This function constructs a trajectory object.

Syntax

trajectory  ST_makeTrajectory (leaftype type, geometry spatial, tsrange timespan, cstring attrs_json);
trajectory  ST_makeTrajectory (leaftype type, geometry spatial, timestamp start, timestamp end, cstring attrs_json);
trajectory  ST_makeTrajectory (leaftype type, geometry spatial, timestamp[] timeline, cstringattrs_json);
trajectory ST_makeTrajectory (leaftype type, float8[] x, float8[] y, integer srid, timestamp[] timeline, text[] attr_field_names, int4[] attr_int4, float8[] attr_float8, text[] attr_cstring, anyarrayattr_any);

Parameters

Parameter Description
type The trajectory type. Only ST_POINT is supported.
spatial The spatial geometry object based on a linestring or point object.
timespan The time range of the trajectory, which contains the start time and end time.
start The start time of the trajectory.
end The end time of the trajectory.
timeline The trajectory timeline. The number of time points must be the same as that of points in the linestring object.
attrs_json The trajectory attributes and events, in JSON format. The value can be null.
attr_field_names The array of the names of all attribute fields for the trajectory.
x The x-axis (array) for the geometry object.
y The y-axis (array) for the geometry object.
srid The spatial reference system identifier (SRID) of the trajectory. This parameter is required.
  1. The format of the attrs_json parameter is as follows:
    {
      "leafcount": 3,
      "attributes": {
        "velocity": {
          "type": "integer",
          "length": 2,
          "nullable": true,
          "value": [
            120,
            null,
            140
          ]
        },
        "accuracy": {
          "type": "float",
          "length": 4,
          "nullable": false,
          "value": [
            120,
            130,
            140
          ]
        },
        "bearing": {
          "type": "float",
          "length": 8,
          "nullable": false,
          "value": [
            120,
            130,
            140
          ]
        },
        "vesname": {
          "type": "string",
          "length": 20,
          "nullable": true,
          "value": [
            "dsff",
            "fgsd",
            null
          ]
        },
        "active": {
          "type": "timestamp",
          "nullable": false,
          "value": [
            "Fri Jan 01 14:30:00 2010",
            "Fri Jan 01 15:00:00 2010",
            "Fri Jan 01 15:30:00 2010"
          ]
        }
      },
      "events": [
        {
          "1": "Fri Jan 01 14:30:00 2010"
        },
        {
          "2": "Fri Jan 01 15:00:00 2010"
        },
        {
          "3": "Fri Jan 01 15:30:00 2010"
        }
      ]
    }

    leafcount specifies the number of trajectory points in the trajectory object. Its value must be consistent with the number of spatial points in the spatial geometry object. Its value is also the same as the number of values for each attribute field. All attribute fields must have the same number of values.

    attributes specifies trajectory attributes, including the definitions and a sequence of values for all attribute fields. It must co-exist with leafcount. Attribute definitions and requirements are as follows:
    • An attribute name can contain a maximum of 60 characters.
    • type: the field type. Valid values: integer, float, string, timestamp, and bool.
    • length: the field length. The value varies with the field type. integer: 1, 2, 4, or 8. float: 4 or 8. string: customizable. (If not specified, the default length is 64 and the maximum length is 253. The length value is the actual number of characters and excludes the end identifier.) timestamp: If not specified, the default length is 8. bool: If not specified, the default length is 1.
    • nullable: indicates whether the field can be null. Valid values: true and false. Default value: true.
    • value: the sequence of field values, listed in JSON array format. If a value is null, null is displayed.

    events specifies trajectory events. Multiple events are listed in JSON array format. Each array element is expressed in key:value format, where key indicates the event type and value indicates the event time.

  2. If only the timespan parameter or the start and end parameters are specified as time, such as in syntax 1 and syntax 2, this constructor can interpolate time points based on the number of spatial points to generate the trajectory timeline.
  3. If all the four types of syntax do not meet your requirements, you can customize the parameters following the first six fixed parameters to create a custom ST_makeTrajectory constructor as follows:
    CREATE OR REPLACE FUNCTION  _ST_MakeTrajectory(type leaftype, x float8[], y float8[] , srid integer, timespan timestamp[],
        attrs_name cstring[], attr1 float8[], attr2 float4[], attr3 timestamp[])
        RETURNS trajectory
        AS '$libdir/libpg-trajectoryxx','sqltr_traj_make_all_array'
        LANGUAGE 'c' IMMUTABLE Parallel SAFE;

