sql

2020-07-12 16:08:49 +00:00
parent f164cccbbf
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+Fill given extent with an hexagonal coverage
+
+#### Using the function
+
+Create a hexagonal grid from a polygon geometry. For example, take the geometry
+
+```sql
+  ST_SetSRID(
+    ST_Envelope(
+      ST_Collect(
+        ST_MakePoint(10000000,-10000000),
+        ST_MakePoint(-10000000,10000000)
+      )
+     ),
+     3857)
+```
+
+We can create a grid as follows, 
+
+```sql
+SELECT CDB_HexagonGrid(
+  ST_SetSRID(
+    ST_Envelope(
+      ST_Collect(
+        ST_MakePoint(10000000,-10000000),
+        ST_MakePoint(-10000000,10000000)
+      )
+     ),
+     3857),
+   1000000) the_geom_webmercator
+```
+
+Which will look something like this,
+
+![grid tile](http://i.imgur.com/4rZXGMb.png)
+
+#### Arguments
+
+CDB_HexagonGrid(ext, side, origin)
+
+* **ext** geometry. Extent to fill. Only hexagons with center point falling inside the extent (or at the lower or leftmost edge) will be emitted. The returned hexagons will have the same SRID as this extent.
+* **side** float. Side measure for the hexagon. Maximum diameter will be 2 * side. Measure is in the same projection as **ext**
+* **origin** OPTIONAL geometry. Optional origin to allow for exact tiling. If omitted the origin will be 0,0. The parameter is checked for having the same SRID as the extent.