137 lines
4.7 KiB
PL/PgSQL
137 lines
4.7 KiB
PL/PgSQL
-- Internal function.
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-- Set the seeds of the RNGs (Random Number Generators)
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-- used internally.
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CREATE OR REPLACE FUNCTION
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_cdb_random_seeds (seed_value INTEGER) RETURNS VOID
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AS $$
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from crankshaft import random_seeds
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random_seeds.set_random_seeds(seed_value)
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$$ LANGUAGE plpythonu;
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-- Moran's I
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CREATE OR REPLACE FUNCTION
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cdb_moran_local (
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t TEXT,
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attr TEXT,
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significance float DEFAULT 0.05,
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num_ngbrs INT DEFAULT 5,
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permutations INT DEFAULT 99,
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geom_column TEXT DEFAULT 'the_geom',
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id_col TEXT DEFAULT 'cartodb_id',
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w_type TEXT DEFAULT 'knn')
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RETURNS TABLE (moran FLOAT, quads TEXT, significance FLOAT, ids INT)
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AS $$
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from crankshaft.clustering import moran_local
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# TODO: use named parameters or a dictionary
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return moran_local(t, attr, significance, num_ngbrs, permutations, geom_column, id_col, w_type)
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$$ LANGUAGE plpythonu;
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-- Moran's I Local Rate
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CREATE OR REPLACE FUNCTION
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cdb_moran_local_rate(t TEXT,
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numerator TEXT,
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denominator TEXT,
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significance FLOAT DEFAULT 0.05,
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num_ngbrs INT DEFAULT 5,
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permutations INT DEFAULT 99,
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geom_column TEXT DEFAULT 'the_geom',
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id_col TEXT DEFAULT 'cartodb_id',
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w_type TEXT DEFAULT 'knn')
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RETURNS TABLE(moran FLOAT, quads TEXT, significance FLOAT, ids INT, y numeric)
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AS $$
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from crankshaft.clustering import moran_local_rate
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# TODO: use named parameters or a dictionary
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return moran_local_rate(t, numerator, denominator, significance, num_ngbrs, permutations, geom_column, id_col, w_type)
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$$ LANGUAGE plpythonu;
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-- Function by Stuart Lynn for a simple interpolation of a value
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-- from a polygon table over an arbitrary polygon
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-- (weighted by the area proportion overlapped)
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-- Aereal weighting is a very simple form of aereal interpolation.
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--
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-- Parameters:
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-- * geom a Polygon geometry which defines the area where a value will be
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-- estimated as the area-weighted sum of a given table/column
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-- * target_table_name table name of the table that provides the values
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-- * target_column column name of the column that provides the values
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-- * schema_name optional parameter to defina the schema the target table
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-- belongs to, which is necessary if its not in the search_path.
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-- Note that target_table_name should never include the schema in it.
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-- Return value:
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-- Aereal-weighted interpolation of the column values over the geometry
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CREATE OR REPLACE
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FUNCTION cdb_overlap_sum(geom geometry, target_table_name text, target_column text, schema_name text DEFAULT NULL)
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RETURNS numeric AS
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$$
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DECLARE
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result numeric;
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qualified_name text;
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BEGIN
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IF schema_name IS NULL THEN
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qualified_name := Format('%I', target_table_name);
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ELSE
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qualified_name := Format('%I.%s', schema_name, target_table_name);
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END IF;
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EXECUTE Format('
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SELECT sum(%I*ST_Area(St_Intersection($1, a.the_geom))/ST_Area(a.the_geom))
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FROM %s AS a
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WHERE $1 && a.the_geom
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', target_column, qualified_name)
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USING geom
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INTO result;
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RETURN result;
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END;
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$$ LANGUAGE plpgsql;
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--
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-- Creates N points randomly distributed arround the polygon
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--
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-- @param g - the geometry 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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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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$$
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LANGUAGE plpgsql VOLATILE
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