syntax

.travis.yml

@@ -36,7 +36,10 @@ before_install:
   - sudo apt-get -y remove --purge postgresql-9.3
   - sudo apt-get -y remove --purge postgresql-9.4
   - sudo apt-get -y remove --purge postgresql-9.5
-  - sudo apt-get -y remove --purge postgis
+  - sudo rm -rf /var/lib/postgresql/
+  - sudo rm -rf /var/log/postgresql/
+  - sudo rm -rf /etc/postgresql/
+  - sudo apt-get -y remove --purge postgis-2.2
   - sudo apt-get -y autoremove
 
   - sudo apt-get -y install postgresql-9.5=9.5.2-3cdb2

src/pg/sql/30_dot_density.sql

@@ -10,24 +10,26 @@
 -- misses per point the funciton accepts before giving up.
 --
 -- Returns: Multipoint with the requested points
-CREATE OR REPLACE FUNCTION cdb_dot_density(geom geometry , no_points Integer, max_iter_per_point Integer DEFAULT 1000)
-RETURNS GEOMETRY AS $$
+
+CREATE OR REPLACE FUNCTION CDB_DotDensity(g geometry(Polygon, 4326), no_points integer, max_iter integer DEFAULT 1000)
+ RETURNS SETOF geometry(Point, 4326)
+AS $$
  DECLARE
      extent GEOMETRY;
+     eq_area_geom GEOMETRY;
      test_point Geometry;
+     iter     NUMERIC;
      width    NUMERIC;
      height   NUMERIC;
      x0       NUMERIC;
      y0       NUMERIC;
-  xp                   NUMERIC;
-  yp                   NUMERIC;
      no_left  INTEGER;
-  remaining_iterations INTEGER;
+     sample_points GEOMETRY[];
      points   GEOMETRY[];
-  bbox_line            GEOMETRY;
-  intersection_line    GEOMETRY;
  BEGIN
-  extent  := ST_Envelope(geom);
+   eq_area_geom := ST_TRANSFORM(g, 2163);
+   extent   := ST_Envelope(eq_area_geom);
+   iter := 0;
    width    := ST_XMax(extent) - ST_XMIN(extent);
    height   := ST_YMax(extent) - ST_YMIN(extent);
    x0       := ST_XMin(extent);
@@ -35,20 +37,165 @@ BEGIN
    no_left  := no_points;
 
