LostGIS

Types

TPV

TPV is Time, Position, Velocity storage type.

create type TPV as (
    -- position
    geom     geometry(point, 3857),
    accuracy float,
    -- velocity
    heading  float,
    speed    float,
    -- time
    ts       timestamptz,
    -- helpers
    source   text,
    osm_id   bigint
);

opening_hours

Implementation for OpenStreetMap opening_hours type. Allows checking whether it's open or closed now, for simple cases.

create type opening_hours as (
    human_readable text,
    is_24          boolean,
    is_valid       boolean,
    week_mask      bit(10080)
);

Functions

overlaps(timestamp, opening_hours)

Check whether timestamp opening_hours are open at timestamp.

  • note timestamp, not timestamptz - you should convert timezone yourself, possibly with a geographical look up;
  • opening_hours need to be casted via text as you cannot create custom input function for type in Postgres;

  • only simple cases (weekdays and hours-minutes) are currently supported.

    select overlaps( '2017-08-13 13:00':: timestamp, 'Mo-Fr 05:00-15:00,19:00-21:00; Sa 05:00-12:00,14:00-21:00; Su 05:00-14:00,17:00-21:00' :: text :: opening_hours )

coslat

Get latitude cosine. Works on projected geometries too.

function coslat(geometry) returns float

coslat (tpv)

Get cosine from latitude.

function coslat(tpv) returns float

Direct calculation of cos(lat) in 3857 without reprojecting it to 4326. Used following expression coslat = cos(asin(tanh(Y / 6378137))).

median

Aggregate function for getting of median

aggregate median( anyelement )

project_position

Get new position for given tpv and new timestamp.

function project_position(TPV, timestamptz) returns TPV

Calculate new position based on speed and heading from given tpv.

ST_AddTime

Add time to array of TPV based on interpolation between start and stop time.

create or replace function ST_AddTime(
    tpvarray             tpv [],
    start_time           timestamptz,
    end_time             timestamptz,
    interpolation_method text default 'length' -- 'length', 'count'
) returns tpv []

ST_AnglesEqual

Comparison of two angles

function ST_AnglesEqual(
    angle1 float,
    angle2 float,
    oneway boolean,
    delta  float default pi() / 4
) returns boolean

ST_AnglesEqualD

Comparison of two angles in degrees.

function ST_AnglesEqualD(
    angle1 float,
    angle2 float,
    oneway boolean,
    delta  float default 45
) returns boolean

ST_Fast_Real_Buffer

It gets buffer in real meters, in contrast to ST_Buffer operating in projection units.

function ST_Fast_Real_Buffer(
    geom geometry, radius float,
    buffer_style_parameters text default ''
) returns geometry

ST_Fast_Real_Length

It gets length in real meters, in contrast to ST_Length operating in projection units.

function ST_Fast_Real_Length(
    geom geometry
) returns double precision

ST_FilterSmallRings

Leaves only large rings in polygon geometry. Useful for map generalization.

function ST_FilterSmallRings(
    geom     geometry,
    min_area float default 0
) returns geometry

ST_GridCell

Get the geometry of rectangular cell of grid.

function ST_GridCell(
    point geometry,
    grid_size float default 500
) returns geometry

Useful for binning point datasets.

ST_LargestSubPolygon

Leave a single polygon from a multipolygon geometry.

function ST_LargestSubPolygon(
    geom geometry
) returns geometry

Useful for map generalization.

ST_LineAngleAtPoint

Given a line and a point at it, find the azimuth of segment the point is closest to.

function ST_LineAngleAtPoint(
    point geometry,
    line  geometry,
    delta float default 1
) returns float

ST_RealOffsetCurve

Return an offset line at a given distance and side from an input line. Radius is in signed value meters.

function ST_RealOffsetCurve(
    geom geometry,
    radius float,
    buffer_style_parameters text default ''
) returns geometry

ST_Safe_Difference

Replacement for ST_Difference, automatically repairing invalid geometries (see also ST_Safe_Repair). 

function ST_Safe_Difference(
    geom_a           geometry,
    geom_b           geometry default null,
    message          text default '[unspecified]',
    grid_granularity double precision default 1
) returns geometry

Also ST_Safe_Difference(geom, null) = geom, which is useful in aggregations.

ST_Safe_Intersection

Replacement for ST_Intersection, automatically repairing invalid geometries (see also ST_Safe_Repair).

function ST_Safe_Intersection(
    geom_a           geometry,
    geom_b           geometry default null,
    message          text default '[unspecified]',
    grid_granularity double precision default 1
) returns geometry

ST_Safe_Repair

Function that tries hard to get a valid geometry out of any geometry.

function ST_Safe_Repair(
    geom    geometry,
    message text default '[unspecified]'
) returns geometry

ST_TimeLineMerge

Sew together an array of segments of track, where (x,y,z) is mapped to (x,y,timestamp).

function ST_TimeLineMerge(
    geoms geometry ( linestringz ) []
) returns setof geometry ( linestringz )