Well-known text (WKT)
Well-Known Text (WKT) is an ASCII representation of a spatial object.
Well-Known Text (WKT) is an ASCII representation of a spatial object.
WKTs are not case sensitive; Vertica recognizes any combination of lowercase and uppercase letters.
Some examples of valid WKTs are:
| WKT Example | Description |
|---|---|
| POINT(1 2) | The point (1,2) |
| MULTIPOINT(0 0,1 1) | A set made up of the points (0,0) and (1,1) |
| LINESTRING(1.5 2.45,3.21 4) | The line from the point (1.5,2.45) to the point (3.21,4) |
| MULTILINESTRING((0 0,–1 –2,–3 –4),(2 3,3 4,6 7)) | Two linestrings, one that passes through (0,0), (–1,–2), and (–3,–4), and one that passes through (2,3), (3,4), and (6,7). |
| POLYGON((1 2,1 4,3 4,3 2,1 2)) | The rectangle whose four corners are indicated by (1,2), (1,4), (3,4), and (3,2). A polygon must be closed, so the first and last points in the WKT must match. |
| POLYGON((0.5 0.5,5 0,5 5,0 5,0.5 0.5), (1.5 1,4 3,4 1,1.5 1)) | A polygon (0.5 0.5,5 0,5 5,0 5,0.5 0.5) with a hole in it (1.5 1,4 3,4 1,1.5 1). |
| MULTIPOLYGON(((0 1,3 0,4 3,0 4,0 1)), ((3 4,6 3,5 5,3 4)), ((0 0,–1 –2,–3 –2,–2 –1,0 0))) | A set of three polygons |
| GEOMETRYCOLLECTION(POINT(5 8), LINESTRING(–1 3,1 4)) | A set containing the point (5,8) and the line from (–1,3) to (1,4) |
|
POINT EMPTY MULTIPOINT EMPTY LINESTRING EMPTY MULTILINESTRING EMPTY MULTILINESTRING(EMPTY) POLYGON EMPTY POLYGON(EMPTY) MULTIPOLYGON EMPTY MULTIPOLYGON(EMPTY) |
Empty spatial objects; empty objects have no points. |
Invalid WKTs are:
-
POINT(1 NAN), POINT(1 INF)—Coordinates must be numbers.
-
POLYGON((1 2, 1 4, 3 4, 3 2))—A polygon must be closed.
-
POLYGON((1 4, 2 4))—A linestring is not a valid polygon.