CDB_DasymetricDotDensity and fixed for basic DD
This commit is contained in:
Stuart Lynn
@@ -10,45 +10,168 @@
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-- misses per point the funciton accepts before giving up.
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--
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-- Returns: Multipoint with the requested points
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CREATE OR REPLACE FUNCTION cdb_dot_density(geom geometry , no_points Integer, max_iter_per_point Integer DEFAULT 1000)
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RETURNS GEOMETRY AS $$
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DECLARE
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extent GEOMETRY;
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test_point Geometry;
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width NUMERIC;
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height NUMERIC;
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x0 NUMERIC;
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y0 NUMERIC;
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xp NUMERIC;
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yp NUMERIC;
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no_left INTEGER;
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remaining_iterations INTEGER;
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points GEOMETRY[];
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bbox_line GEOMETRY;
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intersection_line GEOMETRY;
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BEGIN
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extent := ST_Envelope(geom);
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width := ST_XMax(extent) - ST_XMIN(extent);
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height := ST_YMax(extent) - ST_YMIN(extent);
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x0 := ST_XMin(extent);
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y0 := ST_YMin(extent);
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no_left := no_points;
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LOOP
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if(no_left=0) THEN
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EXIT;
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END IF;
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yp = y0 + height*random();
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bbox_line = ST_MakeLine(
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ST_SetSRID(ST_MakePoint(yp, x0),4326),
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ST_SetSRID(ST_MakePoint(yp, x0+width),4326)
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);
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intersection_line = ST_Intersection(bbox_line,geom);
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test_point = ST_LineInterpolatePoint(st_makeline(st_linemerge(intersection_line)),random());
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points := points || test_point;
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no_left = no_left - 1 ;
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END LOOP;
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RETURN ST_Collect(points);
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END;
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CREATE OR REPLACE FUNCTION CDB_DotDensity(g geometry, no_points integer, max_iter integer DEFAULT 1000)
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RETURNS SETOF geometry
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AS $$
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DECLARE
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extent GEOMETRY;
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test_point Geometry;
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width NUMERIC;
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height NUMERIC;
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x0 NUMERIC;
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y0 NUMERIC;
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no_left INTEGER;
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sample_points GEOMETRY[];
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points GEOMETRY[];
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BEGIN
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extent := ST_Envelope(g);
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max_iter := 0;
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width := ST_XMax(extent) - ST_XMIN(extent);
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height := ST_YMax(extent) - ST_YMIN(extent);
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x0 := ST_XMin(extent);
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y0 := ST_YMin(extent);
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no_left := no_points;
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LOOP
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IF(no_left<=0 or max_iter=1000) THEN
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RETURN;
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END IF;
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with random_points as(
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SELECT CDB_LATLNG(y0 + height*random(), x0 + width*random()) as p
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FROM generate_series(1,no_left)
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)
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SELECT array_agg(p) from random_points
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WHERE ST_WITHIN(p, g)
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into sample_points;
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RETURN QUERY select * from unnest(sample_points);
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IF sample_points IS NOT null THEN
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no_left = no_left - array_length(sample_points,1);
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END IF;
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max_iter = max_iter + 1;
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END LOOP;
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RETURN;
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END
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$$ LANGUAGE plpgsql;
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--
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-- Creates N points randomly distributed in the specified secondary polygons
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--
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-- @param g - array of the geometries to be turned in to points
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--
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-- @param no_points - the number of points to generate
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--
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-- @params max_iter_per_point - the function generates points in the polygon's bounding box
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-- and discards points which don't lie in the polygon. max_iter_per_point specifies how many
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-- misses per point the funciton accepts before giving up.
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--
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-- Returns: Multipoint with the requested points
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--
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-- Generate a random response based on the weights given
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--
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-- @param array_ids an array of ids representing the category to return
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--
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-- @param weights an array of weights for each category
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--
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-- Returns : The randomly selected ID.
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CREATE OR REPLACE function _cdb_SelectRandomWeights(array_ids numeric[], weights numeric[]) returns NUMERIC
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as $$
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DECLARE
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result NUMERIC;
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BEGIN
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WITH idw as (
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select unnest(array_ids) as id, unnest(weights) as percent
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),
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CTE AS (
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SELECT random() * (SELECT SUM(percent) FROM idw) R
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)
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SELECT *
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FROM (
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SELECT id, SUM(percent) OVER (ORDER BY id) S, R
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FROM idw as percent CROSS JOIN CTE
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) Q
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WHERE S >= R
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ORDER BY id
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LIMIT 1
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into result;
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return result;
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END
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$$ LANGUAGE plpgsql;
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--
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-- Weighted Dot Density
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--
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-- @param no_points the number of points to generate
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--
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-- @param geoms the target geometries to place the points in
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--
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-- @param weights the weight for each of the target polygons
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--
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-- RETURNS set of points
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CREATE OR REPLACE FUNCTION _cdb_WeightedDD(no_points numeric, geoms geometry[], weights numeric[])
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RETURNS SETOF geometry
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AS $$
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DECLARE
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i NUMERIC;
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ids NUMERIC[];
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perGeom NUMERIC[];
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selected_poly NUMERIC;
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BEGIN
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with idseries as (
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select generate_series(1,array_upper(geoms,1)) as id
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)
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select array_agg(id) from idseries into ids;
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FOR i in 1..no_points
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LOOP
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select cdb_crankshaft._cdb_SelectRandomWeights(ids, weights) INTO selected_poly;
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perGeom[selected_poly] = coalesce(perGeom[selected_poly] + 1, 0 );
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END LOOP;
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raise notice 'pergeom %', perGeom;
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FOR i in 1..array_length(ids,1)
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LOOP
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return QUERY
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select cdb_crankshaft.CDB_DotDensity(geoms[i], coalesce(perGeom[i],0)::INTEGER);
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END LOOP;
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END
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$$
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LANGUAGE plpgsql VOLATILE;
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LANGUAGE plpgsql;
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--
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-- Daysymetric Dot Density
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--
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-- @param geom: the geometry that has the
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--
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-- @param no_points: the total number of points to create
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--
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-- @param targetGeoms: the geometry that has the
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--
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-- @param weights: targetGeom weights
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--
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-- RETURNS setof points
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CREATE OR REPLACE FUNCTION CDB_DasymetricDotDensity(geom GEOMETRY, no_points NUMERIC, targetGeoms GEOMETRY[], weights numeric [])
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RETURNS setof GEOMETRY
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AS $$
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BEGIN
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RETURN QUERY
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SELECT cdb_crankshaft._CDB_WeightedDD(no_points, array_agg( ST_INTERSECTION(geom,g)), array_agg(ST_AREA(ST_INTERSECTION(geom,g))*w)::NUMERIC[])
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FROM unnest(targetGeoms) as g , unnest(weights) as w
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WHERE geom && g;
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END
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$$
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LANGUAGE plpgsql;
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