获得轨迹属性字段类型为float的属性平均值。
语法
float8 ST_attrFloatAverage(trajectory traj, cstring attr_field_name);参数
| 参数名称 | 描述 |
|---|---|
| traj | 需要获得属性信息的轨迹。 |
| attr_field_name | 指定的属性字段名称。 |
示例
select st_attrFloatAverage(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 09:13:39','2017-01-15 09:14:48','2017-01-15 09:16:28','2017-01-15 09:17:48','2017-01-15 09:19:48','2017-01-15 09:23:19','2017-01-15 09:30:28','2017-01-15 09:34:40','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 09:48:49','2017-01-15 21:18:30'], '{"leafcount": 16, "attributes" : {"heading" : {"type": "float", "length": 4, "nullable" : false,"value": [23.0,23.0,23.0,23.0,21.0,21.0,72.0,72.0,72.0,72.0,73.0,74.0,73.0,73.0,73.0,73.0]}}}' ),'heading');
st_attrfloataverage
---------------------
53.8125
(1 row)