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Explain behaviour for various geometric types and array shapes

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Blargian 2024-03-16 13:18:56 +01:00
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docs/en/sql-reference/functions/geo/polygon.md
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@ -6,7 +6,11 @@ title: "Functions for Working with Polygons"
## WKT
Returns a WKT (Well Known Text) geometric object from tuples which represent point coordinates.
Returns a WKT (Well Known Text) geometric object from tuples which represent point coordinates. Supported WKT objects are:
- POINT
- POLYGON
- MULTIPOLYGON
**Syntax**
@ -20,16 +24,40 @@ WKT(points)
**Returned value**
WKT (Well Known Text) geometric object.
- POINT is returned for a tuple.
- POLYGON is returned for an array of tuples.
- MULTIPOLYGON is returned for an array of tuple arrays.
**Example**
**Examples**
POINT from tuple:
```sql
SELECT wkt([[(0., 0.), (10., 0.), (10., 10.), (0., 10.)], [(4., 4.), (5., 4.), (5., 5.), (4., 5.)]]);
SELECT wkt((0., 0.));
```
```response
POLYGON((0 0,10 0,10 10,0 10,0 0),(4 4,5 4,5 5,4 5,4 4))
POINT(0 0)
```
POLYGON from an array of tuples:
```sql
SELECT wkt([(0., 0.), (10., 0.), (10., 10.), (0., 10.)]);
```
```response
POLYGON((0 0,10 0,10 10,0 10))
```
MULTIPOLYGON from an array of multi-dimensional tuple arrays:
```sql
SELECT wkt([[[(0., 0.), (10., 0.), (10., 10.), (0., 10.)], [(4., 4.), (5., 4.), (5., 5.), (4., 5.)]], [[(-10., -10.), (-10., -9.), (-9., 10.)]]]);
```
```response
MULTIPOLYGON(((0 0,10 0,10 10,0 10,0 0),(4 4,5 4,5 5,4 5,4 4)),((-10 -10,-10 -9,-9 10,-10 -10)))
```
## readWKTMultiPolygon