | No | No |
| sensor.proximity | Proximity given by the iBeacon (eg: ENTER, RANGE, EXIT). | STRING | No | No |
| sensor.uuid | Unique ID of the iBeacon. | STRING | No | No |
| sensor.weight | Approximation weight of the iBeacon (e.g. approximate distance from the iBeacon). | DOUBLE | No | No |
| timestamp | Timestamp of the log you want to use to remove iBeacon from a collection after no new log for 5 minutes. | LONG | No | No |
Example 1
geo:locationApproximate("person1", 6.876657, 79.897648, "ENTER", "uuid1", 20.0d, 1452583935L)
The geo:locationApproximate() function calculates an approximate location given the parameters. Here, the function takes "person1" as the identifier, 6.876657 and 79.897648 as the latitude and longitude respectively, "ENTER" as the action, "uuid1" as the UUID, 20.0d as the accuracy, and 1452583935L as the timestamp. The function outputs an approximation of the location, returning 6.876657000000001 for latitude and 79.89764800000001 for longitude.
Example 2
CREATE STREAM InputStream (id string, latitude double, longitude double, action string, uuid string, accuracy double, timestamp long);
CREATE SINK STREAM OutputStream (id string, averagedLatitude double, averagedLongitude double, averageExist bool);
@info(name = 'approximateLocation')
INSERT INTO OutputStream
SELECT id, averagedLatitude, averagedLongitude, averageExist
FROM InputStream#geo:locationApproximate(id, latitude, longitude, action, uuid, accuracy, timestamp);
In this streaming data example, two streams are created: InputStream for input data and OutputStream for the output.
The InputStream includes fields for id (representing the unique ID of the specific object or item being tracked), latitude and longitude (representing the coordinates of the iBeacon device), action (representing the proximity provided by the iBeacon), uuid (representing the unique ID of the iBeacon), accuracy (representing the approximation weight of the iBeacon), and timestamp (representing the timestamp of the log).
The OutputStream is set to receive the id, averagedLatitude, averagedLongitude, and a boolean field averageExist that will be true if the calculation was successful, and false otherwise.
The query named approximateLocation listens for events from the InputStream and applies the function geo:locationApproximate(id, latitude, longitude, action, uuid, accuracy, timestamp) to each event. This function calculates the average location of the location.recorder using the collection of iBeacons where the location recorder resides.
The output from this function - the id, averagedLatitude, averagedLongitude, and averageExist - is then inserted into the OutputStream. In essence, this query is continually calculating an average position based on the inputs from the InputStream and updating OutputStream with the calculated averages.