Examples

-- (1) ST_MakeTrajectory with a time range
select ST_MakeTrajectory('STPOINT'::leaftype, st_geomfromtext('LINESTRING (114 35, 115 36, 116 37)', 4326), '[2010-01-01 14:30, 2010-01-01 15:30)'::tsrange, '{"leafcount":3,"attributes":{"velocity": {"type": "integer", "length": 2,"nullable" : true,"value": [120, 130, 140]}, "accuracy": {"type": "float", "length": 4, "nullable" : false,"value": [120, 130, 140]}, "bearing": {"type": "float", "length": 8, "nullable" : false,"value": [120, 130, 140]}, "vesname": {"type": "string", "length": 20, "nullable" : true,"value": ["adsf", "sdf", "sdfff"]}, "active": {"type": "timestamp", "nullable" : false,"value": ["Fri Jan 01 14:30:00 2010", "Fri Jan 01 15:00:00 2010", "Fri Jan 01 15:30:00 2010"]}}, "events": [{"1" : "Fri Jan 01 14:30:00 2010"}, {"2" : "Fri Jan 01 15:00:00 2010"}, {"3" : "Fri Jan 01 15:30:00 2010"}]}');                        st_maketrajectory         
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 {"trajectory":{"version":1,"type":"STPOINT","leafcount":3,"start_time":"2010-01-01 14:30:00","end_time":"2010-01-01 15:30:00","spatial":"SRID=4326;LINESTRING(114 35,115 36,116 37)","timeline":["2010-01-01 14:30:00","2010-01-01 15:00:00","2010-01-01 15:30:00"],"attributes":{"leafcount":3,"velocity":{"type":"integer","length":2,"nullable":true,"value":[120,130,140]},"accuracy":{"type":"float","length":4,"nullable":false,"value":[120.0,130.0,140.0]},"bearing":{"type":"float","length":8,"nullable":false,"value":[120.0,130.0,140.0]},"vesname":{"type":"string","length":20,"nullable":true,"value":["adsf","sdf","sdfff"]},"active":{"type":"timestamp","length":8,"nullable":false,"value":["2010-01-01 14:30:00","2010-01-01 15:00:00","2010-01-01 15:30:00"]}},"events":[{"1":"2010-01-01 14:30:00"},{"2":"2010-01-01 15:00:00"},{"3":"2010-01-01 15:30:00"}]}}
(1 row)

-- (2) ST_MakeTrajectory with a start timestamp and an end timestamp
select ST_MakeTrajectory('STPOINT'::leaftype, st_geomfromtext('LINESTRING (114 35, 115 36, 116 37)', 4326), '2010-01-01 14:30'::timestamp, '2010-01-01 15:30'::timestamp, '{"leafcount":3,"attributes":{"velocity": {"type": "integer", "length": 2,"nullable" : true,"value": [120, 130, 140]}, "accuracy": {"type": "float", "length": 4, "nullable" : false,"value": [120, 130, 140]}, "bearing": {"type": "float", "length": 8, "nullable" : false,"value": [120, 130, 140]}, "vesname": {"type": "string", "length": 20, "nullable" : true,"value": ["adsf", "sdf", "sdfff"]}, "active": {"type": "timestamp", "nullable" : false,"value": ["Fri Jan 01 14:30:00 2010", "Fri Jan 01 15:00:00 2010", "Fri Jan 01 15:30:00 2010"]}}, "events": [{"1" : "Fri Jan 01 14:30:00 2010"}, {"2" : "Fri Jan 01 15:00:00 2010"}, {"3" : "Fri Jan 01 15:30:00 2010"}]}');                        st_maketrajectory         
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 {"trajectory":{"version":1,"type":"STPOINT","leafcount":3,"start_time":"2010-01-01 14:30:00","end_time":"2010-01-01 15:30:00","spatial":"SRID=4326;LINESTRING(114 35,115 36,116 37)","timeline":["2010-01-01 14:30:00","2010-01-01 15:00:00","2010-01-01 15:30:00"],"attributes":{"leafcount":3,"velocity":{"type":"integer","length":2,"nullable":true,"value":[120,130,140]},"accuracy":{"type":"float","length":4,"nullable":false,"value":[120.0,130.0,140.0]},"bearing":{"type":"float","length":8,"nullable":false,"value":[120.0,130.0,140.0]},"vesname":{"type":"string","length":20,"nullable":true,"value":["adsf","sdf","sdfff"]},"active":{"type":"timestamp","length":8,"nullable":false,"value":["2010-01-01 14:30:00","2010-01-01 15:00:00","2010-01-01 15:30:00"]}},"events":[{"1":"2010-01-01 14:30:00"},{"2":"2010-01-01 15:00:00"},{"3":"2010-01-01 15:30:00"}]}}
(1 row)

