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dot density fixes for geom's with holes and equal area

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This commit is contained in:
Stuart Lynn
2016-11-30 22:34:46 +00:00
parent b8fe05b388
commit 1f3b74e54f
3 changed files with 9 additions and 34 deletions
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15
src/pg/sql/30_dot_density.sql
View File

@@ -16,6 +16,7 @@ CREATE OR REPLACE FUNCTION CDB_DotDensity(g geometry, no_points integer, max_ite
AS $$
DECLARE
extent GEOMETRY;
eq_area_geom GEOMETRY;
test_point Geometry;
width NUMERIC;
height NUMERIC;
@@ -25,8 +26,8 @@ AS $$
sample_points GEOMETRY[];
points GEOMETRY[];
BEGIN
extent := ST_Envelope(g);
eq_area_geom := ST_TRANSFORM(g,2163);
extent := ST_Envelope(eq_area_geom);
max_iter := 0;
width := ST_XMax(extent) - ST_XMIN(extent);
height := ST_YMax(extent) - ST_YMIN(extent);
@@ -38,16 +39,17 @@ AS $$
IF(no_left<=0 or max_iter=1000) THEN
RETURN;
END IF;
with random_points as(
SELECT CDB_LATLNG(y0 + height*random(), x0 + width*random()) as p
with random_points as(
SELECT ST_SetSRID(ST_MAKEPOINT( x0 + width*random(),y0 + height*random()), 2163) as p
FROM generate_series(1,no_left)
)
SELECT array_agg(p) from random_points
WHERE ST_WITHIN(p, g)
WHERE ST_WITHIN(p, eq_area_geom)
into sample_points;
RETURN QUERY select * from unnest(sample_points);
RETURN QUERY select ST_TRANSFORM(a,4236) from unnest(sample_points) as a;
IF sample_points IS NOT null THEN
no_left = no_left - array_length(sample_points,1);
@@ -168,6 +170,7 @@ CREATE OR REPLACE FUNCTION CDB_DasymetricDotDensity(geom GEOMETRY, no_points NUM
RETURNS setof GEOMETRY
AS $$
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

16
src/pg/test/expected/04_dot_density_test.out
View File

@@ -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)

12
src/pg/test/sql/04_dot_density_test.sql
View File

@@ -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