I'm trying to implement this function to create a hex grid over a layer.
However, when I implement it and export it via pgsql2shp the results ends up empty. The query I used is below
CREATE TABLE hex_grid (gid serial not null primary key); SELECT addgeometrycolumn('hex_grid','the_geom', 0, 'POLYGON', 2); CREATE OR REPLACE FUNCTION genhexagons(width float, xmin float,ymin float,xmax float,ymax float ) RETURNS float AS $total$ declare b float :=width/2; a float :=b/2; --sin(30)=.5 c float :=2*a; height float := 2*a+c; --1.1547*width; ncol float :=ceil(abs(xmax-xmin)/width); nrow float :=ceil(abs(ymax-ymin)/height); polygon_string varchar := 'POLYGON((' || 0 || ' ' || 0 || ' , ' || b || ' ' || a || ' , ' || b || ' ' || a+c || ' , ' || 0 || ' ' || a+c+a || ' , ' || -1*b || ' ' || a+c || ' , ' || -1*b || ' ' || a || ' , ' || 0 || ' ' || 0 || '))'; BEGIN INSERT INTO hex_grid (the_geom) SELECT st_translate(the_geom, x_series*(2*a+c)+xmin, y_series*(2*(c+a))+ymin) from generate_series(0, ncol::int , 1) as x_series, generate_series(0, nrow::int,1 ) as y_series, ( SELECT polygon_string::geometry as the_geom UNION SELECT ST_Translate(polygon_string::geometry, b , a+c) as the_geom ) as two_hex; ALTER TABLE hex_grid ALTER COLUMN the_geom TYPE geometry(Polygon, 4326) USING ST_SetSRID(the_geom,4326); RETURN NULL; END; $total$ LANGUAGE plpgsql; --width in the units of the projection, xmin,ymin,xmax,ymax SELECT genhexagons(1.0, -124.8, 25.10, -66.9, 49.6); And then I export it using the pgsql2shp pgsql2shp -f test -h wideload -u minhmai -P 0ptimuspassword! test_nd_2016g "select * from hex_grid"
But when I open it in QGIS, the shapefile is blank. I'm not sure about what the function really does but I assume it should have something when exported, especially since the output indicated that there are rows.
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However, when I implement it and export it via pgsql2shp the results ends up empty. The query I used is below
CREATE TABLE hex_grid (gid serial not null primary key); SELECT addgeometrycolumn('hex_grid','the_geom', 0, 'POLYGON', 2); CREATE OR REPLACE FUNCTION genhexagons(width float, xmin float,ymin float,xmax float,ymax float ) RETURNS float AS $total$ declare b float :=width/2; a float :=b/2; --sin(30)=.5 c float :=2*a; height float := 2*a+c; --1.1547*width; ncol float :=ceil(abs(xmax-xmin)/width); nrow float :=ceil(abs(ymax-ymin)/height); polygon_string varchar := 'POLYGON((' || 0 || ' ' || 0 || ' , ' || b || ' ' || a || ' , ' || b || ' ' || a+c || ' , ' || 0 || ' ' || a+c+a || ' , ' || -1*b || ' ' || a+c || ' , ' || -1*b || ' ' || a || ' , ' || 0 || ' ' || 0 || '))'; BEGIN INSERT INTO hex_grid (the_geom) SELECT st_translate(the_geom, x_series*(2*a+c)+xmin, y_series*(2*(c+a))+ymin) from generate_series(0, ncol::int , 1) as x_series, generate_series(0, nrow::int,1 ) as y_series, ( SELECT polygon_string::geometry as the_geom UNION SELECT ST_Translate(polygon_string::geometry, b , a+c) as the_geom ) as two_hex; ALTER TABLE hex_grid ALTER COLUMN the_geom TYPE geometry(Polygon, 4326) USING ST_SetSRID(the_geom,4326); RETURN NULL; END; $total$ LANGUAGE plpgsql; --width in the units of the projection, xmin,ymin,xmax,ymax SELECT genhexagons(1.0, -124.8, 25.10, -66.9, 49.6); And then I export it using the pgsql2shp pgsql2shp -f test -h wideload -u minhmai -P 0ptimuspassword! test_nd_2016g "select * from hex_grid"
But when I open it in QGIS, the shapefile is blank. I'm not sure about what the function really does but I assume it should have something when exported, especially since the output indicated that there are rows.
أكثر...