-- (3) ST_MakeTrajectory with a timestamp array
select ST_MakeTrajectory('STPOINT'::leaftype, st_geomfromtext('LINESTRING (114 35, 115 36, 116 37)', 4326), ARRAY['2010-01-01 14:30'::timestamp, '2010-01-01 15:00'::timestamp, '2010-01-01 15:30'::timestamp], '{"leafcount":3,"attributes":{"velocity": {"type": "integer", "length": 2,"nullable" : true,"value": [120, 130, 140]}, "accuracy": {"type": "float", "length": 4, "nullable" : false,"value": [120, 130, 140]}, "bearing": {"type": "float", "length": 8, "nullable" : false,"value": [120, 130, 140]}, "vesname": {"type": "string", "length": 20, "nullable" : true,"value": ["adsf", "sdf", "sdfff"]}, "active": {"type": "timestamp", "nullable" : false,"value": ["Fri Jan 01 14:30:00 2010", "Fri Jan 01 15:00:00 2010", "Fri Jan 01 15:30:00 2010"]}}, "events": [{"1" : "Fri Jan 01 14:30:00 2010"}, {"2" : "Fri Jan 01 15:00:00 2010"}, {"3" : "Fri Jan 01 15:30:00 2010"}]}');                        st_maketrajectory         
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 {"trajectory":{"version":1,"type":"STPOINT","leafcount":3,"start_time":"2010-01-01 14:30:00","end_time":"2010-01-01 15:30:00","spatial":"SRID=4326;LINESTRING(114 35,115 36,116 37)","timeline":["2010-01-01 14:30:00","2010-01-01 15:00:00","2010-01-01 15:30:00"],"attributes":{"leafcount":3,"velocity":{"type":"integer","length":2,"nullable":true,"value":[120,130,140]},"accuracy":{"type":"float","length":4,"nullable":false,"value":[120.0,130.0,140.0]},"bearing":{"type":"float","length":8,"nullable":false,"value":[120.0,130.0,140.0]},"vesname":{"type":"string","length":20,"nullable":true,"value":["adsf","sdf","sdfff"]},"active":{"type":"timestamp","length":8,"nullable":false,"value":["2010-01-01 14:30:00","2010-01-01 15:00:00","2010-01-01 15:30:00"]}},"events":[{"1":"2010-01-01 14:30:00"},{"2":"2010-01-01 15:00:00"},{"3":"2010-01-01 15:30:00"}]}}
(1 row)  

-- (4) ST_MakeTrajectory with null attrs_json
select ST_MakeTrajectory('STPOINT'::leaftype, st_geomfromtext('LINESTRING (114 35, 115 36, 116 37)', 4326), '[2010-01-01 14:30, 2010-01-01 15:30)'::tsrange, null); 
                        st_maketrajectory                                                                                                                  
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{"trajectory":{"leafsize":3,"starttime":"Fri Jan 01 14:30:00 2010","endtime":"Fri Jan 01 15:30:00 2010","spatial":"LINESTRING(114 35,115 36,116 37)","timeline":["Fri Jan 01 14:30:00 2010","Fri Jan 01 15:00:00 2010","Fri Jan 01 15:30:00 2010"]}}
(1 row)

-- (5) ST_MakeTrajectory that constructs a trajectory object from points
select st_makeTrajectory('STPOINT'::leaftype, ARRAY[1::float8], ARRAY[2::float8], 4326, ARRAY['2010-01-01 11:30'::timestamp], ARRAY['velocity'], ARRAY[1::int4], NULL, NULL, NULL::anyarray);
                                                            st_maketrajectory                             

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
{"trajectory":{"version":1,"type":"STPOINT","leafcount":1,"start_time":"2010-01-01 11:30:00","end_time":"2010-01-01 11:30:00","spatial":"SRID=4326;POINT(1 2)","timeline":["2010-01-01 11:30:00"],"attributes":{"leafcount":1,"velocity":{"type":"integer","length":4,"nullable":true,"value":[1]}}}}
(1 row)