Changes between Version 2 and Version 3 of UsersWikiCreateFishnet

Timestamp:

06/16/13 21:25:18 (11 years ago)

Author:

Mike Taves

Comment:

make a set-returning function instead

UsersWikiCreateFishnet

@@ -3 +3 @@
 Make a 2D grid of rectangular polygons, which is sometimes called a fishnet grid.
 
-Use the following source:
+Use the following source for a set returning function:
 {{{
 CREATE OR REPLACE FUNCTION ST_CreateFishnet(
         nrow integer, ncol integer,
         xsize float8, ysize float8,
-        x0 float8 DEFAULT 0, y0 float8 DEFAULT 0)
-    RETURNS SETOF geometry AS
+        x0 float8 DEFAULT 0, y0 float8 DEFAULT 0,
+        OUT "row" integer, OUT col integer,
+        OUT geom geometry)
+    RETURNS SETOF record AS
 $$
-SELECT ST_Translate(cell, j * $3 + $5, i * $4 + $6)
+SELECT i + 1 AS row, j + 1 AS col, ST_Translate(cell, j * $3 + $5, i * $4 + $6) AS geom
 FROM generate_series(0, $1 - 1) AS i,
      generate_series(0, $2 - 1) AS j,
@@ -19 +21 @@
 $$ LANGUAGE sql IMMUTABLE STRICT;
 }}}
-Where:
+Where input parameters:
  {{{nrow}}} integer::
   number of rows in ''y''-direction
@@ -33 +35 @@
   origin offset in ''y''-direction; DEFAULT is 0
 
+Returning output parameters are:
+ {{{row}}} integer::
+  row number, starting from 1 at the bottom
+ {{{col}}} integer::
+  column number, starting from 1 at the left
+ {{{geom}}} geometry::
+  grid cell geometry
+
 Example:
 {{{
-SELECT ST_Collect(cells)
-FROM ST_CreateFishnet(4,6,10,10) AS cells;
+SELECT ST_Collect(cells.geom)
+FROM ST_CreateFishnet(4, 6, 10, 10) AS cells;
 }}}
 [[Image(http://i.stack.imgur.com/vQY0Z.png)]]