    LOOP
-    if(no_left=0) THEN
-      EXIT;
+     IF(no_left <= 0 or iter >= max_iter) THEN
+       RETURN;
      END IF;
-    yp = y0 + height*random();
-    bbox_line  = ST_MakeLine(
-      ST_SetSRID(ST_MakePoint(yp, x0),4326),
-      ST_SetSRID(ST_MakePoint(yp, x0+width),4326)
-    );
-    intersection_line = ST_Intersection(bbox_line,geom);
-  	test_point = ST_LineInterpolatePoint(st_makeline(st_linemerge(intersection_line)),random());
-	  points := points || test_point;
-	  no_left = no_left - 1 ;
+
+
+    with random_points as(
+        SELECT ST_SetSRID(ST_MAKEPOINT( x0 + width*random(), y0 + height*random()), 2163) as p
+        FROM generate_series(1,no_left)
+     )
+     SELECT array_agg(p) from random_points
+     WHERE ST_WITHIN(p, eq_area_geom)
+     into sample_points;
+
+     RETURN QUERY select ST_TRANSFORM(a, 4326) from unnest(sample_points) as a;
+
+     IF sample_points IS NOT null THEN
+        no_left := no_left - array_length(sample_points, 1);
+     END IF;
+     iter = iter + 1;
    END LOOP;
-  RETURN ST_Collect(points);
+
+   RETURN;
  END;
+$$ LANGUAGE plpgsql;
+
+-- DEPRECATED
+
+CREATE OR REPLACE FUNCTION cdb_dot_density(geom geometry, no_points Integer, max_iter_per_point Integer DEFAULT 1000)
+  RETURNS GEOMETRY
+AS $$
+DECLARE
+final_points GEOMETRY;
+
+BEGIN
+
+  with new_points as(
+    SELECT * FROM CDB_DotDensity(geom, no_points, max_iter_per_point) as a
+  )
+  SELECT ST_Collect(a) FROM new_points
+  into final_points;
+  RETURN final_points;
+
+END;
+$$ LANGUAGE plpgsql;
+
+--
+-- Creates N points randomly distributed in the specified secondary polygons
+--
+-- @param g - array of the geometries to be turned in to points
+--
+-- @param no_points - the number of points to generate
+--
+-- @params max_iter_per_point - the function generates points in the polygon's bounding box
+-- and discards points which don't lie in the polygon. max_iter_per_point specifies how many
+-- misses per point the funciton accepts before giving up.
+--
+-- Returns: Multipoint with the requested points
+
+
+
+--
+-- Generate a random response based on the weights given
+--
+-- @param array_ids an array of ids representing the category to return
+--
+-- @param weights an array of weights for each category
+--
+-- Returns : The randomly selected ID.
+
+CREATE OR REPLACE function _cdb_SelectRandomWeights(array_ids numeric[], weights numeric[]) returns NUMERIC
+ as $$
+ DECLARE
+     result NUMERIC;
+ BEGIN
+
+     WITH idw as (
+         select unnest(array_ids) as id, unnest(weights) as percent
+     ),
+     CTE AS (
+         SELECT random() * (SELECT SUM(percent) FROM idw) R
+     )
+     SELECT *
+     FROM (
+         SELECT id, SUM(percent) OVER (ORDER BY id) S, R
+         FROM idw as percent CROSS JOIN CTE
+     ) Q
+     WHERE S >= R
+     ORDER BY id
+     LIMIT 1
+     into result;
+     return result;
+ END
+ $$ LANGUAGE plpgsql;
+
+--
+-- Weighted Dot Density
+--
+-- @param no_points the number of points to generate
+--
+-- @param geoms the target geometries to place the points in
+--
+-- @param weights the weight for each of the target polygons
+--
+-- RETURNS set of points
+
+CREATE OR REPLACE FUNCTION _cdb_WeightedDD(no_points numeric, geoms geometry[], weights numeric[])
+ RETURNS SETOF geometry
+AS $$
+DECLARE
+ i NUMERIC;
+ ids NUMERIC[];
+ perGeom NUMERIC[];
+ selected_poly NUMERIC;
+BEGIN
+ with idseries as (
+     select generate_series(1,array_upper(geoms,1)) as id
+ )
+ select array_agg(id) from idseries into ids;
+
+ FOR i in 1..no_points
+ LOOP
+    select cdb_crankshaft._cdb_SelectRandomWeights(ids, weights) INTO selected_poly;
+    perGeom[selected_poly] = coalesce(perGeom[selected_poly] + 1, 0 );
+ END LOOP;
+
+ raise notice 'pergeom %', perGeom;
+
+ FOR i in 1..array_length(ids,1)
+ LOOP
+     return QUERY
+     select cdb_crankshaft.CDB_DotDensity(geoms[i], coalesce(perGeom[i],0)::INTEGER);
+ END LOOP;
+END
 $$
-LANGUAGE plpgsql VOLATILE;
+LANGUAGE plpgsql;
+
+
+--
+-- Daysymetric Dot Density
+--
+-- @param geom: the geometry that has the
+--
+-- @param no_points: the total number of points to create
+--
+-- @param targetGeoms: the geometry that has the
+--
+-- @param weights: targetGeom weights
+--
+-- RETURNS setof points
+
+CREATE OR REPLACE FUNCTION CDB_DasymetricDotDensity(geom GEOMETRY, no_points NUMERIC, targetGeoms GEOMETRY[], weights numeric [])
+RETURNS setof GEOMETRY
+AS $$
+  BEGIN
+    RAISE NOTICE 'running Dasymetric';
+    RETURN QUERY
+        SELECT cdb_crankshaft._CDB_WeightedDD(no_points, array_agg( ST_INTERSECTION(geom,g)), array_agg(ST_AREA(ST_INTERSECTION(geom,g))*w)::NUMERIC[])
+        FROM unnest(targetGeoms) as g , unnest(weights) as w
+        WHERE geom && g;
+  END
+$$
+LANGUAGE plpgsql;

src/pg/test/expected/04_dot_density_test.out

@@ -1,16 +0,0 @@
-WITH g AS (
-  SELECT ST_Buffer(ST_SetSRID(ST_MakePoint(0,0),4326)::geometry, 1000)::geometry AS g
-),
-points AS(
-  SELECT (
-    ST_Dump(
-      cdb_crankshaft.cdb_dot_density(g.g, 100)
-    )
-  ).geom AS p FROM g
-)
-SELECT count(*), sum(CASE WHEN ST_Contains(g,p) THEN 1 ELSE 0 END) FROM points, g
- count | sum 
--------+-----
-   100 | 100
-(1 row)
-

src/pg/test/sql/04_dot_density_test.sql

@@ -1,12 +0,0 @@
-WITH g AS (
-  SELECT ST_Buffer(ST_SetSRID(ST_MakePoint(0,0),4326)::geometry, 1000)::geometry AS g
-),
-points AS(
-  SELECT (
-    ST_Dump(
-      cdb_crankshaft.cdb_dot_density(g.g, 100)
-    )
-  ).geom AS p FROM g
-)
-
-SELECT count(*), sum(CASE WHEN ST_Contains(g,p) THEN 1 ELSE 0 END) FROM points, g