ST_attrIntAverage-AnalyticDB(AnalyticDB)-阿里云帮助中心

Returns the average value of an integer-type attribute field in a trajectory object.

Syntax

int8 ST_attrIntAverage(trajectory traj, cstring attr_field_name);

Parameters

Parameter	Type	Description
`traj`	trajectory	The trajectory object.
`attr_field_name`	cstring	The name of the attribute field.

Examples

The following example calculates the average value of the heading attribute field. The field contains 16 integer values from 0 to 15, so the result is 7.

SELECT ST_attrIntAverage(
  ST_makeTrajectory(
    'STPOINT'::leaftype,
    'LINESTRING(-179.48077 51.72814,-179.46731 51.74634,-179.46502 51.74934,-179.46183 51.75378,-179.45943 51.75736,-179.45560 51.76273,-179.44845 51.77186,-179.43419 51.78977,-179.41259 51.81643,-179.41001 51.81941,-179.40751 51.82223,-179.40497 51.82505,-179.40242 51.82796,-179.39981 51.83095,-179.39734 51.83398,-179.39499 51.83709)'::geometry,
    ARRAY[
      '2017-01-15 09:06:39'::timestamp,
      '2017-01-15 09:14:48',
      '2017-01-15 09:13:39',
      '2017-01-15 09:16:28',
      '2017-01-15 09:19:48',
      '2017-01-15 09:17:48',
      '2017-01-15 09:23:19',
      '2017-01-15 09:34:40',
      '2017-01-15 09:30:28',
      '2017-01-15 09:36:59',
      '2017-01-15 09:38:09',
      '2017-01-15 09:39:18',
      '2017-01-15 09:40:40',
      '2017-01-15 09:47:38',
      '2017-01-15 21:18:30',
      '2017-01-15 09:48:49'
    ],
    '{"leafcount": 16, "attributes": {"heading": {"type": "integer", "length": 4, "nullable": false, "value": [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]}}}'
  ),
  'heading'
);

Output:

 st_attrintaverage
-------------------
                 7