## WellKnownGeometry.jl

Reading and writing Well Known Text (WKT) and Well Known Binary (WKB)
Author evetion
Popularity
3 Stars
Updated Last
8 Months Ago
Started In
April 2022

# WellKnownGeometry

Reading and writing Well Known Text (WKT) and Well Known Binary (WKB) based on GeoInterface.jl. See this Wikipedia page for an explanation of Well-known text and binary geometry.

Given a GeoInterface compatible geometry, this package can generate the WKT and WKB representation of it. It also does the reverse, as it implements GeoInterface for WKT or WKB strings.

## WellKnownText

Given a WKT string, we can retrieve the type and underlying coordinates, and thus convert it to other geometries using GeoInterface. Note that WKT strings are wrapped by GeoFormatTypes so we can distinguish them from any other strings.

```using ArchGDAL
using GeoFormatTypes
using WellKnownGeometry
using GeoInterface

wkts = "POINT (30 10)"
wkt = GeoFormatTypes.WellKnownText(GeoFormatTypes.Geom(), wkts)

GeoInterface.geomtrait(wkt)  # PointTrait()
GeoInterface.ncoord(wkt)  # 2
GeoInterface.coordinates(wkt)  # 2-element Vector{Float64}: 30.0 10.0

p = convert(ArchGDAL.IGeometry{ArchGDAL.wkbPoint}, wkt)  # Geometry: POINT (30 10)```

As ArchGDAL geometries implement GeoInterface, we can generate the WKT for it.

```wkt = WellKnownGeometry.getwkt(p)  # WellKnownText{GeoFormatTypes.Geom}(GeoFormatTypes.Geom(), "POINT (30.0 10.0)")
GeoFormatTypes.val(wkt)  # "POINT (30.0 10.0)"```
``````getwkt
``````

## WellKnownBinary

Given a WKB byte string, we can retrieve the type and underlying coordinates, and thus convert it to other geometries using GeoInterface. Note that WKB byte strings are wrapped by GeoFormatTypes so we can distinguish them from any other byte strings.

```using ArchGDAL
using GeoFormatTypes
using WellKnownGeometry
using GeoInterface

wkbs = [0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x3e, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x24, 0x40]
wkb = GeoFormatTypes.WellKnownBinary(GeoFormatTypes.Geom(), wkbs)

GeoInterface.geomtrait(wkb)  # PointTrait()
GeoInterface.ncoord(wkb)  # 2
GeoInterface.coordinates(wkb)  # 2-element Vector{Float64}: 30.0 10.0

p = convert(ArchGDAL.IGeometry{ArchGDAL.wkbPoint}, wkb)  # Geometry: POINT (30 10)```

As ArchGDAL geometries implement GeoInterface, we can generate the WKB for it.

```wkb = WellKnownGeometry.getwkb(p)  # WellKnownBinary{GeoFormatTypes.Geom, Vector{UInt8}}(GeoFormatTypes.Geom(), UInt8[0x01, ..., 0x40])
GeoFormatTypes.val(wkb)  # 21-element Vector{UInt8}:  0x01 0x01 ... 0x00 0x40```
``````getwkb
``````